Quote:
Originally Posted by Stonius
I had heard that, but I thought that was to do with the eye's ability to focus *in general*.
I thought field curvature was more about a focal plane that is curved. Achieving sharp focus for the middle makes the outside go out of focus, and vice versa. So I'm thinking that as long as your eye can achieve focus at all, curvature should be just as much of a problem at any age, shouldn't it? Unless the shape of your retina (ie; the focal plane of the eye itself) changes with age?
Cheers
Markus
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What, though, do you mean by "out of focus"? Even if the edge requires a slightly different focus than the center, if you can easily focus your eye on each, would you notice the field curvature? Probably not.
Even at 68, with some eyepieces that have a curved field, if I focus the eyepiece on a star halfway to the edge, I can see the entire field in focus, whereas if I focus on a star in the center, the edge appears to be out of focus. My eye still accommodates a curve of half the diopter change, but not the complete one.
A young person can easily handle a 2 diopter change and the eye will still see the field in focus.
Here is a scholarly article on the effects of aging and accommodation in the eye:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908311/