BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="henry link" data-source="post: 3585333" data-attributes="member: 6806">I agree with Alexis' post #31. The natural collimated light that falls on the eye exhibits neither field curvature nor astigmatism. Why would removing those aberrations from the collimated light that falls on the eye from the binocular eyepiece cause the image to appear unnatural? I don't think anyone would object to those corrections by themselves. As I've said elsewhere, I think the objections to the "naturalness" of the field in the SV and others are actually objections to a relative lack of pincushion distortion and the resulting large angular magnification distortion toward the edge of the field, something quite unrelated to correcting field curvature and astigmatim.As for eye darting, we all do it. Otherwise our heads would be in a state of constant jerking and twitching as we make small angular changes in our central gaze. I recall a few years ago Elkcub provided a link to a paper which found that the eyeballs can comfortably swivel over a range of about 35º before head movement is required. That's more than half the AFOV of the binoculars under discussion. Swiveling the eyeballs over 20 or 25º when reading or looking through a binocular probably goes quite unnoticed, which must explain why people can imagine that their eyes never dart around the field at all. My experience with the field correction of the Zeiss 8x42 FL (and the essentially identical HT) is that the "sweet spot" is just barely adequate over 20º of apparent field. I find better correction of field curvature and astigmatism than that to be a noticeable improvement with no down side.Henry</blockquote>

Verification