Armchair Optometrist

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Last night I went to my optometrist and was examined with, what else, Leica microsystems equipment! (BFD you say) However, that inspired me to ask the good doc if the use of diopters would help me focus faster and more accurately with my M. He put me through the drill of adding .25 power increments to the phoroptor and I learned that diopters are great for magnification purposes but useless if you have an astigmatism. So my question/comment is; why not use a diopter to achieve maginifications of less than the standard 1.25x, and how about some corrective elements from Leica for those of us with an astigmatism? A new potential line of revenue for the company, and better yet the insurance company may pay for it! What are your thoughts?

-- Brooks (Bvonarx@comcast.net), March 06, 2002

Answers

I just went through the identical analysis: no diopters to correct astigmatism from Leica. My optometrist says that making diopters to correct this common condition would be difficult because the glass itself would have to be uneven & set (or aligned) precisely inside the finder. The technical difficulties may be what deters Leica from trying-- BTW, Hasselblad is identical, so this is not just a Leica problem...

-- Patrick (pg@patrickgarner.com), March 06, 2002.

I'd bet they're not still available, but Leica did once supply eyepieces with correction for astigmatism. That was in the days when they were more concerned with making accessories to adapt their cameras for any photographic situation, and less concerned with special models to celebrate bridge/sewer plant openings.

-- Wilhelm (wmitch3400@hotmail.com), March 06, 2002.

Leica never supplied eyepiece correction lens for astigmatism because there would be too many different combinations. Leica did, and still does, supply a mount into which you can have your optomtrist put in a custome lens to suit you. The lens element can be rotated when you switch from horizontal to vertical framing. Some people find having to rotate the eyepiece irritating and do not bother with astigmatism correction.

-- John Collier (jbcollier@powersurfr.com), March 06, 2002.

don't many of the LTM cameras have diopter correction?? why couldn't this be incorporated into the M?? is the greater eye relief of the M rf a substitute??

-- roger michel (michel@tcn.org), March 06, 2002.

How odd this thread came up. Just minutes ago I returned from the post office after returning a -1.5 Leica diopter to B&H because it make viewing worse for me. I, like many others, have gross astigmatism problems and I was trying to fix myself up to use my M6 without glasses. Doc says the only way to do that is yo go to contacts or laser surgery; both of which I would still be wearing reading glasses. What a bummer. I also had to return my diopter for my Canon EOS-3. I guess I should be happy I can 'see' without really being able to see. ---------------------------------------------------------------

-- Dayton P. Strickland (daytonst@bellsouth.net), March 06, 2002.


Here's a little more amateur optometry: I saw somewhere that there's a "spherical equivalent" to an astigmatism (cylinder) correction. I know it can't be a perfect correction, but possibly the spherical equivalent could be added to the other spherical prescription to get an adequate correction. (?)

-- Bob Fleischman (RFXMAIL@prodigy.net), March 06, 2002.

Brooks, when you mention the standard 1.25x, are you talking about the add-on 1.25x magnifier?

-- Bob Fleischman (RFXMAIL@prodigy.net), March 06, 2002.

Yes sir, I am referring to the add-on magnifier, (BTW I use the MOR .72 viewfinder). To my understanding one can create an interim magnification power using diopters (.75x instead of 1.25x) and/or increase magnification beyond 1.25x using a combination of add-on mangifyer and diopter. The second scenario seems to become impractical at some point due to loss of edge to edge visibility within the viewfinder. Is this a correct understanding or am I thinking to much. Thank you for your thoughts.

-- Brooks (Bvonarx@comcast.net), March 07, 2002.

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