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Does an EF-S lens' focal length have the 1.6 crop factor already calculated?

bryannemarie
Apprentice
For example, the kits lens that is often 18-55mm purchased with a canon rebel, since it is specifically made for crop-sensored camera, is it a 'true' 18mm focal length, just as an 18mm EF lens would be on a full frame camera (other than smaller field of view)? Or to get the 18mm focal length effect, would you still need to purchase something closer to a 10mm EF or EF-S lens?
11 REPLIES 11

Okay, thanks.  I'm just a part-time math guru.

 

FYI, I've found a formula to convert focal length to FOV.  The formula that it implements is FOV = 2 arctan (x / (2 f)), where x is the diagonal dimension of the sensor. The FOV is measured across the sensor's diagonal, and is therefore smaller across the horizonal dimension, and even smaller across the vertical dimension.

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"The right mouse button is your friend."

It's not that hard.  Just remember 46 is normal.  Anything below is WA and anything above is tele.

EB
EOS 1DX and 1D Mk IV and several lenses!
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