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I wear glasses for an astigmatism. When taking photos, I find that my eyes lose focus almost right away, since one eye is closed and the other is looking through the viewfinder.

This happens whether or not I wear my glasses, so I usually just wear them.

Naturally, this makes it difficult to a) evaluate photos and b) know whether or not I'm actually focused properly. Photos will look fine to me on the camera but then on the computer they're unusable.

Has anyone else experienced this and/or have any ways to deal with it?

  • Do you mean that you find it hard to focus with the eye that is looking through the viewfinder, or your eye(s) find it harder to focus after looking through the viewfinder? – HamishKL Feb 1 '16 at 3:00
  • My right eye, they eye I don't use to look through the viewfinder, is crazy blurry after I look through the viewfinder. This also strains my left eye trying to see with both eyes open. – Azor Ahai Feb 1 '16 at 4:04
  • Interesting.I began experiencing the same thing at age 21 after squinting through a viewfinder for several minutes at a very contrasty and defocused macro subject. It has plagued me ever since to a greater or lesser degree, depending apparently on subject magnification. It is much less of a problem if i don't close my other eye however. My theory is that the repetitive muscular imbalance for the non dominant eye being squashed and "deactivated" every time you use the other eye to look through the viewfinder causes it to lose "focus synchronisation" with the other eye... – HamishKL Feb 1 '16 at 4:45
  • ...but I have found that the problem can be quickly reversed somewhat by (this is hard to explain) intentionally defocusing the weak/affected eye and looking at a very high contrast, tiny light source, then focussing on the defocused star point. You should see the tiny star sharpen into clear focus, while everything else is way out of focus. This effectively tricks your eye muscles into focusing on something in a range you never normally use and seems to "reset" the eye muscles. It's not perfect, but in my case it corrects about 80% of the problem in about 1 minute. – HamishKL Feb 1 '16 at 4:51
  • A good example light source I use is distant street lights at night, but the same thing can be achieved in the day with bright glancing reflections off of dust particles on sunglasses, windscreens, etc. The trick is that you are focusing on the defocused light point (i.e. literally focusing on the image of the airy disc), not the actual light source itself. You sort of need to go cross-eyed to achieve this, but it's not hard to do. – HamishKL Feb 1 '16 at 4:58
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Although cameras often have diopter correction, your problem may be due to the astigmatism issue, for which there is no simple adjustment. However, if the viewfinder eye-lens is removable, a custom lens can be ground to correct for your astigmatism. Another possibility is to have such a lens made to overlay a non-removable eye-lens, but you would probably have to work together with an optician willing to experiment. An overlay might also restrict the field of view, though not as severely as do glasses. Note that the corrective lens is asymmetric and must be correctly oriented (or orientated when in GB).

BTW, I've noticed the same issue you describe, particularly after using a microscope or telescope for lengthy periods. Microscopists are taught to keep both eyes open and to ignore the view from the eye not looking through the microscope to avoid eyestrain. Alternatively, the ambidextrous (and ambiocular?) microscopist can look at paper with the off-eye to make a "tracing" of what's under the microscope. This may not be practical in photography, though, where a bright sunlit view would distract from that through the viewfinde.

  • Sounds like I really just need to talk to an eye doctor, but thanks for the suggestion. – Azor Ahai Feb 2 '16 at 1:08
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I believe adjusting your camera's diopter to match with your eye power will solve this issue. It is very important to set the diopter prior to take any photos. You can find more information here

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    If the OP is referring to the same issue I experience, setting a different viewfinder diopter doesn't help; it's a problem with the other eye being squished while the viewing eye is doing focal gymnastics. – HamishKL Feb 1 '16 at 5:54
  • HamishKL is right. I have messed with the diopter, the problem isn't my left eye being out of focus, it's my eyes not agreeing with each other, if that makes sense. – Azor Ahai Feb 1 '16 at 6:26
  • May I know how it relate to the photography question then? It shows there is some issues with eye synchronization (if I'm not wrong). I think this behavior will appear not just while taking photos but anytime you focus similarly. Correct me If I'm wrong. – Ajith P Venugopal Feb 1 '16 at 6:46
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    In my case it only occurs when photographing and is likely an issue many photographers (and astronomers?) experience. – HamishKL Feb 1 '16 at 9:39
  • @Ajith The only time I focus with one eye closed and the other one focusing very near to my face is when photographing. The effects make it hard to photograph. I hoping to find out if other photographers suffer similarly. – Azor Ahai Feb 1 '16 at 19:22

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