Article ID : 00007668 / Last Modified : 08/16/2015

How to determine the 35mm equivalent focal length of a lens when used with camera that has an APS-C sensor.

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The specifications shown on the front of each lens are always stated in terms of the 35mm format. To calculate the 35mm equivalent focal length when the lens is mounted on an APS-C digital SLR, multiply the stated focal length by 1.5.

For example, a lens with a 50mm focal length used on a camera with an APS-C sensor is equivalent to 75mm on a 35mm SLR film camera (50mm x 1.5 = 75mm).