Who understands diopters?

[Kevin J. Kolosky]

I was given an old R B67 camera that is in fairly good condition and I wish to use it. I wear glasses. When I put my eye up to the eye level viewfinder I cannot focus. Everything remains blurry no matter what I do. However, if I put my head back about 6 inches or so from the viewfinder everything becomes clear and I can focus.

So I would assume I need a diopter. (or don't I) If I do, how do I know how strong or how weak it should be. Positive or Negative. How does one determine this.

[cowanw]

Is there an eyepiece correction lens on the eyepiece now? If so extract it. You may already have a diopter on it.
Do you have a waist level finder which works?
Do you wear bifocals. If so look through the correct portion.
Basically if you are using glasses that you can see infinity with then normally you should see correctly in the viewfinder, assuming the camera and lens are OK.
Lastly your eyeglass prescription tells you how many diopters you need when you do not wear glasses to look through the camera. Ask the people who make your glasses.

[William Whitaker]

When you say 'diopter' do you mean the measurement (as in 'the reciprocal of the focal length expressed in meters') or do you mean an accessory lens that attaches to a viewfinder? At first read (and from the title) I thought your question was about the former, but now I think I misunderstood.

[mdarnton]

The easiest strategy may be to go to a drugstore with your camera and find the reading glasses that work best through the finder, then order that lens for your camera. Most camera finders are set to a virtual 1 meter distance, so your glasses prescription will probably not be exactly right.

[Sevo]

Is that with or without glasses? What finder do you have, and what diopters do your glasses have?

[aclark]

I didn't need glasses when I bought my OM1 in 1980, and the image in the viewfinder was sharp and clear. Now my distant vision has deteriorated slightly I have glasses, that I don't normally use, but wear them for watching TV. When I tried wearing them to look through the viewfinder of the OM1 the image was sharp and clear. But I couldn't get my eye close enough to the viewfinder to see into the corners of the frame. I asked my optician to sell me a lens wih the same specification as my right spectacle lens, which I was told was +1 Diopter. The lens they sold me was circular; 2" diameter. It cost £19. I cut the central part into a rectangle that fits tightly into the eyepiece of the OM1, where it now lives permanently, and the image in the viewfinder is sharp and clear again.

Alan

[Drew Wiley]

Just ask your optometrist which strength diopter would be best, or else guess it from which reading glass strength works best. I don't like glasses per se because
flare sometimes gets into that distance between eyepiece and actual eye. Adjustable diopter magnifying eyepieces are wonderful, but not many cameras have them. Generally they're found on "chimney" or "hood" type finders for MF cameras.