Binocular Example

Can some biniculars have variable feild of view?

like for example, 5x, 10x, 15x on the same binoculars

There are zoom binoculars. The field of view shrinks as you zoom in to higher magnification.

Most telescopes use eyepieces that can be quickly switched. I have three on my 10″ telescope, giving 48x, 120x and 240x magnification. The field of view reduces accordingly. There are zooming eyepieces, but they are not very common.

But i also have a spotting scope that has only one eyepiece. It is fixed at 22x, about 3.5 degrees field of view.

I’ve been happier with binoculars and spotting scopes that do not have a zoom feature, in general. The zoom feature is very expensive to get right, and most of the time, the feature is poorly implemented to reduce cost. My $250 spotting scope is better than most of the $1200 zoom spotting scopes i’ve checked out. And the 100 giant zoom binoculars i tried out at the store were so badly out of alignment as to be worthless.

It’s even more complicated that this for telescopes. Two eyepieces with the same focal length will give you the same magnification on the same scope. But different designs may give you different field of view as a result. Typically, wide field of view eyepieces are very expensive.

Leica Ultravid HD binocular