Join Date: Apr 2006
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Re: Binocular Conundrum: Field of View?
I understand what you are saying, but from what all the binoc makers say, the size of the exit pupil effectively "crops" the size of the image coming out of the binocs and into your eye. So assuming an exit pupil size fo 5mm, the focused image in your eye, on your retina, will be constrained by the 5mm circular image of the exit pupil size of the binocs.
To use some arbitrary numbers, let's say binoc #1 has a FOV of 500 feet, while binco #2 has a FOV of 250 feet, while both have the same 5mm exit pupil size.
Shouldn't that mean that binoc #2 has twice the magnification as binoc #1, since it is showing half as much FOV, but putting the same size (5mm cropped) image into your eye?
If the image that is projected into your eye is the same size, the FOV and magnification MUST be the same for both binocs, mustn't they? If you increase the magnification, the FOV has to decrease, if the image at the exit pupil is the same size. And if the FOV gets wider, then the magnification has to proportionately decrease, doesn't it?