Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye make-up
because she can't reach her eyes with the glasses on and can't see her
reflection with them off.

She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I know that if she uses a 3 dipotre magnifying glass on a plain mirror,
she can see OK, but the problem is that a mirror will be labelled as 3X
or 5X, whereas a lens gets categorised by dioptres or focal length.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

Roly wrote:
Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye
make-up because she can't reach her eyes with the glasses on and
can't see her reflection with them off.

She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I know that if she uses a 3 dipotre magnifying glass on a plain
mirror, she can see OK, but the problem is that a mirror will be
labelled as 3X or 5X, whereas a lens gets categorised by dioptres or
focal length.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

She'd be better off with contact lenses.

--
Sir Benjamin Middlethwaite

The3rd Earl Of Derby wrote:

Roly wrote:
Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye
make-up because she can't reach her eyes with the glasses on and
can't see her reflection with them off.

She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I know that if she uses a 3 dipotre magnifying glass on a plain
mirror, she can see OK, but the problem is that a mirror will be
labelled as 3X or 5X, whereas a lens gets categorised by dioptres or
focal length.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

She'd be better off with contact lenses.

She's tried contacts but can't get on with them.

She's also tried glasses where each lens individually flips down and
she's tried a monacle too.

Each of those solutions causes further problems for her, but the mirror
& magnifying glass solution has worked well for more than ten years.
However it's inconvenient to hold it all together, so a stronger
magnifying mirror appears to be the ideal answer.

Boots do a Tweezer mirror that's very powerful ( 10X ), but it's only 3"
across and too small to be used conveniently for eye make up.

Roly wrote:

She'd be better off with contact lenses.

She's tried contacts but can't get on with them.

She's also tried glasses where each lens individually flips down and
she's tried a monacle too.

Each of those solutions causes further problems for her, but the
mirror & magnifying glass solution has worked well for more than ten
years. However it's inconvenient to hold it all together, so a
stronger magnifying mirror appears to be the ideal answer.

Boots do a Tweezer mirror that's very powerful ( 10X ), but it's only
3" across and too small to be used conveniently for eye make up.

This type should make her eyeballs huge. :-)

http://tinyurl.com/ku8py

--
Sir Benjamin Middlethwaite

The3rd Earl Of Derby wrote:


This type should make her eyeballs huge. :-)

http://tinyurl.com/ku8py

Sadly it's a magnifying glass rather than a mirror. What she really
wants is a reasonably strong magnifying mirror as it's much simpler to
use.

But interestingly, the Maplin's description says that it has a 3 dioptre
lens, 1.75 X magnification.

That's the first time I've seen a reference that correlates the two ways
of measuring magnification.

Is it appropriate to extrapolate those figures ?

I assume that by holding a lens to a mirror, a 3 dioptre lens
effectively becomes a 6, due to the light passing through twice.
Therefore as she knows that a 3 dioptre lens and a mirror work for her,
then presumably we can assume that the magnification is 2 x 1.75 = 3.5,
so a 5X mirror should be suitable as she has found that a 3X doesn't do
the job.

Is there an obvious flaw in this reasoning ?

My intuition suggests that the difference between 3 X and 3.5 X is not
particularly obvious, but she has no joy with the 3 X mirror, but good
results with the flat mirror and lens ( which in reality is just a
little under 2.8 dioptre ) which should provide a little under 3.5 X.
That leads me to believe that the formula doesn't work quite in the way
that I am assuming.

"Roly" wrote in message
om...
Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye make-up
because she can't reach her eyes with the glasses on and can't see her
reflection with them off.

How about trying a fresnel magnifier, or two, in contact with the mirror
~5" x4" types are available at about £3 each post paid

e.g. the Midi Sheet magnifier on the page below.
http://www.magnifyingglasses.co.uk/a...nifiers_8.html

(I've used them as low priced fresnel lenses for my LF cameras' ground glass
screens. )

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

Roly wrote:
The3rd Earl Of Derby wrote:


This type should make her eyeballs huge. :-)

http://tinyurl.com/ku8py

Sadly it's a magnifying glass rather than a mirror. What she really
wants is a reasonably strong magnifying mirror as it's much simpler to
use.

But interestingly, the Maplin's description says that it has a 3
dioptre lens, 1.75 X magnification.

That's the first time I've seen a reference that correlates the two
ways of measuring magnification.

Is it appropriate to extrapolate those figures ?

I assume that by holding a lens to a mirror, a 3 dioptre lens
effectively becomes a 6, due to the light passing through twice.
Therefore as she knows that a 3 dioptre lens and a mirror work for
her, then presumably we can assume that the magnification is 2 x 1.75
= 3.5, so a 5X mirror should be suitable as she has found that a 3X
doesn't do the job.

Is there an obvious flaw in this reasoning ?

My intuition suggests that the difference between 3 X and 3.5 X is not
particularly obvious, but she has no joy with the 3 X mirror, but good
results with the flat mirror and lens ( which in reality is just a
little under 2.8 dioptre ) which should provide a little under 3.5 X.
That leads me to believe that the formula doesn't work quite in the
way that I am assuming.

Oh! bugger, ok try this for size :-) get a surveilance camera and 22" TV,
put the camera on top of the TV,point the camera at her face and zoom in
close enough to her eye...hey presto eyeball on TV.

Stop blinding me with optics equations.
--
Sir Benjamin Middlethwaite

The3rd Earl Of Derby wrote:


Oh! bugger, ok try this for size :-) get a surveilance camera and 22"
TV, put the camera on top of the TV,point the camera at her face and
zoom in close enough to her eye...hey presto eyeball on TV.

Stop blinding me with optics equations.
--
Sir Benjamin Middlethwaite

Another thought has she tried a mans shaving mirror? you can get these with
some magnification.

http://tinyurl.com/hbxf9

--
Sir Benjamin Middlethwaite

Roly wrote:

I know that if she uses a 3 dipotre magnifying glass on a plain mirror,
she can see OK, but the problem is that a mirror will be labelled as 3X
or 5X, whereas a lens gets categorised by dioptres or focal length.

the dioptre measurment is the reciprocol of the focal length expressed
in meters.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

For a simple lens like a magnifing glass, the magnification will be
given by f/f-s f is the focal length and s is the lens to object distance.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Roly wrote:

I know that if she uses a 3 dipotre magnifying glass on a plain mirror,
she can see OK, but the problem is that a mirror will be labelled as 3X
or 5X, whereas a lens gets categorised by dioptres or focal length.

the dioptre measurment is the reciprocol of the focal length expressed
in meters.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

For a simple lens like a magnifing glass, the magnification will be
given by f/f-s f is the focal length and s is the lens to object distance.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

(Roly) wrote in
om:



She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I don't know if either of these will help.

http://onlineshop.rnib.org.uk/browse...c=214&it=1&l=3


Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

My other suggestion is that you post this query in

uk.sci.astronomy

What they don't know about mirrors and lenses (reflectors and refractors)

prolly isn't worth knowing

mike

On Fri, 31 Mar 2006 23:05:24 GMT, (Roly)
wrote:


She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I know of someone in a similar position who uses one of these:-

http://www.precisionproducts.us/detail.asp?c=Magnifiers-Readers&s=%20&s2=%20&sku=3011A&r1=&r2=&r3=

They have it taped to a mirror and it gives magnifying mirror with a
"working distance" of about 6" and enough magnification. Maplin
appear to do one for about GBP6

http://www.maplin.co.uk/Module.aspx?...2329&T=264 42



--
Peter Parry.
http://www.wpp.ltd.uk/

On Fri, 31 Mar 2006 23:05:24 GMT, in uk.d-i-y
(Roly) wrote:

Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye make-up
because she can't reach her eyes with the glasses on and can't see her
reflection with them off.

She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I know that if she uses a 3 dipotre magnifying glass on a plain mirror,
she can see OK, but the problem is that a mirror will be labelled as 3X
or 5X, whereas a lens gets categorised by dioptres or focal length.

Is there a way to convert the preceived magnification as seen through
the lens & mirror t( n dioptre ) o get an equivalent rating as defined
for mirrors ( n times ) ?

Some links from my bookmarks may be of interest.

Practical optics info and FAQs at Edmund Optics
http://www.edmundoptics.com/techsupport/optics.cfm

Tutorial: Optics Reference Guide, has loads of optics formulae.
http://www.newport.com/servicesuppor...lt.aspx?id=111

Lenses, Mirrors by the ton
http://www.knightoptical.co.uk/acatalog/Lenses.html

Light and Optics Tutorials (Uni of Florida)
http://www.phys.ufl.edu/~phy3054/light/Welcome.html

University of Maryland demonstrations
http://www.physics.umd.edu/lecdem/se...subtopicsl.htm

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
Remove NOSPAM from address to email me

Roly wrote:
Apologies for straying off-topic, but I know there are a lot of clever
people here who might know the answer.

A friend of mine wears glasses and has difficulty doing her eye
make-up because she can't reach her eyes with the glasses on and
can't see her reflection with them off.

She can't readily find a magnifying mirror that's powerful enough, but
knows of some expensive mail order ones that claim to be stronger than
usual.

I'm in the same boat. I bought a mirror recently from Lidl which is
much better than any I've had before, don't know the magnification
though. It is about 6" across and has a suction pad on the back. I stick
it to a window where the light is good. It might or might not be good
enough for your friend but it was only about 7 euro I think so would be
worth a try. Keep any eye on the Lidl newsletters :-)
HTH
--
Holly, in France
Gite to let in Dordogne, now with pool.
http://la-plaine.chez-alice.fr

On Fri, 31 Mar 2006 23:05:24 GMT, (Roly) wrote:

|Apologies for straying off-topic, but I know there are a lot of clever
|people here who might know the answer.
|
|A friend of mine wears glasses and has difficulty doing her eye make-up
|because she can't reach her eyes with the glasses on and can't see her
|reflection with them off.
|
|She can't readily find a magnifying mirror that's powerful enough, but
|knows of some expensive mail order ones that claim to be stronger than
|usual.
|
|I know that if she uses a 3 dipotre magnifying glass on a plain mirror,
|she can see OK, but the problem is that a mirror will be labelled as 3X
|or 5X, whereas a lens gets categorised by dioptres or focal length.
|
|Is there a way to convert the preceived magnification as seen through
|the lens & mirror t( n dioptre ) o get an equivalent rating as defined
|for mirrors ( n times )

I have the same problem at the opticians, can't see what the new frames
look like without proper lenses in them.
He took a photo of me with one of these fancy mobile phones which I could
view with my real glasses :-)

I am sure that something could be rigged up with a webcam.
--
Dave Fawthrop dave hyphenologist co uk Google Groups is IME the *worst*
method of accessing usenet. GG subscribers would be well advised get a
newsreader, say Agent, and a newsserver, say news.individual.net. These
will allow them: to see only *new* posts, a killfile, and other goodies.