At any given focal length, α digital SLR (Single Lens Reflex) with an APS-C size image sensor has a slightly smaller angle of view than a 35mm format camera, and yields an image that is about two-thirds in size. So if you are shooting with an APS-C format camera, it is useful to keep in mind a conversion factor of 1.5x. For example, a 50mm focal length is equivalent to 75mm in 35mm format.