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Originally Posted by kennygee
Terry
Depends on the camera make. Assuming a Nikon this has a crop factor of 1.5 which has to be taken into account.
The calculation is Focal Length of lens X Crop factor. Then divide this by 50mm which is the same as a 1:1 magnification.
So for a 300mm used on a Nikon DSLR -
300X 1.5 = 450mm
Divide this by 50mm
This gives a magnification of 9 which would equate to a binocular rated at 9X.
On a Canon camera with a crop factor of 1.6, the 300mm lens would give (300 X 1.6)/50 = 9.6.
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Or, if you use my 43.5mm figure, you can have (near enough) 10x on a Nikon and 11x on a Canon!
Again, if you're using the camera as a sort of
ad hoc binocular you need to consider the viewfinder magnification (or reduction, rather!). As an example, the spec sheet for my 20D says: viewfinder mag, 0.9x at infinity with a 50mm lens, but this doesn't take into account the 1.6x crop-factor - the 50mm is more akin to an 80mm in the 35mm full-frame format