Sigma 20mm, f/1.4 DG HSM ART Canon EF (Canon EF-S, Canon EF, full size)

Sigma 20mm, f/1.4 DG HSM ART Canon EF

Canon EF-S, Canon EF, full size

Question about Sigma 20mm, f/1.4 DG HSM ART Canon EF

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Thomas Kämpfer

6 years ago

The lens also fits on a camera with an APS-C sensor, do I understand correctly that the focal length is then 32?

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michel.eichelberger

6 years ago

Helpful answer

That is correct.

For the sake of completeness, here is an explanation for others:
Due to the smaller sensor, only a section of the lens is effectively used, resulting in an angle of view similar to that of a lens with a focal length of 32mm. This is called the crop factor. Canon calculates this with a factor of 1.6.

Corresponding formula for Canon cameras with APS-C and EF lenses (caution, not EF-S):
20mm (full frame) x 1.6 (crop factor) = 32mm (APS-C)

Otherwise, a good explanation with example can be found here:
https://fotoschule.fotocommunity.de/cropfaktor...