"dennis@home" wrote in message
eb.com...
Its the same as a film camera, where do you think it
differs? Why do you even think it might differ?

My thoughts exactly. I can't work out whether he really doesn't
know or is winding us all up. Film and digital cameras have
more in common that maybe he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you. We are also talking
about qwhich is best for teaching photography. Teaching photography
adn gettiogn a good picture aren't the same.

There are no differences, if you can't list them i will continue to
state there are no differences. Its up to you to state what you think
they are or stop saying there are differences.

Is whisky dave for real? He makes sweeping statements but adopts the
coward's way out "if you don't know I can't be bothered to tell you". It
doesn't really matter whether he's right in his assertions or is just
evading the issue - he's evidently nothing further to contribute to the
argument. Case dismissed because of lack of evidence!

In message , NY
writes
"dennis@home" wrote in message
web.com...
Its the same as a film camera, where do you think it
differs? Why do you even think it might differ?

My thoughts exactly. I can't work out whether he really doesn't
know or is winding us all up. Film and digital cameras have
more in common that maybe he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you. We are also talking
about qwhich is best for teaching photography. Teaching photography
adn gettiogn a good picture aren't the same.

There are no differences, if you can't list them i will continue to
state there are no differences. Its up to you to state what you think
they are or stop saying there are differences.

Is whisky dave for real? He makes sweeping statements but adopts the
coward's way out "if you don't know I can't be bothered to tell you".
It doesn't really matter whether he's right in his assertions or is
just evading the issue - he's evidently nothing further to contribute
to the argument. Case dismissed because of lack of evidence!

He seems to like these endless arguments. I try not get involved in them
anymore
--
Chris French

On Tuesday, 29 September 2015 13:43:26 UTC+1, NY wrote:
"dennis@home" wrote in message
eb.com...
Its the same as a film camera, where do you think it
differs? Why do you even think it might differ?

My thoughts exactly. I can't work out whether he really doesn't
know or is winding us all up. Film and digital cameras have
more in common that maybe he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you. We are also talking
about qwhich is best for teaching photography. Teaching photography
adn gettiogn a good picture aren't the same.

There are no differences, if you can't list them i will continue to
state there are no differences. Its up to you to state what you think
they are or stop saying there are differences.

Is whisky dave for real? He makes sweeping statements but adopts the
coward's way out "if you don't know I can't be bothered to tell you". It
doesn't really matter whether he's right in his assertions or is just
evading the issue - he's evidently nothing further to contribute to the
argument. Case dismissed because of lack of evidence!

I've shown the evidence you've ignored it.

On Tuesday, 29 September 2015 13:37:38 UTC+1, whisky-dave wrote:

No it doesn't as few even notice. A friend of mine spent quite a time in a musuem takign videos all with a yellow orange cast he thought there's was something wrong with his camera, of course he didn;t realise this until he got home.
Me I knew immediatly what the problem was because I know about film and digital and the differencies between them. I'd have set the white balance before I started recording. He thought the scene looked OK no colour cast and digital cameras arn;t effected by such things as colour temerature of teh light source.
THIS IS A DIFFERENCE.

Film & digital are affected much the same by colour balance, but digitals then correct it, for some hit & miss & limited value of corrected. The end result problems that crop up are much the same, except that film is passive, and thus reflects consistently any difference between film colour balance and lighting/scene colour balance, whereas digital produces much more varied results when in automated colour balance mode.


NT

On 29/09/2015 12:27, whisky-dave wrote:
On Monday, 28 September 2015 18:48:46 UTC+1, dennis@home wrote:
On 28/09/2015 17:03, whisky-dave wrote:



Do the optics of lenses behave differently?

No that I know of.

They behave differently as film has a different response to off
axis images than a digital sensor does.

As far as I know the light traveling through lenes behaves the same
irrespective of whether the camera has a film or sensor in it.

I didn't mention the lens.

Does the reciprocity law (halve shutter speed so double
aperture etc) behave differently?

Yes significantly.

they are the same.

wrong.

How do they differ



It only matters in extreme cases.

so they aren't the same then are they.

They are for 99.999999999999999999999999999999999999% of pictures.
If you are taking those 0.0000000000000000000000000000000000001% you
will know how to do it and be using digital anyway.

you need to correct the exposure using characteristics that
change from one make of film to another;

yuo don;t get that with digital, you don't even have to think
about it.

You can change how the sensor responds and what is recorded so you
do need to think about it.

yuo can't change how a sensor responds. It is an electronic device
which has charastretics which the user can NOT change.

Of course you can, bining, iso, etc.

So when studying photogrphy like my friend was who won a pjhopt
comp in spain. She works at a uni teaching photography and is an
adobe registered certified to teach.

???

teaching photography is differnt to getting someone to take the same
snapshot as you can.

Yes its understanding how to compose and use your equipment.
It isn't restricted to old fashioned film.
You can teach it on a phone if its the right phone.


You might be making life more difficult for him if you make
him avoid using P or Av/Tv mode, but it will make it easier to
learn initially.

They have to know what those terms mean and why you use them.

That is what you are teaching isn't it?

Yes, and you DON'T even need a camera to teach that.


You give a kid a digital camera that is **** compared to their
mobile phone they get board unintrested and disruptive. Now you
have 20 kids around you not concentrating they'd rather use their
phone to get a far better picture than they could ever get with
the digital camera you've supplied.

So what are you trying to teach them if its not how to get a
better picture, it sounds like you have given them cr@p and expect
them to use it. I take it your film camera of choice is a box
brownie.

No, but you wouldn't give them a smart phone, even though most
people could get better pictures with it.

A smart phone could well be a good choice, if it has manual controls.
You could write an app and do online teaching.

Why does the image on my LCD look the same irrespected
of the aperature and shutter speed I set.

Because you have a cr@p camera

wrong answer .

So what's your answer? Is it that the image on an LCD screen
(either when used as a viewfinder or when examining the
pictures after taking) is too small to be able to distinguish
clearly between in-focus and out-of focus parts of the scene?

No because when you look at the screen you see what you might end
up with.

That is what you use a viewfinder for to see what you may get.

exactly what you may get.

No film camera shows exactly what you get, they don't do 100% views to
start with.



you are going to take a p[icture of usain bolt in teh 100 meters
on the left is the start on the right is the finish. Are yuo
saying they'll be no differnce whether the exposure is 1/1000 or
1 second. the aperature will take care of itself, but will what
you see on the screen be the same as the images yuo take. NO.

That is true of the viewfinder on your camera and is no different
to a digital camera., especially an SLR.

No it's not. A LCD well most DLSR or digital camera LCDs change
brightness depending on your setting or AP and Tv so you can still
see teh display and the brightness of teh dispalay will change
depending on you;'r settings. This is NOT true of a film SLR.

Of course it is true of all digital SLRs, they have the same optics as
film SLRs. The display is an extra that you can use on some digitals as
not all have live view.



So far you haven't pointed out any difference between learning on
a digital and a film camera other than the ability to view the
results.

So far you have proved you know noting about teaching.


I am pretty sure you are barking up the wrong tree teaching using film.
You should teach the basics using a digital camera and then explain the
differences with film if anyone actually wants to use it.

On Tuesday, 29 September 2015 13:43:26 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
f number is a measure of aperture *diameter* relative to lens focal
length.



Its the same as a film camera, where do you think it differs?
Why do you even think it might differ?

My thoughts exactly. I can't work out whether he really doesn't know
or is
winding us all up. Film and digital cameras have more in common that
maybe
he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you.
We are also talking about qwhich is best for teaching photography.
Teaching photography adn gettiogn a good picture aren't the same.

Sorry. Anyone who says "you are wrong but I can't be bothered to explain
why" has just proved that they are not worth listening to.

anyone that can;t tell teh differncies or even a single differnce between a digital camera and a film one is'nt worth talking to are they.
If they have a camera in their hand how will they know whether it's digital or film if they don;t know the differnce ?


You may have a very good point to make - there may be differences .

well I listed some in my 2nd post 1st wouldn't post came back with some error.

in the way
that you use aperture and shutter speed between film and digital, but I
can't think of any and neither can dennis@home.

that's NOT my problem.



You've implied that a camera with manual settings (and maybe even with no
automatic settings) is needed to teach photography.

If you use words I haven;t used .....

I NEVER said, plese only quote what I have said.
I DID NOT say a film camera is NEEDED to teach photography.

I said it's better for teaching PHOTOGRAPHY.
and please NOTE that for me photography and selfies and the average baby snap is NOT the same for me.


To some extent I agree
with you - about the former, if not the latter. Where you would find such a
camera out of current models of film and digital camera is the problem.

Someone would have to think carefully about which product wpould be best for teaching photgraphy. I would NOT advise an iphone6 even teh s+ version.


But you've not made a convincing case for saying that a film camera is
better than a digital camera for learning the principles of photography,

for that I would need to be convinced that those that I was discussing it with had a clue about photography otherwise it's be like talking about women with Rod speed as he can't tell the differnce between a womens arse and a sheeps
as long as they're called shiela ;-)

because every time you've been challenged to elaborate your sweeping
statements, you've ducked the issue.

No as you have done you change what I say then expect me to defned what you've said.
Show me again where I have said you need a film camera to teach photography .

On 29/09/2015 13:37, whisky-dave wrote:
On Tuesday, 29 September 2015 12:22:48 UTC+1, dennis@home wrote:
On 29/09/2015 12:05, whisky-dave wrote:


My thoughts exactly. I can't work out whether he really
doesn't know or is winding us all up. Film and digital
cameras have more in common that maybe he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you. We are also
talking about qwhich is best for teaching photography. Teaching
photography adn gettiogn a good picture aren't the same.

There are no differences,

I can tell the differnce you can't.


No I've vere said that. are you sugeswstin we don;t need a light
meter because we have a digital camera ?.

Well its obvious that you can get the exposure by trial and error.

with a DIGITAL cameras can be acheived by just loking at the LCD. Now
tell me how you can do this with a film camera looking through the
viewfinder.

THIS IS A DIFFERENCE


this can be achived and that you can do that trial and error there
and then with a decent digital camera. you will claim that that's
too easy which i will ignore.

Of course you'll ignore it, because it proves you're wrong. Try
adjusing the aperature and the exposure time on a SLR film camera and
see if teh viwfinder image changes in any way. THIS IS A DIFFERENCE

You can select the 'speed' aka ISO of the 'sensor' either increase it
or decrease it for any frame or picture.

Now coem on tell me how you do this with film in the camera what
button do you use to increase/decrease the films speed. THIS IS A
DIFFERENCE .

With a DIGITAL camera you can increase/decrease Ap Tv and ISO. With a
film camera you CAN NOT change the ISO unless you change film or
change the way you process it AFTER taking the picture. THIS IS A
DIFFERENCE

which means with film you have to THINK before you even put the film
in the camera, you don;t have the same thoughts choosing a memory
card do you. THIS IS A DIFFERENCE

With film you have to decide whether or not you're taking colour or
monochrome, or transparancies, although colour film can be converted
to monochrome it's a bit wasteful. No sucvh thing with digital
cameras is theres. THIS IS A DIFFERENCE







cause the f..king sun goes in or it gets dark or night
approaches. you know brightness changes throught they day. Your
LCD and eyes react to changing light levels differntly and to
colur differntly.

Your eyes do, the camera doesn't.

yes it does compared to your eyes. have you never heard of tungsten
film ? THIS IS A DIFFERENCE


can yuo tell me what AWB is and what other options there are on a
typical digital camera can you show me these option for film ? THIS
IS A DIFFERENCE


You can see what the changes mean on a digital camera after you
take a picture you can only guess with film until you have it
processed.

THIS IS A DIFFERENCE

Having such a long delay doesn't aid teaching so digital is best
there too.

No it doesn't as few even notice. A friend of mine spent quite a time
in a musuem takign videos all with a yellow orange cast he thought
there's was something wrong with his camera, of course he didn;t
realise this until he got home. Me I knew immediatly what the problem
was because I know about film and digital and the differencies
between them. I'd have set the white balance before I started
recording. He thought the scene looked OK no colour cast and digital
cameras arn;t effected by such things as colour temerature of teh
light source. THIS IS A DIFFERENCE.


Its not a difference as far as teaching photography.
You obviously need a special camera tailored to your idea of what to teach.

the same as on a film camera or are you proposing that only
manual lenses are allowed.

if you want to learn about lenses use a manual lens, just like
you would a car.

A manual lens and an auto iris lens produce the same images.

my lenes from my film cameras have aprature rings I can turn to stop
down the lens. They also have a DOF scale and an IR mark, even a
distance scale on some.

So do mine on my digital.

Only preview and metering differ and they differ the same for film
and digital.

I've never seen image stablisation on a lens designed for film
cameras.

One of the reasons why digitals work better.
You can turn it off on all of them.

See as far as teaching goes there are no differences between film and
digital unless you decide to use them.

On Tuesday, 29 September 2015 15:06:41 UTC+1, dennis@home wrote:
On 29/09/2015 13:37, whisky-dave wrote:
On Tuesday, 29 September 2015 12:22:48 UTC+1, dennis@home wrote:
On 29/09/2015 12:05, whisky-dave wrote:


My thoughts exactly. I can't work out whether he really
doesn't know or is winding us all up. Film and digital
cameras have more in common that maybe he realises.

They sure do, but there are some important differncies.

You still haven't said what they are, I don't think you know.

if you don't know I'm not listing them for you. We are also
talking about qwhich is best for teaching photography. Teaching
photography adn gettiogn a good picture aren't the same.

There are no differences,

I can tell the differnce you can't.


No I've vere said that. are you sugeswstin we don;t need a light
meter because we have a digital camera ?.

Well its obvious that you can get the exposure by trial and error.

with a DIGITAL cameras can be acheived by just loking at the LCD. Now
tell me how you can do this with a film camera looking through the
viewfinder.

THIS IS A DIFFERENCE


this can be achived and that you can do that trial and error there
and then with a decent digital camera. you will claim that that's
too easy which i will ignore.

Of course you'll ignore it, because it proves you're wrong. Try
adjusing the aperature and the exposure time on a SLR film camera and
see if teh viwfinder image changes in any way. THIS IS A DIFFERENCE

You can select the 'speed' aka ISO of the 'sensor' either increase it
or decrease it for any frame or picture.

Now coem on tell me how you do this with film in the camera what
button do you use to increase/decrease the films speed. THIS IS A
DIFFERENCE .

With a DIGITAL camera you can increase/decrease Ap Tv and ISO. With a
film camera you CAN NOT change the ISO unless you change film or
change the way you process it AFTER taking the picture. THIS IS A
DIFFERENCE

which means with film you have to THINK before you even put the film
in the camera, you don;t have the same thoughts choosing a memory
card do you. THIS IS A DIFFERENCE

With film you have to decide whether or not you're taking colour or
monochrome, or transparancies, although colour film can be converted
to monochrome it's a bit wasteful. No sucvh thing with digital
cameras is theres. THIS IS A DIFFERENCE







cause the f..king sun goes in or it gets dark or night
approaches. you know brightness changes throught they day. Your
LCD and eyes react to changing light levels differntly and to
colur differntly.

Your eyes do, the camera doesn't.

yes it does compared to your eyes. have you never heard of tungsten
film ? THIS IS A DIFFERENCE


can yuo tell me what AWB is and what other options there are on a
typical digital camera can you show me these option for film ? THIS
IS A DIFFERENCE


You can see what the changes mean on a digital camera after you
take a picture you can only guess with film until you have it
processed.

THIS IS A DIFFERENCE

Having such a long delay doesn't aid teaching so digital is best
there too.

No it doesn't as few even notice. A friend of mine spent quite a time
in a musuem takign videos all with a yellow orange cast he thought
there's was something wrong with his camera, of course he didn;t
realise this until he got home. Me I knew immediatly what the problem
was because I know about film and digital and the differencies
between them. I'd have set the white balance before I started
recording. He thought the scene looked OK no colour cast and digital
cameras arn;t effected by such things as colour temerature of teh
light source. THIS IS A DIFFERENCE.


Its not a difference as far as teaching photography.

Yes it is, with digital it's easy to change it after taking the photo or retake the shot or even in post processing. Not quite so easy with film.
WHich means with film if you're going to take pictures under anyhting other than daylight you need to think about it, even before loading the camera.
Have you ever had to think about teh shots you are going to take before taking them in this way ?
How many times has the decision of which media to choose has been dictated by whether you're shooting in daylight artificail or even at night. ?




You obviously need a special camera tailored to your idea of what to teach.

No just one where you can alter Av Tv focus, compensation, ISO, all idependantly.



the same as on a film camera or are you proposing that only
manual lenses are allowed.

if you want to learn about lenses use a manual lens, just like
you would a car.

A manual lens and an auto iris lens produce the same images.

my lenes from my film cameras have aprature rings I can turn to stop
down the lens. They also have a DOF scale and an IR mark, even a
distance scale on some.


In fact I have 2 DoF marks on my film camera.
But I bet you don't know what they are for.

So do mine on my digital.


which one is that then. ?




Only preview and metering differ and they differ the same for film
and digital.

I've never seen image stablisation on a lens designed for film
cameras.

One of the reasons why digitals work better.
You can turn it off on all of them.

doesn't mean the lens works any better. What it can do is help eliminate camera shake.
Which is why you don;t know about teaching photography.
A lens with IS will help you get a picture with less camera shake,
it CAN NOT ensure you get a good picture that is down to the photographer in what's he's framed and his knowledge of the subject will depend on what shot he gets.




See as far as teaching goes there are no differences between film and
digital unless you decide to use them.

So I'm right there sis a differnce even more significant when you
teach the subject.

On 29/09/2015 16:04, whisky-dave wrote:

8

Its not a difference as far as teaching photography.

Yes it is, with digital it's easy to change it after taking the photo
or retake the shot or even in post processing. Not quite so easy with
film. WHich means with film if you're going to take pictures under
anyhting other than daylight you need to think about it, even before
loading the camera. Have you ever had to think about teh shots you
are going to take before taking them in this way ? How many times has
the decision of which media to choose has been dictated by whether
you're shooting in daylight artificail or even at night. ?

So its only photography if its difficult to do.
Best of luck teaching that.

You obviously need a special camera tailored to your idea of what
to teach.

No just one where you can alter Av Tv focus, compensation, ISO, all
idependantly.

Like you can on many digitals.

the same as on a film camera or are you proposing that
only manual lenses are allowed.

if you want to learn about lenses use a manual lens, just
like you would a car.

A manual lens and an auto iris lens produce the same images.

my lenes from my film cameras have aprature rings I can turn to
stop down the lens. They also have a DOF scale and an IR mark,
even a distance scale on some.


In fact I have 2 DoF marks on my film camera. But I bet you don't
know what they are for.

So do mine on my digital.


which one is that then. ?

Which one what?
they are on the lenses not the camera.
and they have IR focusing marks too.




Only preview and metering differ and they differ the same for
film and digital.

I've never seen image stablisation on a lens designed for film
cameras.

One of the reasons why digitals work better. You can turn it off on
all of them.

doesn't mean the lens works any better. What it can do is help
eliminate camera shake. Which is why you don;t know about teaching
photography. A lens with IS will help you get a picture with less
camera shake, it CAN NOT ensure you get a good picture that is down
to the photographer in what's he's framed and his knowledge of the
subject will depend on what shot he gets.

Which is why a digital camera is just as good if not better than a film
camera.
Now you have finally got there I think we can stop this thread.


See as far as teaching goes there are no differences between film
and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when you
teach the subject.

Rubbish.



BTW I know more about photography than you do as you obviously can't
tell us the difference between digital cameras and film cameras.


Bye.

On Tuesday, 29 September 2015 21:03:59 UTC+1, dennis@home wrote:
On 29/09/2015 16:04, whisky-dave wrote:

8

Its not a difference as far as teaching photography.

Yes it is, with digital it's easy to change it after taking the photo
or retake the shot or even in post processing. Not quite so easy with
film. WHich means with film if you're going to take pictures under
anyhting other than daylight you need to think about it, even before
loading the camera. Have you ever had to think about teh shots you
are going to take before taking them in this way ? How many times has
the decision of which media to choose has been dictated by whether
you're shooting in daylight artificail or even at night. ?

So its only photography if its difficult to do.
Best of luck teaching that.

It's skill not luck and yes it's about teaching PHOTOGRAPHY
and NOT how to take a snap.
Just because you can't tell, the differnce it doesbn't mean there isn't one.




You obviously need a special camera tailored to your idea of what
to teach.

No just one where you can alter Av Tv focus, compensation, ISO, all
idependantly.

Like you can on many digitals.

Yes,but tehre are so many varibles and setting, and as you
differnt know the differnices between digital and film then expecting you to teach it would be a waste of time, which is probbaly why you don't teach anything. No suprise there.


In fact I have 2 DoF marks on my film camera. But I bet you don't
know what they are for.

So do mine on my digital.


which one is that then. ?

you can't even work that out !

what does the sentance "So do mine on my digital"

Are you refering to the DoF marks tatooed on your penis.

your digital what.....






Which one what?
they are on the lenses not the camera.
and they have IR focusing marks too.

I have a DoF mark on my camera.
You don't even know what that is do you, or what it's for.

So what digital cameras and lenses do you own or have even used.
Lets face it you think digital and film cameras are the same, or yuo didn;t know there's was a differnce.


Which is why a digital camera is just as good if not better than a film
camera.

but NOT for teaching which is the point.
but of course if yuo know so litle about teaching you probably think a mobile phone is even better for teaching everythijng because it's digital can take phones has a spell checker and can play music better than a record player can.

Now you have finally got there I think we can stop this thread.


See as far as teaching goes there are no differences between film
and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when you
teach the subject.

Rubbish.

Fact, which is something you haven't understood.




BTW I know more about photography than you do as you obviously can't
tell us the difference between digital cameras and film cameras.

already have done bye ****wit.

"whisky-dave" wrote in message
...
In fact I have 2 DoF marks on my film camera. But I bet you don't
know what they are for.

So do mine on my digital.


which one is that then. ?

you can't even work that out !

what does the sentance "So do mine on my digital"

Are you refering to the DoF marks tatooed on your penis.

your digital what.....

Since someone (I think it was you but I'm not certain of the quoting) said
"I have two DoF marks on my film camera" and someone else replied to that
with "So do mine on my digital" I presume the latter was referring to a
digital *camera* since a camera is what you referred to previously. Standard
rules of English that you don't always need to repeat the noun..

I presume both of you are slightly imprecise since the marks will be on the
lenses for the film or digital camera rather than on the camera bodies
themselves.

As to the two marks, my first thought is visible and infra-red, unless they
are for the two extremes of a zoom lens (narrower DoF for same aperture at
longer focal length). For visible/IR, I presume as well as two DoF marks
there are two focus marks and that the different pairs of DoF marks are
roughly equally spaced about the respective focus mark.

Have I understood your question correctly? Are the two sets of DoF marks
(and also the marks for the different focus points) in different colours?
That's usually the convention for visible/IR.

On Wednesday, 30 September 2015 16:32:49 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
In fact I have 2 DoF marks on my film camera. But I bet you don't
know what they are for.

So do mine on my digital.


which one is that then. ?

you can't even work that out !

what does the sentance "So do mine on my digital"

Are you refering to the DoF marks tatooed on your penis.

your digital what.....

Since someone (I think it was you but I'm not certain of the quoting) said
"I have two DoF marks on my film camera"

that was me although I said I have two DoF ones on teh lens the other on the camera.

and someone else replied to that
with "So do mine on my digital" I presume the latter was referring to a
digital *camera* since a camera is what you referred to previously. Standard
rules of English that you don't always need to repeat the noun..

I agree so I'm awaiting to find out on which digital camera this or those DoF marks appear.


I presume both of you are slightly imprecise since the marks will be on the
lenses for the film or digital camera rather than on the camera bodies
themselves.

Wrong.
mine is ON THE CAMERA but to understand this with film you have to know what the mark represents.


As to the two marks, my first thought is visible and infra-red, unless they
are for the two extremes of a zoom lens (narrower DoF for same aperture at
longer focal length). For visible/IR, I presume as well as two DoF marks
there are two focus marks and that the different pairs of DoF marks are
roughly equally spaced about the respective focus mark.

No.


Have I understood your question correctly? Are the two sets of DoF marks
(and also the marks for the different focus points) in different colours?
That's usually the convention for visible/IR.

I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.

"whisky-dave" wrote in message
...
I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the
london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film
will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.

Ah! I didn't appreciate that your use of "DoF" wasn't referring to depth of
field, as I think a lot of other people had been using that abbreviation
earlier in the thread, but instead referred to depth of focus, more commonly
called focal plane. I wonder how many other people made the same
misunderstanding of what you were saying. If you'd mentioned the crucial
detail about "London Underground sign" I'd have known what you meant and
realised that you really *did* mean on the camera rather than on the lens.

Now I wonder why you have *two* of those marks. Given that the plane of both
visible and IR film will be the same, it's nothing to do with that. What
could the second mark relate to? I'm even more puzzled because in
http://www.mir.com.my/rb/photography...topviewblk.jpg I
can only see one mark.


By the way, digital cameras have the same mark as well, marking the
equivalent place: the location of the sensor as opposed to the film - eg
http://imaging.nikon.com/lineup/dslr/basics/19/04.htm which relates to
DSLRs.

"dennis@home" wrote in message
web.com...

See as far as teaching goes there are no differences between film
and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when you
teach the subject.


Whisky Dave has given several things that you need to be aware of when using
film, such as

- reciprocity failure at extreme shutter speeds
- need to choose the film type (eg speed, manufacturer, B&W/colour,
slide/neg) before shooting

This raises an interesting philosophical question: do you need to know about
film (and the limitations and issues that only affect film and not digital)
in order to know about photography nowadays?

I would never go so far as to say that film is an obsolete photographic
medium (in the same way that I wouldn't describe vinyl as an obsolete
sound-recording medium), but it's becoming more of a niche product.

Is there anything about photography (the creation of pictures using light)
which you would lose if you didn't teach about film-specific issues like
reciprocity, different light curves of different makes of film, the need to
choose the speed of film before you start shooting, given that these are not
relevant to digital.

Choice of colour v black and white is an after-shooting post-processing
issue with digital (indeed the photographer who took digital photos of my
wedding presented a few shots both in colour and monochrome, with
contrast-enhancement to emulate a B&W negative as opposed to straight
colour-to-monochrome conversion).

Choice of emulsion can be controlled after the event using programs that
alter the gamma curve to emulate different brands of colour slide and
negative film - again, deferring that decision until after shooting.

Choice of ISO speed can be made from shot to shot. When I used film I used
to wish I could do this. As a photographer you need to know why you don't
shoot everything at 3200 ASA (greatly increased noise, maybe different tonal
and colour representation though I can't detect any with my cameras), but
you don't need to decide on a fixed ASA for all shots.

It is not a deficiency of digital that some of these issues do not exist.
Some might even see it as a bonus that you have fewer restrictions like
this.

Of course if your pupils intend to use film as well as digital then they
need to be aware of them, but since most people will only ever use digital,
it may no longer be necessary to know about them, in the same way that we
don't need to know about choosing the correct amount of flash powder to use,
now that everyone uses electronic flash, and we don't need to use a tripod
for every single shot and the subject does not need to remain still for many
seconds now that film/digital sensitivity is a lot higher than it once was.
Knowing that all these restrictions used to exist is probably sufficient.

For example my wedding photographer said that he no longer uses film for any
of his work (portrait, wedding, landscape, buildings, as far as I could see
from his portfolio) because digital allows him to do everything that film
could, but for a minimal per-exposure cost and with fewer restrictions such
as need to choose film before shooting, and inability to preview shots in
the field if necessary. As such, knowledge of film is starting to become
unnecessary.

I must admit in some ways I regret the passing of film: there is something
evocative about the smell of a box of slides or a wallet of prints; the
noise of the projector; watching slides in a darkened room on a silver
screen; the way that a slide would occasionally go out of focus as the
projector lens started to "hunt". And the moment of anticipation when you
first opened the box of slides or the wallet of prints - remembering what
you had taken pictures of, maybe several weeks/months ago, wondering whether
such-and-such tricky shot had "worked" (ie whether you'd estimated the
non-metered exposure correctly).

But I wouldn't want to go back to those days.

On 30/09/2015 12:15, whisky-dave wrote:


I have a DoF mark on my camera.
You don't even know what that is do you, or what it's for.

Well you don't as its not a DoF mark.

Before you teach photography learn something about cameras.

On 30/09/2015 16:32, NY wrote:
"whisky-dave" wrote in message
...
In fact I have 2 DoF marks on my film camera. But I bet you don't
know what they are for.

So do mine on my digital.


which one is that then. ?

you can't even work that out !

what does the sentance "So do mine on my digital"

Are you refering to the DoF marks tatooed on your penis.

your digital what.....

Since someone (I think it was you but I'm not certain of the quoting)
said "I have two DoF marks on my film camera" and someone else replied
to that with "So do mine on my digital" I presume the latter was
referring to a digital *camera* since a camera is what you referred to
previously. Standard rules of English that you don't always need to
repeat the noun..

You are wasting your time, he mangled the quoting so much that he put
the they are on the lenses somewhere that the reply didn't make sense.

I expect he did it deliberately.

The so called DoF mark on his camera is almost certainly the line
through a circle that marks the plane of the film and not a DoF mark at all.

Lenses have pairs of DoF lines on them and they are curved along the
barrel on zooms. There may be one for each aperture but not always and
then you have to estimate.

He has probably never seen a Olympus or Sigma lens so he won't know
what's on them.

He has no idea about modern cameras which is why he doesn't want to
teach with them.

On 30/09/2015 17:07, whisky-dave wrote:

Wrong.
mine is ON THE CAMERA but to understand this with film you have to know what the mark represents.

Nothing to do with DoF.


As to the two marks, my first thought is visible and infra-red, unless they
are for the two extremes of a zoom lens (narrower DoF for same aperture at
longer focal length). For visible/IR, I presume as well as two DoF marks
there are two focus marks and that the different pairs of DoF marks are
roughly equally spaced about the respective focus mark.

No.


Have I understood your question correctly? Are the two sets of DoF marks
(and also the marks for the different focus points) in different colours?
That's usually the convention for visible/IR.

I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.



So why do you insist on calling it DoF, its not depth of focus either it
is just the position of the film plane which you need to know if you are
using a tape measure to set focus like you might for macro work.

BTW depth of focus depends on the lens attached, you should read more
http://www.usa.canon.com/cusa/profes...nge_depthfield


Oh and look they the mark on digital cameras too
http://www.dpreview.com/reviews/Olym...s/inhand02.jpg

Yes I have one of these to go with my Pentax MX and Sony a580 which also
have them.

You really don't know about cameras do you?

On 30/09/2015 17:50, NY wrote:
"whisky-dave" wrote in message
...
I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like
the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film
will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.

Ah! I didn't appreciate that your use of "DoF" wasn't referring to depth
of field, as I think a lot of other people had been using that
abbreviation earlier in the thread, but instead referred to depth of
focus, more commonly called focal plane. I wonder how many other people
made the same misunderstanding of what you were saying. If you'd
mentioned the crucial detail about "London Underground sign" I'd have
known what you meant and realised that you really *did* mean on the
camera rather than on the lens.

That mark has nothing to do with DoF in either meaning.
DoF is just the cone of light at the image plane and it is the
acceptable size at which it is deemed to be infocus. It varies with
lenses just like depth of field.


Now I wonder why you have *two* of those marks. Given that the plane of
both visible and IR film will be the same, it's nothing to do with that.
What could the second mark relate to? I'm even more puzzled because in
http://www.mir.com.my/rb/photography...topviewblk.jpg
I can only see one mark.


He is trying to bull**** but he doesn't know that we know more about
photography than he does.


By the way, digital cameras have the same mark as well, marking the
equivalent place: the location of the sensor as opposed to the film - eg
http://imaging.nikon.com/lineup/dslr/basics/19/04.htm which relates to
DSLRs.

On 30/09/2015 19:16, NY wrote:
"dennis@home" wrote in message
web.com...

See as far as teaching goes there are no differences between
film and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when
you teach the subject.


Whisky Dave has given several things that you need to be aware of
when using film, such as

- reciprocity failure at extreme shutter speeds - need to choose the
film type (eg speed, manufacturer, B&W/colour, slide/neg) before
shooting

So far he has only given differences that we have told him about.
I don't actually think he knows any.


This raises an interesting philosophical question: do you need to
know about film (and the limitations and issues that only affect film
and not digital) in order to know about photography nowadays?

I would never go so far as to say that film is an obsolete
photographic medium (in the same way that I wouldn't describe vinyl
as an obsolete sound-recording medium), but it's becoming more of a
niche product.

I would say vinyl is obsolete as a recording medium, some still use it
for playback but I doubt if many cut vinyl these days.


Is there anything about photography (the creation of pictures using
light) which you would lose if you didn't teach about film-specific
issues like reciprocity, different light curves of different makes of
film, the need to choose the speed of film before you start shooting,
given that these are not relevant to digital.

They aren't very relevant to most photography as most people would
correct for them in printing and there isn't much you can do when taking
the picture without adding extra light.


Choice of colour v black and white is an after-shooting
post-processing issue with digital (indeed the photographer who took
digital photos of my wedding presented a few shots both in colour and
monochrome, with contrast-enhancement to emulate a B&W negative as
opposed to straight colour-to-monochrome conversion).

Choice of emulsion can be controlled after the event using programs
that alter the gamma curve to emulate different brands of colour
slide and negative film - again, deferring that decision until after
shooting.

There aren't many emulsions that you can easily get these days.


Choice of ISO speed can be made from shot to shot. When I used film I
used to wish I could do this. As a photographer you need to know why
you don't shoot everything at 3200 ASA (greatly increased noise,
maybe different tonal and colour representation though I can't detect
any with my cameras), but you don't need to decide on a fixed ASA for
all shots.

It is not a deficiency of digital that some of these issues do not
exist. Some might even see it as a bonus that you have fewer
restrictions like this.

Of course if your pupils intend to use film as well as digital then
they need to be aware of them, but since most people will only ever
use digital, it may no longer be necessary to know about them, in the
same way that we don't need to know about choosing the correct amount
of flash powder to use, now that everyone uses electronic flash, and
we don't need to use a tripod for every single shot and the subject
does not need to remain still for many seconds now that film/digital
sensitivity is a lot higher than it once was. Knowing that all these
restrictions used to exist is probably sufficient.


A five minute talk will tell you all about the differences.

For example my wedding photographer said that he no longer uses film
for any of his work (portrait, wedding, landscape, buildings, as far
as I could see from his portfolio) because digital allows him to do
everything that film could, but for a minimal per-exposure cost and
with fewer restrictions such as need to choose film before shooting,
and inability to preview shots in the field if necessary. As such,
knowledge of film is starting to become unnecessary.

Digital has exceeded the quality of film for a few years, that's why
very few film cameras are sold. There is nothing a film camera can do
that can't be done on a digital camera and you can restrict yourself to
doing what a film camera can do if you want to.


I must admit in some ways I regret the passing of film: there is
something evocative about the smell of a box of slides or a wallet of
prints; the noise of the projector; watching slides in a darkened
room on a silver screen; the way that a slide would occasionally go
out of focus as the projector lens started to "hunt". And the moment
of anticipation when you first opened the box of slides or the wallet
of prints - remembering what you had taken pictures of, maybe several
weeks/months ago, wondering whether such-and-such tricky shot had
"worked" (ie whether you'd estimated the non-metered exposure
correctly).

But I wouldn't want to go back to those days.

I might dig some film out of the freezer and run a roll through my Nikon
SLR if i can find a battery as it doesn't work without one.
I could use the MX but I don't have any 35mm film.

"dennis@home" wrote in message
web.com...
I would never go so far as to say that film is an obsolete
photographic medium (in the same way that I wouldn't describe vinyl
as an obsolete sound-recording medium), but it's becoming more of a
niche product.

I would say vinyl is obsolete as a recording medium, some still use it
for playback but I doubt if many cut vinyl these days.

The only record that I've heard that was recorded to vinyl (well, actually
shellac on aluminium) was a recording made by the BBC of a talk that my
grandpa made on Children's Hour, probably some time in the 1950s. It is
notable for the weird more-posh-that-Mr-Cholmondley-Warner voice that my
grandpa puts on, under sufference, to mask his own "educated West Riding"
Yorkshire accent. He was talking about how steam trains work and comes out
with the phrase "end now the steam is caming aout of the chimney laike an
ballett fram a gan" (and now the steam is coming out of the chimney like a
bullet from a gun) - forever after we used to tease him about "a ballet fram
a gan". Knowing grandpa, he was hamming it up as a protest against the daft
rules which said that little children in Chobham or Weybridge wouldn't
understand anyone who didn't speak in a Home Counties accent.

Vinyl is niche, like film: it has its devotees who prefer it, but the
convenience and superior sound quality (eg lack of hiss and scratches,
better frequency response and dynamic range) of CD make it a no-brainer to
go for. MP3 has been a backward step, because it allows lossy compression
and all the horrible artefacts that this introduces (like JPEG for pictures)
but a lightly compressed MP3 (eg 192 kbps or higher) sounds
indistinguishable to my ears to a CD.

Is there anything about photography (the creation of pictures using
light) which you would lose if you didn't teach about film-specific
issues like reciprocity, different light curves of different makes of
film, the need to choose the speed of film before you start shooting,
given that these are not relevant to digital.

They aren't very relevant to most photography as most people would correct
for them in printing and there isn't much you can do when taking the
picture without adding extra light.


Choice of colour v black and white is an after-shooting
post-processing issue with digital (indeed the photographer who took
digital photos of my wedding presented a few shots both in colour and
monochrome, with contrast-enhancement to emulate a B&W negative as
opposed to straight colour-to-monochrome conversion).

Choice of emulsion can be controlled after the event using programs
that alter the gamma curve to emulate different brands of colour
slide and negative film - again, deferring that decision until after
shooting.

There aren't many emulsions that you can easily get these days.

It's ages since I've bought film. Kodachrome is no more, I believe, both in
terms of manufacture and Kodak labs to process it. Is Ektachrome still made?
I imagine if any slide film is still made, it will be something like
Ektachrome that can be processed by any competent lab. Negative film of
various speeds is probably still made, both B&W and colour? What about that
Ilford XP5 that was B&W but which used colour chemistry (eg the image was
made up of dye rather than silver)? That was amazingly fine-grained for 400
ASA, but it was a bugger to process consistently because of the higher
temperatures needed, but fortunately it seemed to tolerate a wide range of
under/over development!

And of course the cinema and TV industry still use negative film, though
there aren't many programmes that use it in preference to high def video.
"Lewis" still uses it (I went to watch them filming scenes when I lived near
Oxford) but the cameraman said it was becoming rarer and cinematographers
who were used to (and preferred) film were becoming rarer.

Choice of ISO speed can be made from shot to shot. When I used film I
used to wish I could do this. As a photographer you need to know why
you don't shoot everything at 3200 ASA (greatly increased noise,
maybe different tonal and colour representation though I can't detect
any with my cameras), but you don't need to decide on a fixed ASA for
all shots.

It is not a deficiency of digital that some of these issues do not
exist. Some might even see it as a bonus that you have fewer
restrictions like this.

Of course if your pupils intend to use film as well as digital then
they need to be aware of them, but since most people will only ever
use digital, it may no longer be necessary to know about them, in the
same way that we don't need to know about choosing the correct amount
of flash powder to use, now that everyone uses electronic flash, and
we don't need to use a tripod for every single shot and the subject
does not need to remain still for many seconds now that film/digital
sensitivity is a lot higher than it once was. Knowing that all these
restrictions used to exist is probably sufficient.


A five minute talk will tell you all about the differences.

For example my wedding photographer said that he no longer uses film
for any of his work (portrait, wedding, landscape, buildings, as far
as I could see from his portfolio) because digital allows him to do
everything that film could, but for a minimal per-exposure cost and
with fewer restrictions such as need to choose film before shooting,
and inability to preview shots in the field if necessary. As such,
knowledge of film is starting to become unnecessary.

Digital has exceeded the quality of film for a few years, that's why very
few film cameras are sold. There is nothing a film camera can do that
can't be done on a digital camera and you can restrict yourself to doing
what a film camera can do if you want to.

What intrigued me about Whisky Dave's comments was that he seemed to imply
(though never elaborated) that you use aperture and shutter speed
differently for film than for digital, which was why it was better to learn
on film. At least I think that was the gist of his argument. Within a normal
range of shutter speeds, you used them identically. All the same rules
applied: a short shutter speed freezes motion, a long one allows it to blur;
a wide aperture gives a shallow DoF and hence separates the subject from the
background; a small aperture gives a large DoF. Halving the shutter speed
requires doubling the aperture (ie going from f8 to f5.6 - I'm surprised he
didn't know where the 1.4 factor came from). All that knowledge from one
medium can be transferred directly to the other.

I've never experienced reciprocity failure because the only photos I've
taken at long exposures (eg 10 sec) have been of lighted buildings etc at
night - situations where the light is too dim to use a meter, and there's
not just one correct exposure but a whole range according to personal
preference. When I took a series of slides of the Christmas lights and
floodlit buildings in Bristol when I was at university, using a blue filter
to correct for tungsten light on daylight slide film, I probably experienced
horrendous reciprocity failure since I was using exposures of a minute or
so, but since I was wildly guessing exposures anyway, and since most of the
lights were coloured rather than being white tungsten (and many were
discharge tubes which reproduce very oddly on film) I wouldn't have know if
there was a colour shift. It would have been more apparent if I'd been
taking photos in proper white light, eg metering at f 2.8 and then stopping
right down by n stops and simply applying the normal multiply-by-2^n factor
to the shutter speed.

Thank goodness digital is immune to reciprocity failure. As a test, I took a
photo in room light at wide aperture and maybe 1/20 second, and then through
almost-crossed polaroids as a crude neutral density filter and with the lens
stopped right down, resulting in an exposure of something like a minute. And
the brightness, contrast, colour and tonal range were indistinguishable; the
only way to tell the pictures apart was the greater DoF.

Talking of discharge tubes as a source of light, one thing that has changed
from the days of film is the horrible green tinge of photos taken under
fluorescent light. It's not down to auto white-balance because I've fixed my
digital camera on daylight and photos come out with either no colour cast if
the lights are daylight fluorescents (6500 K) or else with a pale orange
cast if warm white fluorescents are used (around 5000 K) - a less extreme
version of the stronger orange cast under tungsten (2000 for normal bulbs,
3000 for photographic lights). So the results with digital are more as the
physics of light would suggest. I wonder if there was something in
Kodachrome that reacted to the small amount of UV in fluorescents.

If you white balance off a sheet of paper, it's possible to take copies of
the same subject under a wide range of lights (room tungsten, fluorescents,
LEDs, sunlight, shade) and get results which are all very similar, apart
from a slight muting of some tones of red under fluorescent and LED because
these are not a continuous spectrum. Imagine the range of filters you'd have
to carry around to cope with all those different light sources on slide
film. Negative is less critical because they can (and do) correct at
printing - confession time: if room light was fairly dim I didn't even
bother with a blue filter which would have "stolen" about 2 stops of light,
and I used to let the printing take care of the adjustment.

And then there were the joys of push-processing. HP5 push-processed to 1600
ASA resulted in grain that made the pictures look like pencil sketches!
Ektachrome 160 tungsten pushed to 640 was vile: very saturated and very
contrasty, though in fairness the stage lighting was probably a bit harsh
and shadowy as well.

I must admit in some ways I regret the passing of film: there is
something evocative about the smell of a box of slides or a wallet of
prints; the noise of the projector; watching slides in a darkened
room on a silver screen; the way that a slide would occasionally go
out of focus as the projector lens started to "hunt". And the moment
of anticipation when you first opened the box of slides or the wallet
of prints - remembering what you had taken pictures of, maybe several
weeks/months ago, wondering whether such-and-such tricky shot had
"worked" (ie whether you'd estimated the non-metered exposure
correctly).

But I wouldn't want to go back to those days.

I might dig some film out of the freezer and run a roll through my Nikon
SLR if i can find a battery as it doesn't work without one.
I could use the MX but I don't have any 35mm film.

Yes, finding a battery for an old camera is always a problem. I had a film
in my film SLR which I forgot about after I got a digital camera, and only
discovered several years later. Because my camera was motor drive, there was
no way of rewinding the film other than with the motor, and the battery was
dead. I got the photo shop to remove the film rather than buying a battery
just to do that job! It was weird to see photos taken some five or six years
earlier!

I tried to sell the camera and lenses on eBay but all I got were offers of
50p or £1 which says a lot about what value people attach to film cameras
these days. Sad - it was a good camera (certainly lighter than my DSLR and
its long lens!) though I skimped on the lenses and forever after wished I'd
bought genuine Canon rather than third-party which had more pincushion
distortion than I'd have liked.

It's great with packages like PT Lens to be able to correct for lens
distortion like this: it picks up the make of camera and lens, the focal
length and aperture, and adjusts using its database of known lens
distortion. Purists might say that it's cheating and that you should buy a
more expensive lens in the first place, but zoom lenses will always have
*some* distortion somewhere in the range of focal lengths, and it's not
always practicable to change your position to alter the framing to match one
of your prime lenses.

On Thursday, 1 October 2015 09:44:52 UTC+1, NY wrote:

film. Negative is less critical because they can (and do) correct at
printing - confession time: if room light was fairly dim I didn't even
bother with a blue filter which would have "stolen" about 2 stops of light,
and I used to let the printing take care of the adjustment.

wise, I've suffered the result of too little blue light. At some point you get nothing but noise in the blue, making anywhere near proper colours impossible.

And then there were the joys of push-processing. HP5 push-processed to 1600
ASA resulted in grain that made the pictures look like pencil sketches!
Ektachrome 160 tungsten pushed to 640 was vile: very saturated and very
contrasty, though in fairness the stage lighting was probably a bit harsh
and shadowy as well.

Actually you can make some very nice pictures by pushing that effect to its limit. Get yourself a ton of grain in the negative, then push process the paper print after very heavily underexposing it. The result is many areas/details stay completely white, and what dark you get is extremely contrasty with heavy & saturated grain. It's hard to describe how it looks good, but it really does with the right subject. I used to love it for portrait - you need to get the shadowing right for it to really work well, as a lot of the scene detail is lost completely. It's a technique I've never seen anyone else use.


NT

On Wednesday, 30 September 2015 17:50:11 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the
london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film
will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.

Ah! I didn't appreciate that your use of "DoF" wasn't referring to depth of
field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do photography know of depth of field, when I stared in the 6th form I looked DoF up in a photography book.


as I think a lot of other people had been using that abbreviation
earlier in the thread, but instead referred to depth of focus, more commonly
called focal plane. I wonder how many other people made the same
misunderstanding of what you were saying. If you'd mentioned the crucial
detail about "London Underground sign" I'd have known what you meant and
realised that you really *did* mean on the camera rather than on the lens.


Now I wonder why you have *two* of those marks.

Well, ones Depth of Field, which is almost always on the lens and usually a little straight line mark rather than a symbol, and teh other is depth of focus which is an indication of where the film plane is, or where the film sits.


Given that the plane of both
visible and IR film will be the same, it's nothing to do with that.

wrong. IR focus at a differnt point to visable light.


What
could the second mark relate to? I'm even more puzzled because in
http://www.mir.com.my/rb/photography...topviewblk.jpg I
can only see one mark.

yes that's the flim/sensor plan, it's where the film is, so you can measure the flim to lens distance and even the film to subject distance.



By the way, digital cameras have the same mark as well, marking the
equivalent place: the location of the sensor as opposed to the film - eg
http://imaging.nikon.com/lineup/dslr/basics/19/04.htm which relates to
DSLRs.

But that isn;t a compact camera it has an interchangable lens.

On Wednesday, 30 September 2015 23:00:01 UTC+1, dennis@home wrote:
On 30/09/2015 17:07, whisky-dave wrote:

Wrong.
mine is ON THE CAMERA but to understand this with film you have to know what the mark represents.

Nothing to do with DoF.


As to the two marks, my first thought is visible and infra-red, unless they
are for the two extremes of a zoom lens (narrower DoF for same aperture at
longer focal length). For visible/IR, I presume as well as two DoF marks
there are two focus marks and that the different pairs of DoF marks are
roughly equally spaced about the respective focus mark.

No.


Have I understood your question correctly? Are the two sets of DoF marks
(and also the marks for the different focus points) in different colours?
That's usually the convention for visible/IR.

I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.



So why do you insist on calling it DoF,

I don;t insist, that;s what other have called it.

its not depth of focus either it
is just the position of the film plane which you need to know if you are
using a tape measure to set focus like you might for macro work.


BTW depth of focus depends on the lens attached, you should read more
http://www.usa.canon.com/cusa/profes...nge_depthfield

for video work.



Oh and look they the mark on digital cameras too
http://www.dpreview.com/reviews/Olym...s/inhand02.jpg

yep shows where the film or sensor plane is.


Yes I have one of these to go with my Pentax MX and Sony a580 which also
have them.

You really don't know about cameras do you?

mORE THAN YOU IT SEEMS.

wrote in message
...
On Thursday, 1 October 2015 09:44:52 UTC+1, NY wrote:

film. Negative is less critical because they can (and do) correct at
printing - confession time: if room light was fairly dim I didn't even
bother with a blue filter which would have "stolen" about 2 stops of
light,
and I used to let the printing take care of the adjustment.

wise, I've suffered the result of too little blue light. At some point you
get nothing but noise in the blue, making anywhere near proper colours
impossible.

Yes, you want to make sure you still get a reasonable amount of signal in
relation to the noise. It's like overexposing parts of a picture that's got
very contrasty light: once one or more of the channels reaches maximum you
get featureless colour (typically a blue sky becomes a horrible cyan, or
parts of the face become fake-tan orange). Any sensor (digital or film) has
its minimum and maximum values, and one of the few problems with digital is
that the maximum can be a bit of brick wall rather than a gradual roll-off,
which is why, as for slide film, I expose for the highlights and correct in
post-processing.

And then there were the joys of push-processing. HP5 push-processed to
1600
ASA resulted in grain that made the pictures look like pencil sketches!
Ektachrome 160 tungsten pushed to 640 was vile: very saturated and very
contrasty, though in fairness the stage lighting was probably a bit harsh
and shadowy as well.

Actually you can make some very nice pictures by pushing that effect to
its limit. Get yourself a ton of grain in the negative, then push process
the paper print after very heavily underexposing it. The result is many
areas/details stay completely white, and what dark you get is extremely
contrasty with heavy & saturated grain. It's hard to describe how it looks
good, but it really does with the right subject. I used to love it for
portrait - you need to get the shadowing right for it to really work well,
as a lot of the scene detail is lost completely. It's a technique I've
never seen anyone else use.

Sounds intriguing. It's sad that a package like Photoshop or PaintShop Pro
could achieve this with a few button presses whereas you really have to work
at it with film and feel as if you've really achieved something then.

I experimented with printing a slide onto B&W paper (which gives a negative)
and then contact printing this onto another piece of B&W paper (wait till
it's dry otherwise the emulsions stick together - been there!). Results can
be quite good for some subjects - you have to allow for the fact that the
"negative" will be very non-panchromatic so red/orange shades in the slide
render as white in the neg and hence black on the final positive. Printing
from colour negs yields horribly muddy results (and very long exposures)
because the orange base of the neg behaves as a safelight! The paper can
only see the reddish tones in the original picture (which come out as blue
on the neg), so it's like taking a B&W photo in red light.

whisky-dave wrote:

I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras

My dSLR also has one

(perhaps not all) it is where the film will lay aka film plane.

Or indeed, the plane of the sensor ...

On Wednesday, 30 September 2015 23:19:26 UTC+1, dennis@home wrote:
On 30/09/2015 19:16, NY wrote:
"dennis@home" wrote in message
web.com...

See as far as teaching goes there are no differences between
film and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when
you teach the subject.


Whisky Dave has given several things that you need to be aware of
when using film, such as

- reciprocity failure at extreme shutter speeds - need to choose the
film type (eg speed, manufacturer, B&W/colour, slide/neg) before
shooting

So far he has only given differences that we have told him about.
I don't actually think he knows any.

Nom I mentioned them before anyone elee .



This raises an interesting philosophical question: do you need to
know about film (and the limitations and issues that only affect film
and not digital) in order to know about photography nowadays?

I would never go so far as to say that film is an obsolete
photographic medium (in the same way that I wouldn't describe vinyl
as an obsolete sound-recording medium), but it's becoming more of a
niche product.

I would say vinyl is obsolete as a recording medium, some still use it
for playback but I doubt if many cut vinyl these days.

Few record to vinyl, but vinyl records are still made and sold.



Is there anything about photography (the creation of pictures using
light) which you would lose if you didn't teach about film-specific
issues like reciprocity, different light curves of different makes of
film, the need to choose the speed of film before you start shooting,
given that these are not relevant to digital.

They aren't very relevant to most photography as most people would
correct for them in printing and there isn't much you can do when taking
the picture without adding extra light.

You don't know much about this do you.



A five minute talk will tell you all about the differences.

but not explain them you can gove 5min talks on quantumm mechanics too.


Digital has exceeded the quality of film for a few years, that's why
very few film cameras are sold. There is nothing a film camera can do
that can't be done on a digital camera and you can restrict yourself to
doing what a film camera can do if you want to.

That is not the point though is it.

On 30/09/2015 19:16, NY wrote:
"dennis@home" wrote in message
web.com...

See as far as teaching goes there are no differences between film
and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when you
teach the subject.

Whisky Dave has given several things that you need to be aware of when
using
film, such as

- reciprocity failure at extreme shutter speeds
- need to choose the film type (eg speed, manufacturer, B&W/colour,
slide/neg) before shooting

And the colour temperature of the continuum light source. All bets are
off with film in narrowband or emission line based illumination.

It is mainly of historical interest CCDs get it right. It so happens
that panchromatic and colour emulsions have a safelight wavelength
sensitivity gap that exactly matches the bright green OIII nebula line
in many astronomical nebulae. This meant that until about the mid 1970's
when a special emulsion sensitive to this line was created all the
Palomar deep sky slides showed nebulae to be red, pink and powder blue
with no hint of green, yellow or turquoise.

It always seemed a bit odd that something that visually looked dirty
oily grey green photographed as mostly pink and blue.

This raises an interesting philosophical question: do you need to know
about
film (and the limitations and issues that only affect film and not digital)
in order to know about photography nowadays?

I would never go so far as to say that film is an obsolete photographic
medium (in the same way that I wouldn't describe vinyl as an obsolete
sound-recording medium), but it's becoming more of a niche product.

An interesting quirk of colour film is that to get flesh tones exactly
right in different parts of the world different makers bias their colour
films slightly differently (and so do digital cameras). The residual
errors are hidden along the line of purples which makes a few rare plant
flowers with just the wrong peak wavelength reflected look very strange
indeed when using film. Notocactus Ubelmannianus (purple form) is one
such plant that photographs badly on most colour films.

Digital images can easily have their white balance and flesh tones
tweaked afterwards if necessary and the residual colour errors are also
considerably less than film on decent kit.

Is there anything about photography (the creation of pictures using light)
which you would lose if you didn't teach about film-specific issues like
reciprocity, different light curves of different makes of film, the need to
choose the speed of film before you start shooting, given that these are
not relevant to digital.

Choosing the speed can still be relevant in digital if you want to
deliberately create a motion blur or freeze fast action. You are always
trading signal to noise for shorter exposures (courser grain in film and
more intrusive thermal noise/less resolution on a digital camera).

One thing a one shot colour camera struggles with is monochromatic
images at certain wavelengths. Some sensors really don't like red
H-alpha and leaks in the other filtered channels gives a weird effect.

Choice of colour v black and white is an after-shooting post-processing
issue with digital (indeed the photographer who took digital photos of my
wedding presented a few shots both in colour and monochrome, with
contrast-enhancement to emulate a B&W negative as opposed to straight
colour-to-monochrome conversion).

Choice of emulsion can be controlled after the event using programs that
alter the gamma curve to emulate different brands of colour slide and
negative film - again, deferring that decision until after shooting.

You could do some of these things by scanning slides or negatives back
when film was the only high resolution game in town.

Choice of ISO speed can be made from shot to shot. When I used film I used
to wish I could do this. As a photographer you need to know why you don't
shoot everything at 3200 ASA (greatly increased noise, maybe different
tonal
and colour representation though I can't detect any with my cameras), but
you don't need to decide on a fixed ASA for all shots.

You could in the old days push process film or bake it in a dry N2/H2
gas mix for a day or two before use to trade shelf life for sensitivity.
You didn't have to develop it exactly by the book.

In extremis uranium intensifier could sometimes rescue faint under
exposed silver based images to printable negatives.

It is not a deficiency of digital that some of these issues do not exist.
Some might even see it as a bonus that you have fewer restrictions like
this.

The main advantage of digital especially in hard to repeat situations is
that you have instant feedback and know almost immediately whether or
not you have a decent quality record of the event.

We used to carry a Polaroid instant camera around with negative capable
film stock as an insurance policy when taking important images.

Polaroid was doomed the moment that Mpixel digicams became affordable.

--
Regards,
Martin Brown

"whisky-dave" wrote in message
...
Ah! I didn't appreciate that your use of "DoF" wasn't referring to depth
of
field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I looked
DoF up in a photography book.

I'd never heard of depth of focus but a quick google has educated me on
that. Strictly speaking the "London Underground" sign marks the position of
the film, rather than the range of positions of the film where the lens
would produce an acceptably sharp image, which I'm sure isn't a constant and
varies according to focal length of lens.


Now I wonder why you have *two* of those marks.

Well, ones Depth of Field, which is almost always on the lens and usually
a little straight line mark rather than a symbol, and teh other is depth
of focus which is an indication of where the film plane is, or where the
film sits.

I was misled by the way you phrased it into thinking that they were
alongside each other, either on the lens or the camera, rather than being
two completely different things which happen to share the same acronym.


Given that the plane of both
visible and IR film will be the same, it's nothing to do with that.

wrong. IR focus at a differnt point to visable light.

Yes, but the difference isn't a constant for all lenses so you couldn't mark
it by a different film plane Underground mark on the camera. Instead you'd
measure from the film plane to the subject and then set your lens to the
measured distance using the IR mark on the lens rather than the visible
mark. Or if you were focussing using the viewfinder, you'd focus using
optical light, read the distance against the visible mark and re-focus
slightly to set that same distance against the IR mark.


By the way, digital cameras have the same mark as well, marking the
equivalent place: the location of the sensor as opposed to the film - eg
http://imaging.nikon.com/lineup/dslr/basics/19/04.htm which relates to
DSLRs.

But that isn't a compact camera it has an interchangable lens.

I never said it was a compact camera. I should have modified what I said to
"digital *SLR* cameras have the same mark" to clarify that. Mind you, I have
seen a compact camera with a focal plane mark - I've no idea what make/model
it was, but I remember noticing it at the time. And some video camcorders
have the mark as well (as had some Super 8 film cameras).

How standard is it for the tripod mounting thread to be aligned with the
focal plane and the centre of the sensor/film so the camera always rotates
about the sensor/film? Looking at the three DSLRs that I can lay my hands on
right now, the tripod bush looks to be in about the right place (*) but on
my two compact digital cameras it's a fair way off to one side; I'm not sure
whether the Instamatic-type film camera that I used to have even had a
tripod mount.

(*) It's about the right distance front-to-back to line up with the focal
plane mark and it's roughly aligned left-to-right with the middle of the
lens mount.

On Thursday, 1 October 2015 11:11:29 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
Ah! I didn't appreciate that your use of "DoF" wasn't referring to depth
of
field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I looked
DoF up in a photography book.

I'd never heard of depth of focus but a quick google has educated me on
that. Strictly speaking the "London Underground" sign marks the position of
the film, rather than the range of positions of the film.
I think early cameras such as plate it was importan to make sure the plate was in teh right place eraly cameras weren't acurratly made.


where the lens
would produce an acceptably sharp image, which I'm sure isn't a constant and
varies according to focal length of lens.

I don;t think it does. if yuo have any camera with interchangable lens all of tehm have to be in focus at the same point and that is where the film or sensor is. In the old days yuo could take the film pack out and replace it.
If teh fiml/sensor is in teh wrong place the picture will be out of focus.
Those with difital camera don;t consioder this and probley have never even throught about it.



Now I wonder why you have *two* of those marks.

Well, ones Depth of Field, which is almost always on the lens and usually
a little straight line mark rather than a symbol, and teh other is depth
of focus which is an indication of where the film plane is, or where the
film sits.

I was misled by the way you phrased it into thinking that they were
alongside each other, either on the lens or the camera, rather than being
two completely different things which happen to share the same acronym.

Well I've yet to see a use for this in the digital photography world.
I've yet to see a compact with this mark, well a compact that doesn;t have interchangable lenses.




Given that the plane of both
visible and IR film will be the same, it's nothing to do with that.

wrong. IR focus at a differnt point to visable light.

Yes, but the difference isn't a constant for all lenses.

it's mostly a function of focal lenth.

so you couldn't mark
it by a different film plane Underground mark on the camera.

I know which is why I say it has nothing to do with the lens, which is why it's on the camera, and why they put IR marks on lenes mostly telephoto rather than WA.

Instead you'd
measure from the film plane to the subject and then set your lens to the
measured distance using the IR mark on the lens rather than the visible
mark. Or if you were focussing using the viewfinder, you'd focus using
optical light, read the distance against the visible mark and re-focus
slightly to set that same distance against the IR mark.

Yep that's how I did it. I never used the DoFocus mark for IR.
I used it a few times for macro when calculatign guide No.s
but I found trial an error worked best.

By the way, digital cameras have the same mark as well, marking the
equivalent place: the location of the sensor as opposed to the film - eg
http://imaging.nikon.com/lineup/dslr/basics/19/04.htm which relates to
DSLRs.

But that isn't a compact camera it has an interchangable lens.

I never said it was a compact camera. I should have modified what I said to
"digital *SLR* cameras have the same mark" to clarify that. Mind you, I have
seen a compact camera with a focal plane mark - I've no idea what make/model
it was, but I remember noticing it at the time. And some video camcorders
have the mark as well (as had some Super 8 film cameras).

It does seem that those that have experince of film know far more about these marks than those brought upo on digital cameras.


How standard is it for the tripod mounting thread to be aligned with the
focal plane.

I'd say never but I've never seen one.

and the centre of the sensor/film so the camera always rotates
about the sensor/film? Looking at the three DSLRs that I can lay my hands on
right now, the tripod bush looks to be in about the right place (*) but on
my two compact digital cameras it's a fair way off to one side; I'm not sure
whether the Instamatic-type film camera that I used to have even had a
tripod mount.

Can;t see the3 point of doing that the tripod mount should be so the camera balancies better on the tripod and not stressing anyhting.
It's why you have tripod mounts on telephoto lenses and not normally on WA ones.


(*) It's about the right distance front-to-back to line up with the focal
plane mark and it's roughly aligned left-to-right with the middle of the
lens mount.

irrelivent to film or sensors the tripod mount is about balance
or it's most convient to put it.

On Wednesday, 30 September 2015 22:32:38 UTC+1, dennis@home wrote:
On 30/09/2015 12:15, whisky-dave wrote:


I have a DoF mark on my camera.
You don't even know what that is do you, or what it's for.

Well you don't as its not a DoF mark.

Before you teach photography learn something about cameras.

It is a DoF mark that's what it's called that's what it is.

On 01/10/2015 10:25, whisky-dave wrote:
On Wednesday, 30 September 2015 17:50:11 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
I have a canon A1 film camera. http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little
like the london underground logo.

This is the DoF mark, for the camera, it's Not Depth of Field,
but Depth of Focus. It only appears on film cameras (perhaps not
all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth
of Field.

Ah! I didn't appreciate that your use of "DoF" wasn't referring to
depth of field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I
looked DoF up in a photography book.

Well go and read it again because you have it wrong.



as I think a lot of other people had been using that abbreviation
earlier in the thread, but instead referred to depth of focus, more
commonly called focal plane. I wonder how many other people made
the same misunderstanding of what you were saying. If you'd
mentioned the crucial detail about "London Underground sign" I'd
have known what you meant and realised that you really *did* mean
on the camera rather than on the lens.


Now I wonder why you have *two* of those marks.

Well, ones Depth of Field, which is almost always on the lens and
usually a little straight line mark rather than a symbol, and teh
other is depth of focus which is an indication of where the film
plane is, or where the film sits.

That has nothing to do with either DoF.



Given that the plane of both visible and IR film will be the same,
it's nothing to do with that.

wrong. IR focus at a differnt point to visable light.

That depends on the lens, The focal length has to be corrected for all
the colours and you can correct for IR too but its usually only done for
specialist uses. A mirror lens will bring all the colours including IR
to the same focus.



What could the second mark relate to? I'm even more puzzled because
in
http://www.mir.com.my/rb/photography...topviewblk.jpg
I can only see one mark.

yes that's the flim/sensor plan, it's where the film is, so you can
measure the flim to lens distance and even the film to subject
distance.

Well you got that bit right.




By the way, digital cameras have the same mark as well, marking
the equivalent place: the location of the sensor as opposed to the
film - eg http://imaging.nikon.com/lineup/dslr/basics/19/04.htm
which relates to DSLRs.

But that isn;t a compact camera it has an interchangable lens.


So what?

On 01/10/2015 10:36, whisky-dave wrote:
On Wednesday, 30 September 2015 23:00:01 UTC+1, dennis@home wrote:
On 30/09/2015 17:07, whisky-dave wrote:

Wrong.
mine is ON THE CAMERA but to understand this with film you have to know what the mark represents.

Nothing to do with DoF.


As to the two marks, my first thought is visible and infra-red, unless they
are for the two extremes of a zoom lens (narrower DoF for same aperture at
longer focal length). For visible/IR, I presume as well as two DoF marks
there are two focus marks and that the different pairs of DoF marks are
roughly equally spaced about the respective focus mark.

No.


Have I understood your question correctly? Are the two sets of DoF marks
(and also the marks for the different focus points) in different colours?
That's usually the convention for visible/IR.

I have a canon A1 film camera.
http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little like the london underground logo.

This is the DoF mark, for the camera,
it's Not Depth of Field, but Depth of Focus.
It only appears on film cameras (perhaps not all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.



So why do you insist on calling it DoF,

I don;t insist, that;s what other have called it.

Who?
Have you corrected them yet?


its not depth of focus either it
is just the position of the film plane which you need to know if you are
using a tape measure to set focus like you might for macro work.


BTW depth of focus depends on the lens attached, you should read more
http://www.usa.canon.com/cusa/profes...nge_depthfield

for video work.

Irrelevant, they are the same.




Oh and look they the mark on digital cameras too
http://www.dpreview.com/reviews/Olym...s/inhand02.jpg

yep shows where the film or sensor plane is.


Yes I have one of these to go with my Pentax MX and Sony a580 which also
have them.

You really don't know about cameras do you?

mORE THAN YOU IT SEEMS.

So how come you keep getting stuff wrong?

On 01/10/2015 10:54, whisky-dave wrote:
On Wednesday, 30 September 2015 23:19:26 UTC+1, dennis@home wrote:
On 30/09/2015 19:16, NY wrote:
"dennis@home" wrote in message
web.com...

See as far as teaching goes there are no differences between
film and digital unless you decide to use them.

So I'm right there sis a differnce even more significant when
you teach the subject.


Whisky Dave has given several things that you need to be aware of
when using film, such as

- reciprocity failure at extreme shutter speeds - need to choose the
film type (eg speed, manufacturer, B&W/colour, slide/neg) before
shooting

So far he has only given differences that we have told him about.
I don't actually think he knows any.

Nom I mentioned them before anyone elee .



This raises an interesting philosophical question: do you need to
know about film (and the limitations and issues that only affect film
and not digital) in order to know about photography nowadays?

I would never go so far as to say that film is an obsolete
photographic medium (in the same way that I wouldn't describe vinyl
as an obsolete sound-recording medium), but it's becoming more of a
niche product.

I would say vinyl is obsolete as a recording medium, some still use it
for playback but I doubt if many cut vinyl these days.

Few record to vinyl, but vinyl records are still made and sold.



Is there anything about photography (the creation of pictures using
light) which you would lose if you didn't teach about film-specific
issues like reciprocity, different light curves of different makes of
film, the need to choose the speed of film before you start shooting,
given that these are not relevant to digital.

They aren't very relevant to most photography as most people would
correct for them in printing and there isn't much you can do when taking
the picture without adding extra light.

You don't know much about this do you.

I know why it happens, do you want to explain it or me?

A five minute talk will tell you all about the differences.

but not explain them you can gove 5min talks on quantumm mechanics too.

One is simple the other is even simpler.

Digital has exceeded the quality of film for a few years, that's why
very few film cameras are sold. There is nothing a film camera can do
that can't be done on a digital camera and you can restrict yourself to
doing what a film camera can do if you want to.

That is not the point though is it.

No the point is that you can teach photography easier and cover more
using digital rather than film.
You can't teach darkroom techniques using digital.
You still maintain there are enough differences between film and digital
to make it difficult to use digital but refuse to say what they are and
keep getting the basics wrong and claim its not you that's wrong. Not
very promising for your pupils is it.

On Thursday, 1 October 2015 12:56:50 UTC+1, dennis@home wrote:
On 01/10/2015 10:25, whisky-dave wrote:
On Wednesday, 30 September 2015 17:50:11 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
I have a canon A1 film camera. http://tinyurl.com/phjla58

just to the left of the hotshoe the symbol that looks s little
like the london underground logo.

This is the DoF mark, for the camera, it's Not Depth of Field,
but Depth of Focus. It only appears on film cameras (perhaps not
all) it is where the film will lay aka film plane.

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth
of Field.

Ah! I didn't appreciate that your use of "DoF" wasn't referring to
depth of field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I
looked DoF up in a photography book.

Well go and read it again because you have it wrong.

then prove you're not talking ******** oh you can;t.

http://www.videomaker.com/article/13...depth-of-focus

DEPTH OF FIELD - The range of object distance within which objects are in satisfactory sharp focus, the limits being the establishment of a circle of confusion of greatest acceptable size.
DEPTH OF FOCUS - The range through which the image plane (the emulsion of the film) can be moved backward and forward with respect to the camera lens such as defined under the depth of field and circle of confusion. This term is often confused with depth of field and vice versa.

In common English, Depth of Field is what the photographer is interested in; it is what is in acceptable focus in front of the lens. Depth of Focus is what only a technician is interested in; it is what is in focus behind the rear lens element which the film or image sensor "sees."

as I think a lot of other people had been using that abbreviation
earlier in the thread, but instead referred to depth of focus, more
commonly called focal plane. I wonder how many other people made
the same misunderstanding of what you were saying. If you'd
mentioned the crucial detail about "London Underground sign" I'd
have known what you meant and realised that you really *did* mean
on the camera rather than on the lens.


Now I wonder why you have *two* of those marks.

Well, ones Depth of Field, which is almost always on the lens and
usually a little straight line mark rather than a symbol, and teh
other is depth of focus which is an indication of where the film
plane is, or where the film sits.

That has nothing to do with either DoF.

Yes it has.



Given that the plane of both visible and IR film will be the same,
it's nothing to do with that.

wrong. IR focus at a differnt point to visable light.

That depends on the lens,

not it doesn't IR always focus at a differnt point it's to do with the way light refracts through a glass lens.
Of course I realise you know NOTHING about such things.


The focal length has to be corrected for all.
No the foacl lenght doesn;t need correcting.

the colours and you can correct for IR too but its usually only done for
specialist uses.

What do you mean by specialst use's you've no idea have you.
Have you ever used IR flim ?
Didn;t think so.

A mirror lens will bring all the colours including IR
to the same focus.

Mirror lenes aren't the standard lens for most cameras.


What could the second mark relate to? I'm even more puzzled because
in
http://www.mir.com.my/rb/photography...topviewblk.jpg
I can only see one mark.

yes that's the flim/sensor plan, it's where the film is, so you can
measure the flim to lens distance and even the film to subject
distance.

Well you got that bit right.

I got it all right.

On Thursday, 1 October 2015 13:00:49 UTC+1, dennis@home wrote:
On 01/10/2015 10:36, whisky-dave wrote:

I think it was a hang on from the old days before SLR focusing.
This mark has NOTHING to do with the lens attached unlike Depth of Field.



So why do you insist on calling it DoF,

I don;t insist, that;s what other have called it.

Who?

Anyone that knows about what photography is.
Those that think smart phones invented photography need educating.


Have you corrected them yet?

you're the one that needs correcting.




its not depth of focus either it
is just the position of the film plane which you need to know if you are
using a tape measure to set focus like you might for macro work.


BTW depth of focus depends on the lens attached, you should read more
http://www.usa.canon.com/cusa/profes...nge_depthfield

for video work.

Irrelevant, they are the same.

they are NOT the same.

DEPTH OF FIELD - The range of object distance within which objects are in satisfactory sharp focus, the limits being the establishment of a circle of confusion of greatest acceptable size.
DEPTH OF FOCUS - The range through which the image plane (the emulsion of the film) can be moved backward and forward with respect to the camera lens such as defined under the depth of field and circle of confusion. This term is often confused with depth of field and vice versa.

In common English, Depth of Field is what the photographer is interested in; it is what is in acceptable focus in front of the lens. Depth of Focus is what only a technician is interested in; it is what is in focus behind the rear lens element which the film or image sensor "sees."


So how come you keep getting stuff wrong?

I don't.

On Thursday, 1 October 2015 13:08:31 UTC+1, dennis@home wrote:
On 01/10/2015 10:54, whisky-dave wrote:


Is there anything about photography (the creation of pictures using
light) which you would lose if you didn't teach about film-specific
issues like reciprocity, different light curves of different makes of
film, the need to choose the speed of film before you start shooting,
given that these are not relevant to digital.

They aren't very relevant to most photography as most people would
correct for them in printing and there isn't much you can do when taking
the picture without adding extra light.

You don't know much about this do you.

I know why it happens, do you want to explain it or me?

you, don't make me laugh you haven't a clue.

it wasn't me that said the above "they aren;t..... either.




A five minute talk will tell you all about the differences.

but not explain them you can gove 5min talks on quantumm mechanics too.

One is simple the other is even simpler.

and there's few as simple as yuo .


Digital has exceeded the quality of film for a few years, that's why
very few film cameras are sold. There is nothing a film camera can do
that can't be done on a digital camera and you can restrict yourself to
doing what a film camera can do if you want to.

That is not the point though is it.

No the point is that you can teach photography easier and cover more
using digital rather than film.

You canm but it deosn't work like that.

ou know nothing about teaching do you.


You can't teach darkroom techniques using digital.

You could but it wouldn;lt be any better than using a flight similar
to get someone their pilots licence.


You still maintain there are enough differences between film and digital
to make it difficult to use digital but refuse to say what they are and
keep getting the basics wrong and claim its not you that's wrong. Not
very promising for your pupils is it.

I've told you what they were, because you have NEVER been in a teaching enviroment you will NEVER understand.

"whisky-dave" wrote in message
...
On Thursday, 1 October 2015 11:11:29 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
Ah! I didn't appreciate that your use of "DoF" wasn't referring to
depth
of
field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I
looked
DoF up in a photography book.

I'd never heard of depth of focus but a quick google has educated me on
that. Strictly speaking the "London Underground" sign marks the position
of
the film, rather than the range of positions of the film.
I think early cameras such as plate it was importan to make sure the plate
was in teh right place eraly cameras weren't acurratly made.


where the lens
would produce an acceptably sharp image, which I'm sure isn't a constant
and
varies according to focal length of lens.

I don;t think it does. if yuo have any camera with interchangable lens all
of tehm have to be in focus at the same point and that is where the film
or sensor is. In the old days yuo could take the film pack out and replace
it.
If teh fiml/sensor is in teh wrong place the picture will be out of focus.
Those with difital camera don;t consioder this and probley have never even
throught about it.

I doubt whether anyone with a camera with a fixed and defined focal plane
(eg the polished plate across which the film runs, with the 36x24 mm or
120-sized aperture in it) will have thought much about it. After all, the
position of the focal plane is no more adjustable for most film cameras than
for a digital camera.

Where the focal plane mark comes into its own is if you are setting focus of
your lens by tape measure rather than by adjusting the focus ring until the
correct part of the image is in focus on the focussing screen (or letting
the auto-focus do its job).

How certain are you that "depth of focus mark" is the correct term for the
"underground symbol" mark? In camera manuals it's described as "focal
plane". Depth of focus (like depth of field) refers to a *range* of
distances - either side of the focal plane (in the case of depth of focus)
or either side of the subject (in the case of depth of field):
https://encrypted-tbn2.gstatic.com/i...My4vO0bTwyLldN

It is probably technically incorrect to refer to the "underground mark" as
"the depth of focus mark" (because this is a range rather than an absolute
distance) but nevertheless it may be that it is common parlance. If so, fair
enough, although all the references I've seen to the mark on cameras have
called it the focal plane mark.


Since the rigidity of the camera body keeps the lens perpendicular to the
sensor/film and the correct distance away, depth of focus isn't really an
issue for cameras unless you use bellows between lens and film. Position of
focal plane is another matter and you'd use it for specialised focussing as
I described earlier.


I doubt whether all lenses focus IR the same distance closer/further than
visible light. My gut feeling is that it may vary depending on the quality
of the lens (as well, almost certainly, on the focal length). Here's why. A
simple lens made of a single piece of glass focuses different colours of
light at different distances, which results in chromatic aberration. To
counteract this, photographic and telescope lenses have elements made of a
combination of two pieces of glass of different refractive index to minimise
the difference. In general, the more you pay for a lens, the less chromatic
aberration you'll get - ie the smaller will be the depth of focus between
the red and violet ends of the spectrum. Extending this further, a good lens
will correct over a wider range, extending to some part of the IR spectrum.
It may not do it perfectly, but the degree to which it does governs how far
apart in depth the lens will focus visible and IR. For this reason, and the
fact that as you say a longer lens probably has a greater offset between IR
and visible focal planes, I'd expect it to make sense only to mark the two
focus points on the lens focussing scale and not on the camera.

Effectively the underground mark is saying "this is where the sensor/film
is". A lens's focussing scale is marked such that a visible light image will
be focussed at the plane, by virtue of the camera having a fixed and
precisely controlled spacing between mount and film. For IR, a different
lens-dependent offset is needed to counteract the fact that when the lens is
correctly focussed for visible light, IR will be focussed at a different
plane *whose position depends on the lens* both in terms of focal length and
degree of chromatic aberration correction.



How standard is it for the tripod mounting thread to be aligned with the
focal plane.

I'd say never but I've never seen one.

Can;t see the3 point of doing that the tripod mount should be so the
camera balancies better on the tripod and not stressing anyhting.
It's why you have tripod mounts on telephoto lenses and not normally on WA
ones.

The only time when the precise position of the tripod mount is critical (as
far as I am aware) is when taking multiple overlapping photos eg for a
panorama. I have seen special brackets with knurled knobs to move the
rotation point accurately to the position of the sensor if the camera's own
tripod bush isn't in the right place, though I'm not sure how you calibrate
it. It is probably important for movie cameras where the geometry has to
remain correct when panning during filming so a subject moving on a circular
path centred on the rotation point will remain in focus.

I agree that apart from this case, it makes sense to put the tripod point on
the lens (if it's a heavy lens) for better balance.

On Thursday, 1 October 2015 14:28:50 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
On Thursday, 1 October 2015 11:11:29 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
Ah! I didn't appreciate that your use of "DoF" wasn't referring to
depth
of
field,

thre are two DoFs in PHOTOGRAPHY. Nowerdays most people that do
photography know of depth of field, when I stared in the 6th form I
looked
DoF up in a photography book.

I'd never heard of depth of focus but a quick google has educated me on
that. Strictly speaking the "London Underground" sign marks the position
of
the film, rather than the range of positions of the film.
I think early cameras such as plate it was importan to make sure the plate
was in teh right place eraly cameras weren't acurratly made.


where the lens
would produce an acceptably sharp image, which I'm sure isn't a constant
and
varies according to focal length of lens.

I don;t think it does. if yuo have any camera with interchangable lens all
of tehm have to be in focus at the same point and that is where the film
or sensor is. In the old days yuo could take the film pack out and replace
it.
If teh fiml/sensor is in teh wrong place the picture will be out of focus.
Those with difital camera don;t consioder this and probley have never even
throught about it.

I doubt whether anyone with a camera with a fixed and defined focal plane
(eg the polished plate across which the film runs, with the 36x24 mm or
120-sized aperture in it) will have thought much about it.

I did in the mid 70s, I tried using it once to help me calculate
the magnification of a macro I was doing, as I was using bellows
this meant the usual film plane to rear objective was quite difernt from what you usually encounter. I;m betting Dennis will now claim I was trying to keep a afire alight because I was using bellows.

After all, the
position of the focal plane is no more adjustable for most film cameras than
for a digital camera.

It idsn;t really meant to be that mark is the FIXED location for measuring purposes.


Where the focal plane mark comes into its own is if you are setting focus of
your lens by tape measure rather than by adjusting the focus ring until the
correct part of the image is in focus on the focussing screen (or letting
the auto-focus do its job).

werent many auto-focus cameras back in the mid 70s of course.
As I've said I always thought of it as an aid in macro work.
I was also tiold it was useful when doing copyiong using a copying stand,
don;t see that sort of thing very often now.
If I need to copy documents I now use my ipad.
Have yet to find any DoF mark/indicator on that ;-)

How certain are you that "depth of focus mark" is the correct term for the
"underground symbol" mark?

only 99.48567892%

In camera manuals it's described as "focal
plane". Depth of focus (like depth of field) refers to a *range* of
distances - either side of the focal plane (in the case of depth of focus)



Yep as I said.

http://petapixel.com/2012/06/01/ever...-camera-means/

and it doesn;t move depending on teh lens either.

or either side of the subject (in the case of depth of field):
https://encrypted-tbn2.gstatic.com/i...My4vO0bTwyLldN

It is probably technically incorrect to refer to the "underground mark" as
"the depth of focus mark" (because this is a range rather than an absolute
distance) but nevertheless it may be that it is common parlance. If so, fair
enough, although all the references I've seen to the mark on cameras have
called it the focal plane mark.

which is the depth of focus, as that is where the point of focus of visible light will be at infinity IIRC.



Since the rigidity of the camera body keeps the lens perpendicular to the
sensor/film and the correct distance away, depth of focus isn't really an
issue for cameras unless you use bellows between lens and film.

yep well done.

Position of
focal plane is another matter and you'd use it for specialised focussing as
I described earlier.

Yes but what's specailed abouyt this focusing are you saying that you can't use the lens for focussing.



I doubt whether all lenses focus IR the same distance closer/further than
visible light. My gut feeling is that it may vary depending on the quality
of the lens (as well, almost certainly, on the focal length).

well yes a poor quality lens will give fringing of colour that's easily seen.

Here's why. A
simple lens made of a single piece of glass focuses different colours of
light at different distances, which results in chromatic aberration. To
counteract this, photographic and telescope lenses have elements made of a
combination of two pieces of glass of different refractive index to minimise
the difference. In general, the more you pay for a lens, the less chromatic
aberration you'll get - ie the smaller will be the depth of focus between
the red and violet ends of the spectrum.

so three is a term depth of focus YES
it is the term used when all visible light focuses on that point when teh light is parellel i.e focused at infinity, or a gants bollck away from infinity as you can never reach infinity can you.

Extending this further, a good lens
will correct over a wider range, extending to some part of the IR spectrum.
Mayeb but I'm not sure that will be a better quality lens.


It may not do it perfectly, but the degree to which it does governs how far
apart in depth the lens will focus visible and IR. For this reason, and the
fact that as you say a longer lens probably has a greater offset between IR
and visible focal planes, I'd expect it to make sense only to mark the two
focus points on the lens focussing scale and not on the camera.

yes and with large instumnents it might be easier moving teh focal plane than focusing think telescopes.


Effectively the underground mark is saying "this is where the sensor/film
is". A lens's focussing scale is marked such that a visible light image will
be focussed at the plane, by virtue of the camera having a fixed and
precisely controlled spacing between mount and film.

The vast majority of camera have that and I still haven;t seen teh undergropund mark on canerqas with fixed lenses so that give's me further evidence.

For IR, a different
lens-dependent offset is needed to counteract the fact that when the lens is
correctly focussed for visible light, IR will be focussed at a different
plane *whose position depends on the lens* both in terms of focal length and
degree of chromatic aberration correction.

so you could change the focal plane to rear objective distance as yuo do with telescopes and microscopes but rarley with photographic lenses .


How standard is it for the tripod mounting thread to be aligned with the
focal plane.

I'd say never but I've never seen one.

Can;t see the3 point of doing that the tripod mount should be so the
camera balancies better on the tripod and not stressing anyhting.
It's why you have tripod mounts on telephoto lenses and not normally on WA
ones.

The only time when the precise position of the tripod mount is critical (as
far as I am aware) is when taking multiple overlapping photos eg for a
panorama.

No don't agree there.

would yuo really mount this lens on yuor camera and use your camera tripod socket.
http://www.amazon.co.uk/650-2600mm-D... _SR160%2C160_

There's a reason why long lenese come with tripod sockets even my M3 to EOS converter as a tripod socket.

I have seen special brackets with knurled knobs

each to ther own. ;-)

to move the
rotation point accurately to the position of the sensor if the camera's own
tripod bush isn't in the right place,

what do you mean by isn;t in teh right place why would a camera maker not put the tripod mount not oin the right place ?

though I'm not sure how you calibrate
it. It is probably important for movie cameras where the geometry has to
remain correct when panning during filming so a subject moving on a circular
path centred on the rotation point will remain in focus.

there's special gimble and things for that.


I agree that apart from this case, it makes sense to put the tripod point on
the lens (if it's a heavy lens) for better balance.

I used to use a rifle grip arrangement.

"whisky-dave" wrote in message
...
How certain are you that "depth of focus mark" is the correct term for
the
"underground symbol" mark?

only 99.48567892%

In camera manuals it's described as "focal
plane". Depth of focus (like depth of field) refers to a *range* of
distances - either side of the focal plane (in the case of depth of
focus)



Yep as I said.

http://petapixel.com/2012/06/01/ever...-camera-means/

Actually that page describes the point as the focal plane or film plane mark
and doesn't use the term "depth of focus".


The only time when the precise position of the tripod mount is critical
(as
far as I am aware) is when taking multiple overlapping photos eg for a
panorama.

No don't agree there.

would yuo really mount this lens on yuor camera and use your camera tripod
socket.
http://www.amazon.co.uk/650-2600mm-D... _SR160%2C160_

There's a reason why long lenese come with tripod sockets even my M3 to
EOS converter as a tripod socket.

I agree that it would be horrendously out of balance. It's one hell of a
lens. I wouldn't like to hand-hold something 2.8 kg in weight and as long as
that - no smutty comments :-) And with a 2x converter - with a 5200 mm lens
you could probably almost have seen Neil Armstrong doing his "great leap"
;-) If 50 mm is regarded as 1:1 magnification then this thing is over 200x
magnification. Camera shake, thermal currents over long distances and
optical quality might be a problem.



I did say "precise" and I meant it as opposed to approximate. For balance
you mount a heavy lens as close to the centre of gravity of the lens+camera
unit, but the exact position isn't too critical.

Where it becomes critical, so I am told, is when taking several photographs
to join together. And then you'd mount the camera to rotate about its
sensor/film point. The two different uses wouldn't really come into conflict
as you are unlikely to use a 2600 mm lens to take separate images of a
panorama!


to move the
rotation point accurately to the position of the sensor if the camera's
own
tripod bush isn't in the right place,

what do you mean by isn;t in teh right place why would a camera maker not
put the tripod mount not oin the right place ?

As I said earlier it seems from a very quick sample of cameras I can lay my
hands on that DSLRs (and almost certainly film SLRs) do put the tripod mount
at that point (Nikon D90, Canon 10D), but compact cameras don't always
(Canon SX260). But that's a very limited sample. I can't find my older G9
compact to see where its mount is.

On Thursday, 1 October 2015 16:10:01 UTC+1, NY wrote:
"whisky-dave" wrote in message
...
How certain are you that "depth of focus mark" is the correct term for
the
"underground symbol" mark?

only 99.48567892%

In camera manuals it's described as "focal
plane". Depth of focus (like depth of field) refers to a *range* of
distances - either side of the focal plane (in the case of depth of
focus)



Yep as I said.

http://petapixel.com/2012/06/01/ever...-camera-means/

Actually that page describes the point as the focal plane or film plane mark
and doesn't use the term "depth of focus".


The only time when the precise position of the tripod mount is critical
(as
far as I am aware) is when taking multiple overlapping photos eg for a
panorama.

No don't agree there.

would yuo really mount this lens on yuor camera and use your camera tripod
socket.
http://www.amazon.co.uk/650-2600mm-D... _SR160%2C160_

There's a reason why long lenese come with tripod sockets even my M3 to
EOS converter as a tripod socket.

I agree that it would be horrendously out of balance. It's one hell of a
lens. I wouldn't like to hand-hold something 2.8 kg in weight and as long as
that - no smutty comments :-)

dam I had a long list of those :-)


And with a 2x converter - with a 5200 mm lens

I used a 400mm with a 2X and a 3X converter

you could probably almost have seen Neil Armstrong doing his "great leap"
;-) If 50 mm is regarded as 1:1 magnification.



then this thing is over 200x

I make it 104X with a FF sensor 166X with my EOS M3.
I'm thinking of buying one, but also considerign I:d be better off with a telescope.
I got some reasonable moon pics with my 70-300mm

magnification. Camera shake, thermal currents over long distances and
optical quality might be a problem.

yes that's why it's in a light colour too.


I did say "precise" and I meant it as opposed to approximate. For balance
you mount a heavy lens as close to the centre of gravity of the lens+camera
unit, but the exact position isn't too critical.

dependiong on the lens of course. I doubt many people even pros choose a camera based on where the tripod mount is.



Where it becomes critical, so I am told, is when taking several photographs
to join together. And then you'd mount the camera to rotate about its
sensor/film point. The two different uses wouldn't really come into conflict
as you are unlikely to use a 2600 mm lens to take separate images of a
panorama!

True and with modern software I don't think it's that importent.
I've done basic panos of 3 pics or so hand held.



to move the
rotation point accurately to the position of the sensor if the camera's
own
tripod bush isn't in the right place,

what do you mean by isn;t in teh right place why would a camera maker not
put the tripod mount not oin the right place ?

As I said earlier it seems from a very quick sample of cameras I can lay my
hands on that DSLRs (and almost certainly film SLRs) do put the tripod mount
at that point (Nikon D90, Canon 10D), but compact cameras don't always
(Canon SX260). But that's a very limited sample. I can't find my older G9
compact to see where its mount is.

pdreview might have the info too.
I have a canon G10