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I have mild astigmatism, and some times wear eyeglasses or contact lenses. I've noticed that there is some mild visual distortion and chromatic aberration when wearing eyeglasses, as compared to not wearing them or wearing contact lenses instead.

I'm curious of how much of an impact,if any, would eyeglasses affect post processing. From my (limited) experience, I can't see any significant difference between photos I've processed while wearing eye glasses, and without.

Also curious if different types of eyeglass lenses affect vision differently. For example lens material and lens shape (for different types of vision correction).

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    @xiota To whether or not my natural vision has distortion and/or aberration: I don't know. I suppose I would have to visit my eye doctor to get that answer. I do know that barrel distortion in the periphery of glasses wearers is not uncommon. I'm wondering if any one else has noticed their wearing eyeglasses affecting the output of their post-processing work. – user82048 Feb 18 '19 at 1:24
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I have fairly significant astigmatism. I'm also myopic, more so in my right eye than in my left. As I age, hyperopia has set in and I'm not able to focus at close enough distances to reduce the impact of the myopia enough without corrective lenses. With unaided vision, I can see most clearly at a distance of about 10 inches with my right eye, and at about 20 inches with my left. Unfortunately, at 10 inches my unaided left eye is blurry and at 20 inches my unaided right eye is even worse. So when I sit at a computer I must either:

  • Wear gas permeable contact lenses that correct the astigmatism and the myopia and reading glasses to deal with the hyperopia

or

  • Wear glasses made for use at a specific distance (mine are set for about 18 inches). They combine my normal prescription with a diopter adjustment for close vision.

When wearing external lenses, such as glasses, there will be aberrations such as geometric distortion and some of the wavelength/chroma related classic aberrations. After all, your eyeglass lenses are, at best, a single element lens.

Reading glasses tend to be worse in these respects. Probably because they're made very cheaply, but also because their main purpose is to magnify enough for a farsighted person to focus closely, not to present a rectilinear view of the world free from chromatic aberration.

Contact lenses act a bit differently than external lenses because of the tear layer that fills the gap between the back of the contact lens and the front of the cornea. In a sense, a contact lens is an extension of your cornea. The contact lens has roughly the same refractive index as the tear layer, and thus combined with the tear layer acts as an aspherical corrector where astigmatism caused by a cornea with a non-spherical surface is concerned.

I've found the best way to deal with the geometric distortion is to use grid lines imposed over the image when trimming/cropping/tilting/rotating images.

Although I have at times noticed the effect of mild CA when looking at bright things from a distance, I've never really experienced that when sitting at a computer screen. If it did happen, zooming in on a specific area of the image, a/k/a "pixel peeping" would make it easy to see if any chromatic aberration one perceives is due to the limits of one's vision or to the presence of CA in the image itself.

  • Symbolic +1 for personal experience and tips! – user82048 Feb 18 '19 at 6:31
  • Don’t forget that many eyeglasses have anti-reflective coatings. Because of the physics of AR coatings they will preferentially reflect a single narrow frequency band, introducing a subtle tint into the transmitted light. If you use reading glasses, try to find ones without AR coating. – Jim Garrison Feb 19 '19 at 4:31
  • Also, contact lenses are usually lightly tinted blue, which can also shift color perception. – Jim Garrison Feb 19 '19 at 4:33
  • Re: AR coatings. I didn't stay in that fad long. They scratched too easily for my lifestyle at the time. Plus I was only buying glasses for backups to contacts during that time period. RE: blue tinted contacts. That depends on whether your optometrist gives you the option of a microscopic dot instead or not. – Michael C Feb 19 '19 at 9:04
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Just another personal experience.

I have a mild myopia (-3) and very mild astigmatism. With soft contact lenses that I wear near constantly, my vision is near perfect in all regards.

However, when I occasionally wear glasses, I find both the geometric distortion and chromatic aberrations intolerable. I guess I could live with that, but it makes all but the most basic photo processing impossible for me.

Given that our eye itself is far from perfection and many corrections are done in-brain, we can get used to distortions rather quickly. As we see the whole world distorted and not just the photo in question, we should be able to process photos correctly, even if with some mental effort initially.

It's harder to deal with chromatic aberrations. We can learn not to notice them, but if you are deliberately looking for them in the photo, you'll see them all. The only workaround is to look direct at the affected area: there the 'induced' aberrations should be minimal. I certainly end up with much more head movement when I have to edit photos wearing glasses.

Here is where there is a fundamental difference between contact lenses and eyeglasses: the lenses move with the eyeball and follow your gaze, whereas glasses don't, yielding different distortion/aberration depending on the direction you look. You need to move the head more, which is less natural and more tiresome in my experience.

All-time glass wearers may claim they don't notice any inconvenience or problems. Indeed they usually don't. But it would be an interesting research to learn if they actually yield the same result in, say, chromatic aberration corrections when processing photos. I suspect that on average, they will be more tolerant to them...

In the end, like you, I may (and usually do) end up with the same processing result when wearing glasses vs. lenses, but I certainly have to put more effort with glasses.

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The eye contains a single lens, along with the distortions and aberrations that entails. The defects, such as a large blank area, are corrected with advanced image processing algorithms. After a sufficient amount time is spent wearing glasses, images will automatically be adjusted to correct the distortions and aberrations. The adaptation period may vary with the age of the equipment and processor. Adaptation would not occur if the user does not consistently wear the corrective lenses.

... how much... would eyeglasses affect post processing [?]

Corrective lenses are expected to improve visual tasks, including post-processing work, unless the lenses are tinted or designed for the wrong prescription. The improved performance when wearing lenses might not be noticeable to the wearer. For instance, someone with astigmatism might over sharpen images when not wearing corrective lenses. Any peripheral distortions or aberrations are unlikely to affect most people's work unless they work primarily from their peripheral vision.

Also curious if different types of eyeglass lenses affect vision differently.

They do because they're correcting for different vision defects. But in nearly all cases, any vision-dependent work by people who wear such lenses would be expected to improve.

  • Astigmatism with one's vision is not exactly the same thing as astigmatism with a camera lens. It's a case of the same term being used slightly differently in two related fields. Rather than primarily causing differences between radial and tangential lines, astigmatic vision causes geometric distortion in irregular shapes. – Michael C Feb 18 '19 at 5:32
  • Have you actually ever worn glasses? – Michael C Feb 18 '19 at 5:35
  • Have you had any formal training in diagnosing and fixing human biomechanical failures, including eye conditions? – xiota Feb 18 '19 at 7:05
  • No. But from 47+ years of wearing glasses and 35+ years wearing rigid gas permeable contacts I can certainly confirm that glasses do introduce geometric distortion such that square or rectangular objects will look curved. As someone with asymmetric astigmatism I don't need any formal training to know what it looks like with (rigid) contacts, with glasses, and without any corrective lenses. – Michael C Feb 18 '19 at 8:27
  • And in your 47+ years of experience with corrective lenses, you've found that they've negatively affected your ability to perform visual tasks? – xiota Feb 18 '19 at 10:45

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