Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? Anyone?

Cheers
John

On 27/09/2010 22:46, Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? Anyone?

Cheers
John

Look at reflections on the surface of the lenses. If they are cloudy
you are in luck. Go to your local opticians or camera shop and get a
bottle of lens cleaner and a decent cloth, then polish. Gently.

If the reflections are shiny the dirt is inside. Find a _good_ camera
shop...

Andy.

Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? Anyone?


well if a wipe with optical cloth doesn't sort them, that's that.
Nothing to be done for less then buying decent ones.


I've found Russian kit to be a bit clunky, but optically good value for
money.


Cheers
John

On Mon, 27 Sep 2010 23:12:19 +0100, Andy Champ
wrote:

On 27/09/2010 22:46, Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? Anyone?

Cheers
John

Look at reflections on the surface of the lenses. If they are cloudy
you are in luck. Go to your local opticians or camera shop and get a
bottle of lens cleaner and a decent cloth, then polish. Gently.

If the reflections are shiny the dirt is inside. Find a _good_ camera
shop...

Or even a _good_ camera clinic - save on the commission charged by the
camera shop.
Agreed on the other recommendations.

Whatever you do, DON'T use Kleenex or similar paper tissues to clean
the lens faces. The wood fibre in the tissues WILL scratch any coating
on the lenses. Use microfibre cloth or even a clean cotton duster or a
bit of Terry towelling.

--
Frank Erskine

On Sep 28, 12:16*am, The Natural Philosopher
wrote:
Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". *I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? *Anyone?

well if a wipe with optical cloth doesn't sort them, that's that.
Nothing to be done for less then buying decent ones.

I've found Russian kit to be a bit clunky, but optically good value for
money.

Cheers
John



Watch for Lidl's regular binoculars appearing. Excellent value at
purely nominal price. Boat hirers here find them excellent, even in a
marine environment.

On Tue, 28 Sep 2010 00:20:51 +0100, Frank Erskine wrote:
On Mon, 27 Sep 2010 23:12:19 +0100, Andy Champ
wrote:

On 27/09/2010 22:46, Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? Anyone?

Cheers
John

Look at reflections on the surface of the lenses. If they are cloudy
you are in luck. Go to your local opticians or camera shop and get a
bottle of lens cleaner and a decent cloth, then polish. Gently.

If the reflections are shiny the dirt is inside. Find a _good_ camera
shop...

Or even a _good_ camera clinic - save on the commission charged by the
camera shop.
Agreed on the other recommendations.

Whatever you do, DON'T use Kleenex or similar paper tissues to clean
the lens faces. The wood fibre in the tissues WILL scratch any coating
on the lenses. Use microfibre cloth or even a clean cotton duster or a
bit of Terry towelling.

I regularly use kleenex, paper towels and even toilet tissue to
clean my binoculars and camera lenses. I've never had any hint
of scratches appearing on any optical surface. The only thing
you have to be careful about is that some tissues come impregnated
with balms or other goop that's supposed to make the user look
pretty - but just smears all over the lenses. (Maybe that's how it
works - for glasses wearers? :-) )

On a practical note, remove any large pieces of dirt or grit
that might be caked onto the lenses _before_ wiping with a
cleaner. Moving these around in contact with the glass will scratch
it. Even small dust-sized particles will abrade the surface and
will eventually lead to a dulling of the glass - no matter what
sort of cloth/paper you use to clean it. If there is grease on the
lens, a drop of washing up liquid very diluted in water and then
just enough to dampen a cloth will remove it.

Another source of "foggy" views is condensation inside the body
of the binoculars. You can either take them apart, which is a
bit drastic or leave them to dry out in a warm dry place (but not
a warm humid one) for a week or two.


--
http://www.thisreallyismyhost.99k.or...1728438206.php

On Tue, 28 Sep 2010 07:57:36 GMT, pete wrote:

Whatever you do, DON'T use Kleenex or similar paper tissues to
clean
the lens faces.

Cheap kitchen roll is OK, at least when I have cold that doesn't make
my nose sore like tissues do. I also use kitchen roll on my glasses
but that is really only for drying after the daily wash with
detergent (not soap it smears) and warm water.

Another source of "foggy" views is condensation inside the body
of the binoculars. You can either take them apart, which is a
bit drastic or leave them to dry out in a warm dry place (but not
a warm humid one) for a week or two.

Distinct possibilty and a problem for camera lenes as well. To avoid
the problem of internal fogging on the interior interview cameras at
sporting events they keep a spare lenes in the interview area and
swap the lens when the camera(s) come inside from being out in the
cold.

--
Cheers
Dave.

On 27 Sep, 22:46, Another John wrote:

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

If they're military, sell them untouched on eBay to a collector and
buy yourself a new pair. Makers like Ross, or the Naval spec 7×50s
always fetch a very good price.

Otherwise it's: Look, clean, dry, re-assemble.

If they're old, they're probably not coated (unless they're very high
quality), so coating breakdown won't be a problem. You might find that
they're simply mucky, in which case cleaning them externally is all
you need. This is best and by far the simplest. If they're damp
inside, if there's mould inside, or if the lens cement is failing then
you have to open the case to deal with it.

It's not practical to restore a coating. It's easy to do (you either
have a vacuum deposition machine, or you give money to those who do),
but we're talking big-budget restoration now.

External cleaning involves working wet and using a non-scratch cloth.
These used to be made of rag paper, but now they're made of
microfibres. You can get them free from the optician, or just buy a
clean microfibre duster. Don't use paper that isn't lens-cleaning
paper - wood fibre and dust is abrasive.

Work wet when cleaning them. Rinse carefully afterwards with soft
water, then dry somewhere warm and dry (top of a radiator conditions,
shielded from dust).

If they're decades old, then there's no reason not to open the case -
even if they're gas filled. They've probably been opened already
anyway. You will need appropriate tools though, as bodging with a
screwdriver is a great way to slip and damage a lens. Try one of the
online watch & optics suppliers for an adjustable lens ring / pin
spanner. I even saw them listed at Maplin.

When opening, watch out for fragile sealing rings. You'll probably
ruin these, if they're old. Replacement (in uk.d-i-y) can be done with
gasket compounds, but be careful not to smear them around! Best sort
is applied to one surface as a built-up ring, then left to dry before
assembly.

With the lenses removed, you can inspect both faces. Interior mould
cleans off fairly easily. An ultrasonic cleaner is useful, but be
careful as you can damage cemented lenses. You also need to ultrasonic
them in a trivet, so only the edges and not the faces are resting on
anything else.

Cemented lenses are where it gets awkward (and may fall apart if you
ultrasonic them). Breakdown of the cement or mould growth into balsam
cement is difficult to deal with. Your best bet (at sensible cost) is
to find an amateur telescope maker or university lab tech who makes
their own lenses and have them help you out in stripping the doublet
and re-cementing. Or just read up some lens grinding tech and go for
it yourself. It's a daft way to acquire binoculars, but I understand
the lure of the "project".

While they're apart, check and fix the mechanics. If the focus slides
or even just the hinges are worn, sort it out now.

To re-assemble, they should be inert gas filled. If they have a red
painted filling screw (military), they were certainly filled
originally. Fillings really ought to be dry nitrogen, but nitrogen,
carbon dioxide, or dried air are worth it. Easiest way is just a
squirt of photographer's inerting spray (used to be available fro
storing darkroom chemicals), or I use a squirt of argon from the MIG
welder cylinder. You're trying to displace moisture here (and ideally
oxygen), not to achieve a totally pure gas fill. Squirting enough of a
jet through a straw into the filler plug to flush out the casing, and
then re-inserting the plug quickly is perfectly adequate. You don't
need to assemble in a gas-filled glove box! It is worth doing at least
something here. Otherwise just re-assemble in an atmosphere of dry,
cool air (chuck it in a sealed plastic box for a few hours, along with
a couple of big, fresh silica gel bags). Don't use warm dry air, as
relative humidity will bite you in the future. That warm air has a low
RH but might have still quite a high absolute humidity. When it goes
cold, you still see condensation.

Another trick that's worth it (if there's a suitable space alongside a
prism) is to assemble them with a small silica gel dessicator inside
the case. Wedge, tie, or superglue this in place. Remember to re-
activate the gel before use and don't have it contacting an internally
reflective face of the prism (stick it at the side) or it can appear
as a ghost. Don't put adhesives on the optics either. In fact don't
use superglue - it's handy, but remember CSI and the vapour's use for
revealing fingerprints! Use it in an empty casing, but don't have the
optics in the room at the time.


To be honest, a new pair from Lidl will probably be better quality and
lighter. Modern design and manufacturing has really changed optics at
this level.

Another make worth looking at is Luger. I bought a pair of their cheap
compacts recently (8×25, £25-ish) and they're one of the best and
brightest pairs of binoculars I have.

On 28 Sep, 00:49, John MacLeod wrote:

Watch for Lidl's regular binoculars appearing. * Excellent value at
purely nominal price. *

Lidl's are odd. Their "mainstream" binoculars are as you say, cheap
and excellent. Quite light too. These are the ones I use most for
planned trips, as I can throw them around and leave them in the car.
Likewise Aldi's spotting scopes for under 30 quid.

Their "boat" binoculars though are expensive, especially those with
the built-in bearing compass. A look at eBay or Chinese sites shows
the same thing for less.

Their compact binoculars are, like most cheap compacts, poor quality
with dull images and narrow view angles.

"Andy Dingley" wrote in message
...
On 28 Sep, 00:49, John MacLeod wrote:

Watch for Lidl's regular binoculars appearing. Excellent value at
purely nominal price.

Lidl's are odd. Their "mainstream" binoculars are as you say, cheap
and excellent. Quite light too. These are the ones I use most for
planned trips, as I can throw them around and leave them in the car.
Likewise Aldi's spotting scopes for under 30 quid.

Their "boat" binoculars though are expensive, especially those with
the built-in bearing compass. A look at eBay or Chinese sites shows
the same thing for less.

Their compact binoculars are, like most cheap compacts, poor quality
with dull images and narrow view angles.



By narrow view angle - do you mean they give a telescopic image? surely the
greater the magnification the narrower the angle.

On 27 Sep, 22:46, Another John wrote:
Howdy all

I just bought some second-hand binoculars -- cheap, because they're
old-school 10x50s, and weigh about a Kg.

They're great for what I want, but the image seems a little "foggy". *I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

Is there any way to clean them up and make the image clearer? *Anyone?

Cheers
John

Further to the above, you can get fungus growing inside them. The only
solution then is dismantling. I have tried this for myself in the
past. It's usually been a failed operation :-)

On 28/09/2010 10:09, John wrote:


By narrow view angle - do you mean they give a telescopic image? surely the
greater the magnification the narrower the angle.



Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy

"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:


By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.



Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means a
narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm lens
had a field of view of about 90degrees)

"John" wrote in message
...
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:


By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.



Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means
a narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm
lens had a field of view of about 90degrees)



Sorry to labour this but if for example I want to see a distant object and
have it fill my field of vision then the angle of view from the lens has to
be very small (eg a ship in the distance) If the angle of view is wider then
I will see more than the ship and therefore the ship isn't occupying the
whole of my field of view (ie - not as magnified)

"Andy Dingley" wrote in message
...
On 27 Sep, 22:46, Another John wrote:

They're great for what I want, but the image seems a little "foggy". I
don't know if this is due to the lens coatings deteriorating, or if dirt
has somehow got into the assembly (unlikely, it seems to me).

If they're military, sell them untouched on eBay to a collector and
buy yourself a new pair. Makers like Ross, or the Naval spec 7×50s
always fetch a very good price.

Otherwise it's: Look, clean, dry, re-assemble.

If they're old, they're probably not coated (unless they're very high
quality), so coating breakdown won't be a problem. You might find that
they're simply mucky, in which case cleaning them externally is all
you need. This is best and by far the simplest. If they're damp
inside, if there's mould inside, or if the lens cement is failing then
you have to open the case to deal with it.

It's not practical to restore a coating. It's easy to do (you either
have a vacuum deposition machine, or you give money to those who do),
but we're talking big-budget restoration now.

External cleaning involves working wet and using a non-scratch cloth.
These used to be made of rag paper, but now they're made of
microfibres. You can get them free from the optician, or just buy a
clean microfibre duster. Don't use paper that isn't lens-cleaning
paper - wood fibre and dust is abrasive.

Work wet when cleaning them. Rinse carefully afterwards with soft
water, then dry somewhere warm and dry (top of a radiator conditions,
shielded from dust).

If they're decades old, then there's no reason not to open the case -
even if they're gas filled. They've probably been opened already
anyway. You will need appropriate tools though, as bodging with a
screwdriver is a great way to slip and damage a lens. Try one of the
online watch & optics suppliers for an adjustable lens ring / pin
spanner. I even saw them listed at Maplin.

When opening, watch out for fragile sealing rings. You'll probably
ruin these, if they're old. Replacement (in uk.d-i-y) can be done with
gasket compounds, but be careful not to smear them around! Best sort
is applied to one surface as a built-up ring, then left to dry before
assembly.

With the lenses removed, you can inspect both faces. Interior mould
cleans off fairly easily. An ultrasonic cleaner is useful, but be
careful as you can damage cemented lenses. You also need to ultrasonic
them in a trivet, so only the edges and not the faces are resting on
anything else.

Cemented lenses are where it gets awkward (and may fall apart if you
ultrasonic them). Breakdown of the cement or mould growth into balsam
cement is difficult to deal with. Your best bet (at sensible cost) is
to find an amateur telescope maker or university lab tech who makes
their own lenses and have them help you out in stripping the doublet
and re-cementing. Or just read up some lens grinding tech and go for
it yourself. It's a daft way to acquire binoculars, but I understand
the lure of the "project".

While they're apart, check and fix the mechanics. If the focus slides
or even just the hinges are worn, sort it out now.

To re-assemble, they should be inert gas filled. If they have a red
painted filling screw (military), they were certainly filled
originally. Fillings really ought to be dry nitrogen, but nitrogen,
carbon dioxide, or dried air are worth it. Easiest way is just a
squirt of photographer's inerting spray (used to be available fro
storing darkroom chemicals), or I use a squirt of argon from the MIG
welder cylinder. You're trying to displace moisture here (and ideally
oxygen), not to achieve a totally pure gas fill. Squirting enough of a
jet through a straw into the filler plug to flush out the casing, and
then re-inserting the plug quickly is perfectly adequate. You don't
need to assemble in a gas-filled glove box! It is worth doing at least
something here. Otherwise just re-assemble in an atmosphere of dry,
cool air (chuck it in a sealed plastic box for a few hours, along with
a couple of big, fresh silica gel bags). Don't use warm dry air, as
relative humidity will bite you in the future. That warm air has a low
RH but might have still quite a high absolute humidity. When it goes
cold, you still see condensation.

Another trick that's worth it (if there's a suitable space alongside a
prism) is to assemble them with a small silica gel dessicator inside
the case. Wedge, tie, or superglue this in place. Remember to re-
activate the gel before use and don't have it contacting an internally
reflective face of the prism (stick it at the side) or it can appear
as a ghost. Don't put adhesives on the optics either. In fact don't
use superglue - it's handy, but remember CSI and the vapour's use for
revealing fingerprints! Use it in an empty casing, but don't have the
optics in the room at the time.


To be honest, a new pair from Lidl will probably be better quality and
lighter. Modern design and manufacturing has really changed optics at
this level.

Another make worth looking at is Luger. I bought a pair of their cheap
compacts recently (8×25, £25-ish) and they're one of the best and
brightest pairs of binoculars I have.

That's an interesting account thanks Andy.

I once asked about how compound lenses are stuck together, on the Wikipedia
pages about lenses. I have an old, but much loved. pair that had like a
gold iris effect on one side. I've cleaned and realigned both barrels, and
the optics quite nicely, but I never had the nerve to try tackling the 'gold
iris effect', which is where the two parts of a compound lens are presumably
suffering from the balsam that holds them together drying out and
crystallising from the edge.

I did wonder if soaking the lens in xylene might gradually swell the dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

Cheers,

S

John wrote:
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:

By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.


Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means a
narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm lens
had a field of view of about 90degrees)


that is with a fixed negative size. Now google vignetting

"The Natural Philosopher" wrote in message
...
John wrote:
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:

By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.


Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means
a narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm
lens had a field of view of about 90degrees)
that is with a fixed negative size. Now google vignetting


I am familiar with it. So what Andy Champ meant was a "clearer view across
the whole of the narrow field of view"

On Tue, 28 Sep 2010 21:14:57 +0100, John wrote:
"John" wrote in message
...
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:


By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.



Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means
a narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm
lens had a field of view of about 90degrees)



Sorry to labour this but if for example I want to see a distant object and
have it fill my field of vision then the angle of view from the lens has to
be very small (eg a ship in the distance) If the angle of view is wider then
I will see more than the ship and therefore the ship isn't occupying the
whole of my field of view (ie - not as magnified)

Better (i.e. more expensive) eyepieces in binoculars and telescopes
give you a larger image than cheap eyepieces. So when you look at
something through cheapo binoculars, you might see (say) a house in
the distance and it'll be surrounded by the black circular "frame"
in which the rest of the vista is cut off from sight. With better
equipment that has a higher _apparent_ field of view, that black
circle is larger, although the magnification will be the same (so the
house is the same size in both pairs of binoculars). The
result is that you see not just the house but the things around it,
too. That's assuming the same focal length binoculars and the same
magnification eyepieces. You just see more stuff in the view.

--
http://www.thisreallyismyhost.99k.or...7410913609.php

John wrote:
"The Natural Philosopher" wrote in message
...
John wrote:
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:
By narrow view angle - do you mean they give a telescopic image? surely
the
greater the magnification the narrower the angle.


Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy

Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power means
a narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm
lens had a field of view of about 90degrees)
that is with a fixed negative size. Now google vignetting


I am familiar with it. So what Andy Champ meant was a "clearer view across
the whole of the narrow field of view"


No, its more total angle of view. I.e vignetting down to complete
dark..The eye has about 135 deg. angle over which it can see things. So
at a 10x magnification you would hope for the same angle of illumination
behind the glasses, and 13 degrees total distant coverage. You get
nothing like that.

In the limit the angle is dictated by the primary lens diameter and its
focal length and then by the power of the eyepiece lens. I've forgotten
all the maths. But more glass is better IIRC :-)

The retina is always far larger than the area that is illuminated by the
glasses.

So the field of view is actually small and circular. Good glasses have
a much wider field of view. That's why they are more useful than either
a telescope or a telephoto lens.

"pete" wrote in message
...
On Tue, 28 Sep 2010 21:14:57 +0100, John wrote:
"John" wrote in message
...
"Andy Champ" wrote in message
. uk...
On 28/09/2010 10:09, John wrote:


By narrow view angle - do you mean they give a telescopic image?
surely
the
greater the magnification the narrower the angle.



Good binoculars will give a wider field of view than cheap ones at the
same magnification.

Andy


Doesn't magnification equate to a narrower area of view?

My background is in photography and the greater the telephoto power
means
a narrower angle of view. Isn't it the same? (a 35mm camera standard
50mm
lens had a field of view of about 90degrees)



Sorry to labour this but if for example I want to see a distant object
and
have it fill my field of vision then the angle of view from the lens has
to
be very small (eg a ship in the distance) If the angle of view is wider
then
I will see more than the ship and therefore the ship isn't occupying the
whole of my field of view (ie - not as magnified)

Better (i.e. more expensive) eyepieces in binoculars and telescopes
give you a larger image than cheap eyepieces. So when you look at
something through cheapo binoculars, you might see (say) a house in
the distance and it'll be surrounded by the black circular "frame"
in which the rest of the vista is cut off from sight. With better
equipment that has a higher _apparent_ field of view, that black
circle is larger, although the magnification will be the same (so the
house is the same size in both pairs of binoculars). The
result is that you see not just the house but the things around it,
too. That's assuming the same focal length binoculars and the same
magnification eyepieces. You just see more stuff in the view.

--
http://www.thisreallyismyhost.99k.or...7410913609.php


Thanks

On 28 Sep, 21:44, "Spamlet" wrote:
I did wonder if soaking the lens in xylene might gradually swell the dried
balsam back into a more see through condition. *If not, how does one
separate the elements and what are they stuck together with these days?

I think balsam was still used into the '80s, but the quality did vary
between makers (late WW2 German ersatz stuff is supposed to be
particularly iffy) and its fairly easy to work with.

You strip them down with heat, I would suggest using a waterbath on a
hotplate at a bit below boiling point. Go easy on speed of raising the
temperature though. LET THEM FALL APART AND DO NOT PRY AT THEM! Clean
up once apart with acetone (or I guess xylene too).

Re-assemble with canada balsam, which is available and easy to work
with. Your big problem here is centring the lenses, and the difficulty
of that depends on how accurately their edges were ground, relative to
the optical centre. If that's accurate, you can align them
mechanically with a few accurate blocks on a surface plate (and
remember that optical benches are stable, but far from flat). Best
alignment is done with some sort of laser interferometer and doing it
optically, but its years since I dealt with that level of geekery.

If they're synthetically bonded rather than with balsam, it's really
not worth bothering. However if you do, it's a long soak (and I mean
days upwards) is a solvent like xylene or most likely MEK. I've never
done this myself, and I think the success rate isn't encouraging.

"Andy Dingley" wrote in message
...
On 28 Sep, 21:44, "Spamlet" wrote:
I did wonder if soaking the lens in xylene might gradually swell the
dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

I think balsam was still used into the '80s, but the quality did vary
between makers (late WW2 German ersatz stuff is supposed to be
particularly iffy) and its fairly easy to work with.

You strip them down with heat, I would suggest using a waterbath on a
hotplate at a bit below boiling point. Go easy on speed of raising the
temperature though. LET THEM FALL APART AND DO NOT PRY AT THEM! Clean
up once apart with acetone (or I guess xylene too).

Re-assemble with canada balsam, which is available and easy to work
with. Your big problem here is centring the lenses, and the difficulty
of that depends on how accurately their edges were ground, relative to
the optical centre. If that's accurate, you can align them
mechanically with a few accurate blocks on a surface plate (and
remember that optical benches are stable, but far from flat). Best
alignment is done with some sort of laser interferometer and doing it
optically, but its years since I dealt with that level of geekery.

If they're synthetically bonded rather than with balsam, it's really
not worth bothering. However if you do, it's a long soak (and I mean
days upwards) is a solvent like xylene or most likely MEK. I've never
done this myself, and I think the success rate isn't encouraging.

Has anyone recommending dismantling binoculars ever done it?
They are extremely difficult to collimate especially to more than one
person.
Its bad enough doing one set of lens let alone two on the same axis.

"Andy Dingley" wrote in message
...
On 28 Sep, 21:44, "Spamlet" wrote:
I did wonder if soaking the lens in xylene might gradually swell the
dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

I think balsam was still used into the '80s, but the quality did vary
between makers (late WW2 German ersatz stuff is supposed to be
particularly iffy) and its fairly easy to work with.

You strip them down with heat, I would suggest using a waterbath on a
hotplate at a bit below boiling point. Go easy on speed of raising the
temperature though. LET THEM FALL APART AND DO NOT PRY AT THEM! Clean
up once apart with acetone (or I guess xylene too).

Re-assemble with canada balsam, which is available and easy to work
with. Your big problem here is centring the lenses, and the difficulty
of that depends on how accurately their edges were ground, relative to
the optical centre. If that's accurate, you can align them
mechanically with a few accurate blocks on a surface plate (and
remember that optical benches are stable, but far from flat). Best
alignment is done with some sort of laser interferometer and doing it
optically, but its years since I dealt with that level of geekery.

If they're synthetically bonded rather than with balsam, it's really
not worth bothering. However if you do, it's a long soak (and I mean
days upwards) is a solvent like xylene or most likely MEK. I've never
done this myself, and I think the success rate isn't encouraging.

Has anyone recommending dismantling binoculars ever done it?
They are extremely difficult to collimate especially to more than one
person.
Its bad enough doing one set of lens let alone two on the same axis.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Spamlet"
saying something like:

I once asked about how compound lenses are stuck together, on the Wikipedia
pages about lenses. I have an old, but much loved. pair that had like a
gold iris effect on one side. I've cleaned and realigned both barrels, and
the optics quite nicely, but I never had the nerve to try tackling the 'gold
iris effect', which is where the two parts of a compound lens are presumably
suffering from the balsam that holds them together drying out and
crystallising from the edge.

I did wonder if soaking the lens in xylene might gradually swell the dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

You can seperate balsam-glued lenses and reglue them back with fresh
balsam. You can make a jig to hold them in registration, with a due
degree of care and attention to detail. Whatever you do, don't try this
on a valuable lens as a first attempt; indeed, pick up a scrap lens for
practice.
You could also use modern glue, but it's very much a fit and never take
apart exercise. Balsam has the saving grace (age though it might) of
being re-doable.

"Grimly Curmudgeon" wrote in message
...
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Spamlet"
saying something like:

I once asked about how compound lenses are stuck together, on the
Wikipedia
pages about lenses. I have an old, but much loved. pair that had like a
gold iris effect on one side. I've cleaned and realigned both barrels,
and
the optics quite nicely, but I never had the nerve to try tackling the
'gold
iris effect', which is where the two parts of a compound lens are
presumably
suffering from the balsam that holds them together drying out and
crystallising from the edge.

I did wonder if soaking the lens in xylene might gradually swell the dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

You can seperate balsam-glued lenses and reglue them back with fresh
balsam. You can make a jig to hold them in registration, with a due
degree of care and attention to detail. Whatever you do, don't try this
on a valuable lens as a first attempt; indeed, pick up a scrap lens for
practice.
You could also use modern glue, but it's very much a fit and never take
apart exercise. Balsam has the saving grace (age though it might) of
being re-doable.

Thanks to all for more background,

I used to do refractive index measurement as part of mineral identification
in studying geology. The trick was to find a liquid that had the same RI as
the mineral and would therefore make it's outline 'disappear'. Some, or
most, minerals being birefringent or more, it was always a bit of a hit and
miss affair with much depending on the mineral/crystal's alignment.
However, coming to the point, I thought balsam was chosen for it's RI being
close to that of the glasses used in the lens, so that it did not interfere
with the optical properties very much. (My lens developing it's gold corona
as the balsam deteriorates, demonstrating the point.) The lens in question
is part of one optic and its alignment should not be that critical so long
as I can get the right thickness/RI and 'bubblefreeness' of the cementing
medium.

I don't know whether this is a 'good' pair of binoculars or not, but they
are old and well worn: not as powerful and compact as modern 'in line'
types, but much easier to bring on target quickly. As with all such items,
someone will drop them sooner or later - Dennis - so it is as well to learn
how to clean and realign the barrels at least. These particular ones were
tending to rise to one side on the finger screw so did need to be
disassembled to clean and grease to get them all rising smoothly. In this
old type, the alignment of the optics was done by eccentric rings held in
place by a lot of a thick waxy substance. Once one realised the purpose of
the offset rings it was just a case of 'tweak and peek' to gradually get
both sides aligned with a point at infinity: a distant branch or chimney pot
will do. Fiddly, but quite doable.

Once I'd done this on the old pair I had a go at a newer pair which had been
well dropped and were several degrees out of alignment. These had long been
given up for dead, but I found this type actually had centring screws, and
were surprisingly easy to gradually tweak back into alignment. I was very
pleased with the result as they turned out to be brighter and sharper than
my general purpose - in the pocket all the time, modern inline prism pair.

As a schoolkid, I recall, the main interest kids had in binoculars was in
taking them apart to play with the prisms, so I suppose, anyone in my cohort
of kids, would not be put off by trying these things for ourselves.
Obviously, if it is high definition astronomy you are into, then the fancy
equipment comes in to play, but for general purposes one can normally find a
compromise - like that distant chimney, in place of an optical bench, for
example. (Actually, my school physics recalls such contraptions as being a
pain in the neck to use. Though I did very much like the 'universal stage'
I got to use later in my mineral crystal tests.)

Fiddliest binocular (and digital camera) stripdown/clean, came after I
stepped onto what turned out to be a deep layer of fine silt in a stream
bed. This was so fine that it got into my camera and even inside the
supposedly waterproof rubber coated inline prism binocs! Took me quite a
bit of head scratching to work out how the modern binocs worked and came
apart, but once I had discovered the functions of the various screws, it
wasn't that difficult. Again, the most fiddly thing was getting both sides
to slide together as one turns the finger screw. I still have to give one
side a bit of a tug to be able to make full use of the eye adjustment, but I
can live with that.

Cheers,

S

"Spamlet" wrote in message
...

"Grimly Curmudgeon" wrote in message
...
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Spamlet"
saying something like:

I once asked about how compound lenses are stuck together, on the
Wikipedia
pages about lenses. I have an old, but much loved. pair that had like a
gold iris effect on one side. I've cleaned and realigned both barrels,
and
the optics quite nicely, but I never had the nerve to try tackling the
'gold
iris effect', which is where the two parts of a compound lens are
presumably
suffering from the balsam that holds them together drying out and
crystallising from the edge.

I did wonder if soaking the lens in xylene might gradually swell the
dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

You can seperate balsam-glued lenses and reglue them back with fresh
balsam. You can make a jig to hold them in registration, with a due
degree of care and attention to detail. Whatever you do, don't try this
on a valuable lens as a first attempt; indeed, pick up a scrap lens for
practice.
You could also use modern glue, but it's very much a fit and never take
apart exercise. Balsam has the saving grace (age though it might) of
being re-doable.

Thanks to all for more background,

I used to do refractive index measurement as part of mineral
identification in studying geology. The trick was to find a liquid that
had the same RI as the mineral and would therefore make it's outline
'disappear'. Some, or most, minerals being birefringent or more, it was
always a bit of a hit and miss affair with much depending on the
mineral/crystal's alignment. However, coming to the point, I thought
balsam was chosen for it's RI being close to that of the glasses used in
the lens, so that it did not interfere with the optical properties very
much. (My lens developing it's gold corona as the balsam deteriorates,
demonstrating the point.) The lens in question is part of one optic and
its alignment should not be that critical so long as I can get the right
thickness/RI and 'bubblefreeness' of the cementing medium.

I don't know whether this is a 'good' pair of binoculars or not, but they
are old and well worn: not as powerful and compact as modern 'in line'
types, but much easier to bring on target quickly. As with all such
items, someone will drop them sooner or later - Dennis - so it is as well
to learn how to clean and realign the barrels at least. These particular
ones were tending to rise to one side on the finger screw so did need to
be disassembled to clean and grease to get them all rising smoothly. In
this old type, the alignment of the optics was done by eccentric rings
held in place by a lot of a thick waxy substance. Once one realised the
purpose of the offset rings it was just a case of 'tweak and peek' to
gradually get both sides aligned with a point at infinity: a distant
branch or chimney pot will do. Fiddly, but quite doable.

Once I'd done this on the old pair I had a go at a newer pair which had
been well dropped and were several degrees out of alignment. These had
long been given up for dead, but I found this type actually had centring
screws, and were surprisingly easy to gradually tweak back into alignment.
I was very pleased with the result as they turned out to be brighter and
sharper than my general purpose - in the pocket all the time, modern
inline prism pair.

As a schoolkid, I recall, the main interest kids had in binoculars was in
taking them apart to play with the prisms, so I suppose, anyone in my
cohort of kids, would not be put off by trying these things for ourselves.
Obviously, if it is high definition astronomy you are into, then the fancy
equipment comes in to play, but for general purposes one can normally find
a compromise - like that distant chimney, in place of an optical bench,
for example. (Actually, my school physics recalls such contraptions as
being a pain in the neck to use. Though I did very much like the
'universal stage' I got to use later in my mineral crystal tests.)

Fiddliest binocular (and digital camera) stripdown/clean, came after I
stepped onto what turned out to be a deep layer of fine silt in a stream
bed. This was so fine that it got into my camera and even inside the
supposedly waterproof rubber coated inline prism binocs! Took me quite a
bit of head scratching to work out how the modern binocs worked and came
apart, but once I had discovered the functions of the various screws, it
wasn't that difficult. Again, the most fiddly thing was getting both
sides to slide together as one turns the finger screw. I still have to
give one side a bit of a tug to be able to make full use of the eye
adjustment, but I can live with that.


[Here's a link to the Wikipedia discussion had on the topic back in 2007: I
never did get around to hunting for the materials at the time, but I notice
a few more details have been added since my last look:
http://en.wikipedia.org/wiki/Talk:Achromatic_lens ]

Cheers,

S

On 28/09/2010 22:18, pete wrote:
Better (i.e. more expensive) eyepieces in binoculars and telescopes
give you a larger image than cheap eyepieces. So when you look at
something through cheapo binoculars, you might see (say) a house in
the distance and it'll be surrounded by the black circular "frame"
in which the rest of the vista is cut off from sight. With better
equipment that has a higher _apparent_ field of view, that black
circle is larger, although the magnification will be the same (so the
house is the same size in both pairs of binoculars). The
result is that you see not just the house but the things around it,
too. That's assuming the same focal length binoculars and the same
magnification eyepieces. You just see more stuff in the view.


Beautifully put, saves me the trouble of elaborating!

Andy

On 29 Sep, 11:01, "dennis@home" wrote:

Has anyone recommending dismantling binoculars ever done it?

I haven't seen anyone recommending it. However if you have to, you
have to.

They are extremely difficult to collimate especially to more than one
person.

No, they're a piece of ****. They're designed for easy mass production
and they're not particularly sensitive to mis-alignment anyway. 10×
magnification? It's hardly rocket surgery.

Apart from, I think, a huge pair of East German border guard jobbies,
I've not seen any binoculars that were adjustable to collimate anyway.
The lenses are centred, and the rest is down to trusting the lens
mounts to be machined accurately. Re-assembly is just the reverse of
dismantling.

Besides which, what does "collimate to more than one person." mean?
Collimation is collimation, it doesn't vary between people. Even for
your pointy little head.

"Andy Dingley" wrote in message
...
On 29 Sep, 11:01, "dennis@home" wrote:

Has anyone recommending dismantling binoculars ever done it?

I haven't seen anyone recommending it. However if you have to, you
have to.

They are extremely difficult to collimate especially to more than one
person.

No, they're a piece of ****. They're designed for easy mass production
and they're not particularly sensitive to mis-alignment anyway. 10×
magnification? It's hardly rocket surgery.

Apart from, I think, a huge pair of East German border guard jobbies,
I've not seen any binoculars that were adjustable to collimate anyway.
The lenses are centred, and the rest is down to trusting the lens
mounts to be machined accurately. Re-assembly is just the reverse of
dismantling.

Besides which, what does "collimate to more than one person." mean?
Collimation is collimation, it doesn't vary between people. Even for
your pointy little head.

Lidl binos can be collimated, they have various adjustments.
Most are the same, you just don't have a clue what to look for or what it
means.

Google for conditional collimation and you might learn something to fit in
you flat, empty head.

On 30 Sep, 09:50, "dennis@home" wrote:

Google for conditional collimation and you might learn something to fit in
you flat, empty head.

FFS! So that's where all the hi-fi nutters went.

"Conditional collimation" is nothing of the sort, nor is mutual
collimation. It's _alignment_ (and important, I'll grant) rather than
collimation. A chorus of screaming ****wits doesn't make it so.

Collimation is the alignment of an optical system, such that
everything with an axis that cares about it is aligned to the same
mutual axis. Often (but not always) this is for the purpose of
producing collimated (i.e. parallel beam) light. This isn't always
needed, as not all systems are trying to achieve such light, but you
won't achieve the second without the first. "Alignment" also means
both angular and sideways displacement (although plane elements don't
care about sideways shift).

In binocular terms, there are two optical systems and they don't
interact (outside of nerves in your head). Each system is thus
collimated separately. There is no mutual collimation, no conditional
collimation. Collimation is also objective - the system has an ideal
collimation (which in most cases is just "everything straight down the
middle" and there's no "tuning" of this to a subjective use, i.e. the
best collimation is the best collimation, there's no "setting it up
for Fred".

There's one case where this doesn't apply - spectacles. That system is
quite crucially your eyeball and the spectacle lens, collimation being
dependent upon the frame and even the nosepads. This is why an
optician who gives a damn about measuring IPD (interpupillary
distance) is so important and why you shouldn't go to Specsavers.

Collimation is achieved in most optical systems by making accurate
components and putting them into accurate lens holders. If the optical
centre of a lens is in its geometric centre, and the lens holders are
accurately made in the lens tube, then it all just works out fine.
This has several benefits - fiirstly it's obviously cheaper (than
adjustable lens mounts), secondly its better (the accuracy of doing it
this way in modern production achieves better than most adjustment
processes will), thirdly (and most importantly) it's more robust:
binoculars get dropped.

Collimation obviously goes to lunch when you dismantle binoculars, so
getting them back together afterwards is indeed an issue. Hopefully
though (and this is true for everything small and cheap) it's a re-
assembly task onto static marks. As discussed, binoculars avoid
collimation adjustments for the sake of robustness. If you have any,
the first place they'll appear is around the prism. This is because
prisms aren't as easy to self-align as a simple Gallilean telescope
tube. Even then, you're not going to see adjustments here unless
you're dealing with three things simultaneously: high quality, high
magnification, fixed mount. "Field" binoculars avoid adjustments.

On 30 Sep, 11:34, Andy Dingley wrote:

"Conditional collimation" is nothing of the sort, nor is mutual
collimation. It's _alignment_ (and important, I'll grant) rather than
collimation.

Alignment is important, as the suggested web sources point out (the
Oberwerk videos are pretty good). However this alignment is about the
"fit" of the binoculars to the user's eyes and, in the extreme cases,
about the relative alignment of the two halves of the binocular. This
isn't collimation though.

Once again, field binoculars avoid this stuff where they can, because
they're better off with robustness than with factory perfection.

The best "adjustment" for alignment is in the brain. We're good at
this. If the binoculars are low magnification, you can stare at any
old rubbish and the brain sorts it out. It starts to be more important
though if any of the following apply: high magnification, dark
images, long times staring through them, fast moving targets,
particularly for acquisition of new images with tiny targets. I've
just had a look at my collection and the only binoculars with a really
comprehensive alignment system are a pair of ex-RN fixed mount ones
that are quite low mag (about 7×) and came off the optical tracker
pedestal from a Seacat missile launcher - Fast moving acquisition.

Alignment here is mostly around setting the IPD right, which you have
to do each time you get them out of the case (and why I always carry
my own pair, because my own sight is asymmetric, a bit crap, and a
pain to adjust for). User handling at the time of viewing is still the
biggest deal in getting a good image, not faffing about over minutiae.
If you're using high magnification or staring for ages, you also need
to align the axes carefully. This is usually done (if possible) by
looking for adjustment setscrews between the lens housing arrangements
(a pre-collimated tube that we don't mess with) and the hinged frame
of the binoculars. They're sometimes hidden under the rubber grip.
Then follow Mr Oberwerk, who explains it pretty well. He also refers
to it as "Alignment (collimation)" throughout his vid.

"Andy Dingley" wrote in message
...

Collimation obviously goes to lunch when you dismantle binoculars, so
getting them back together afterwards is indeed an issue. Hopefully
though (and this is true for everything small and cheap) it's a re-
assembly task onto static marks. As discussed, binoculars avoid
collimation adjustments for the sake of robustness. If you have any,
the first place they'll appear is around the prism. This is because
prisms aren't as easy to self-align as a simple Gallilean telescope
tube.


What have opera glasses got to do with binos? Why introduce them here? You
do know that a Galilean telescope doesn't use optics the same as a set of
binoculars? Except maybe a few "focus" free models and opera glasses.

Even then, you're not going to see adjustments here unless
you're dealing with three things simultaneously: high quality, high
magnification, fixed mount. "Field" binoculars avoid adjustments.

As I said you just don't know where to look.
I will give you a hint, they are aligned in the factory by hand which is why
Chinese stuff is cheaper, the hands cost less.
If you look you may even find some alignment marks on the lenses put there
so they could be assembled after testing.
Of course they only allow for alignment in one axis.

"Andy Dingley" wrote in message
...
On 29 Sep, 11:01, "dennis@home" wrote:

Has anyone recommending dismantling binoculars ever done it?

I haven't seen anyone recommending it. However if you have to, you
have to.

They are extremely difficult to collimate especially to more than one
person.

No, they're a piece of ****. They're designed for easy mass production
and they're not particularly sensitive to mis-alignment anyway. 10×
magnification? It's hardly rocket surgery.

Apart from, I think, a huge pair of East German border guard jobbies,
I've not seen any binoculars that were adjustable to collimate anyway.
The lenses are centred, and the rest is down to trusting the lens
mounts to be machined accurately. Re-assembly is just the reverse of
dismantling.

Besides which, what does "collimate to more than one person." mean?
Collimation is collimation, it doesn't vary between people. Even for
your pointy little head.

Not sure what is meant by collimation here (usually associate this with
microscope light sources), but, without my glasses on I do find there is not
enough adjustment on one of the eyepieces to correct for the difference in
my eyes: so maybe that is what is meant. I can usually find a way to tweak
the length of one ocular a little though.

S