OT: binoculars vs cameras

I was traveling recently, and found myself making photos of wildlife in low light with my Nikon Z50 + 50-250mm lens, handheld. Not ideal, but I’m not ready to invest in a fast long lens for something I do very infrequently.

But while I was shooting with my mirrorless, my wife was taking shots with her smartphone camera through a pair of binoculars, and the results are surprisingly good!

This got me wondering - how do binocular lenses compare to camera lens? What would be the effective aperture and focal length of a good pair of 7x42 binos?

Clearly wider than my F6.3 250mm, but I think probably not far from that focal length?

Just curious if anyone knows more about this.

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Well, at the bottom of this, the 7X is the magnifying “power” and the 42 is the diameter of the front, or primary lens. If you divide them, you get the “exit pupil” of 6, the size of the image you see at the back lens. I’m pretty sure the 42 and the 6 are in millimeters.

I think a 250 mm full frame camera lens would be approximately 5X, so you would be correct, the two are about the same, with the binoculars being somewhat stronger.