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Message: <blockquote data-quote="Renze de Vries" data-source="post: 1515313" data-attributes="member: 10024">Ed,Interesting theory, could very well be right, i.e. play a role, apart from or in combination with my more humble suggestion: the dynamic eye.I learned from this forum - probably from you - that the eye is never at rest, it's on the move. Now imagine you're placing a small lens, the exit pupil, in front of the eye, quite rigid. Now the eye starts to move within the exit pupil and will constantly stray, inevitably, outside the optical axis. Where it will encounter all kinds of nasty, non linear phenomenae called distortion. The eye doesn't like that.Now when we are able to manipulate the lens (binocular) in a less rigid way, so that small movements of the exit pupil are allowed, maybe the eye will start 'learning', that is move along with the optical axis. And will encounter less distortion.I think it's possible we will interpret this as 'less tunnel effect'.PS. I find your experiences with the Zeiss 7x42 (the classic B/GAT I suppose) quite remarkable as this is the model par excellence for my eyes to really enjoy the wide view. The AFoV of the 7x42 isn't so ourageous at all (a quite normal 60 deg.) but my eyes say WOW!Renze</blockquote>