[Recovered Thread: 113419]

[Bob Nichol]

You divide the focal length of the telephoto lens by the focal length of a normal lens for that format to get a rough idea of binocular power.

In the 35mm world this would be 200mm/50mm = 4x

Normal lens on a Nikon DX DLSR would be about 33mm and Canon 1.6 would be about 31mm. It's easier to multiply the telephoto by the crop factor and divide by 50! 200 X 1.5 = 300mm 300mm/50 = 6x

Do not confuse this number with the zoom X factor. Binocular power is a real number and zoom X factor is a meaningless marketing number.

[sgarthee]

Thanks. That would mean I would need about a 400 mm for the rough equivalent of 8x binoulars which on my Pentax would be about a 270 mm at 35mm equiv.

[sgarthee]

Thanks. That would mean I would need about a 400 mm for the rough equivalent of 8x binoulars which on my Pentax would be about a 270 mm at 35mm equiv.



Figured I should edit both since I double posted. :?

[eric s]

Bob is exactly right.
So your 8x binocs would be the same as a 400mm lens on a 35mm film camera.
A 200mm lens (on a 35mm film camera) would be the same as a 4x binocs.

Eric