Trivia question. What is the dark ring around my scope FOV??

[mikle76]

It has come to my attention that some scopes have the look of peeking through a long tube while others a short tube. Why is this? Let me explain. It seems like my cheap 4x scopes have a nice big image through the ocular lens with only a thin dark circle surrounding the image from the light of the outside world but most (not all) of my variable scopes have a thick black ring and their 4x magnification looks much less than the fixed 4x image. What creates this and what is it called? There has to be a term for it in the scope making industry. What ever it is called I don't like it. I have an el-cheapo Simmons 8-point scope that I have always liked and it just dawned on me the other day WHY I liked it. It has the thin black ring like my fixed power 4x's and it is a 3-9x40!

 

[swgunner]

If i remember correctly it is called optical occlusion and is caused by incorrect eye relief.

 

[rcmodel]

+1

Any scope will have less then a full field of view, and that dark ring, if the eye relief is set too short or too long.

Moving the scope forward or back in the mount rings should clear things right up for you.

rc

 

[mikle76]

Thanks guys but it's not an eye relief issue. I can move the scopes all I want but the dark ring is, for the lack of better words, "built into" the scope. If I adjust the eye relief beyond the scopes design it only gets worse. The best and biggest view I can get through the culprit scopes still has a thick black ring like looking through crosshairs at the end of paper towel tube. It may be an affliction of only cheap scopes.

 

[jimsmith80]

Well you are both right,
it is eye relife, but moving the scope will not help because the scope does not have the nessary eye relife built in. This is why quality scopes cost more and are worth the money, take that scope of yours and look through it nex to a Leupold or equelant, and you will see what I mean. FYI You cannot get a good read on a scope indoors, find someone at your local range who will let you look through theirs. You will see what I mean

 

[Monkybrainz]

try getting one with an adjustable focus, if i zoom in too close on a target that is not too far off, the ring appears on my kids tasco scope. but its a tasco............