Can someone explain about eye relief.

[Klem]

Klem...I know nothing about the science behind this but look at the specs on any variable scope and you'll find a range for eye relief.

Fair comment, but it is a calculated point by the manufacturer of scopes, microscopes, binoculars and spotting scopes where it is most efficient to have your eyes. The range you are talking about is an inch max. You can go even further, pulling your head back making the vision from the ocular deliberately smaller and still hit the target. The field of view will be smaller but the centre of the scope with the cross hairs is still clear and usable (e.g. pushing a daytime scope forward on the gun to make space for a NVD). Or closer and still not get that circle any bigger and risk cutting your eyebrow with recoil. I see typical eye-relief ranges of about 1/2 inch on less. That's not a lot of latitude and like I say, you can go shorter or longer and still take the shot. It's just that in that 1/2" range the diameter of vision will appear the largest and in the middle of that range will be the calculated point.

[bj139]

This is probably what you are asking. I have seen through scopes that had magnification but a tiny circle field of view.
Think 22 rimfire scopes vs. centerfire riflescopes. I think the only way to judge this is to look through the scope.

https://www.cloudynights.com/topic/492188-apparent-field-of-view-how-is-this-determined/

[Drift]

Thanks LR and Klem. Thats what I was missing.