Tool paradise since 1999
Visual acuity is of great importance in binoculars, as it is in
photography. The resolution or
resolving power must be good in order to be able to render enough
details. The edge sharpness is also of great importance. In cheaper
binoculars (and camera objectives), the edges around the image will
be slightly fuzzy and blurred compared to the centre of the image.
This is more of a problem with a camera since once an image is
captured, it cannot be changed afterwards. However, with
binoculars, you can scan the image as it were. You can therefore
make as much use as possible of the best part of the image, namely,
the centre. Yet, you will probably be irritated and disheartened if
the edges show poor image quality.
Just to put this into some perspective, you can of course camouflage a lack of edge sharpness by limiting your field of view. If you do this, you will not actually notice that the image quality at the edges is inferior. Yet, in practice, it is better to have a larger field of view after all because then, it is far easier to 'find' a subject. And as soon as it is in focus, you can use the better part of the image, namely, the centre part, to see as many details as you can.