Binocular Magnification versus Camera Lenses?

Interesting question on the Canon forum, what 35mm lens would correspond to a

x10 magnification binocular?

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00NSc7

 

I guess ultimately it depends on the print size and the bino's field of view,

so essentially unanswerable. But can a camera lens ever be said to posess

a "magnification factor"?

It's an "apples/oranges" question. Binocular magnification is a reasonably exact specification that is derived by the ratio of the objective lenes focal length divided by that of the eyepiece lenses. On the other hand convention "magnification" of a given camera lens usually compares it to a 50mm focal length lens (for 35mm film cameras). Actual true magnification depends on the viewing perspective of the final print or projection. (It used to be figured as an 8"x10" print viewed at about 10" distance.)

Alex, come at it from the other end. If you made a pair of binoculars by (the unlikely route of) strapping two lenses/cameras together, then what magnification would that be?

50mm is 1x, 100mm is 2x, 200mm is 4x, so 10x would be about 500mm lens.

If you mean viewing through the camera eyepieces as a binocular, it all depends on the focal length of the camera's eyepiece. Both my F4S and F5 have 70mm focal length eyepieces so that would make a 50mm lens (50mm/70mm) equal to a magnification of about 0.7X. When I mount my 500mm and 1.4X TC it gives a visual magnification of 10X, which conveniently matches my 10X40 binoculars that I use to survey the landscape for interesting subjects.

Alex, yes that makes sense, I normally find a lens of about 70mm renders a scene in the

viewfinder at roughly the same magnification as the naked eye.