Lens Binoculars

Optics question about binoculars?

If you have a pair of binoculars, and put a camera onto the lens of the one of the binoculars, and take a picture of it, will the picture show the zoomed-in area or just what is inside of the binoculars?

It will typically show a dark ring and the image being seen through the binoculars because the camera lens opening is bigger than the rear optics of the binoculars. With proper mounting and closing down the aperture, you can use binoculars as a telephoto lens.
You will definitely not see the inside of the binoculars.

How to Make a Close-Up Lens With a Binoculars