If you check Binocular spec sheets, you might read stuff like 'field of view 200 yards at 1000 yards' for example.

This essentially means that with this binocs, if you view a subject that's 1000 yards away, you are actually seeing a field of view that's 200 yards across, in a perpendicular perspective.

Lets say if the 200 yard spec is mentioned as 300 yards in a different binocs, then it is 'wider' angled than the 200 yard job..

Which is probably why you get tunnel vision or a narrower field of view with high magnification scopes and a wider view with, er, a wide angle scope

This should help somewhat