Full-frame digital cameras have an image sensor that is the same size as a 35mm film frame. When using a standard lens on a full-frame digital camera, the focal-length information printed on the lens does not need any conversion. In other words, a lens that states it has a 50mm focal length is in fact 50mm. It is the same as it would be on a 35mm film camera.
Digital cameras that are not full-frame use an image sensor that is smaller than a 35mm film frame - for example, an APS-C image sensor. To determine the 35mm equivalent focal length for cameras that use a APS-C sized image sensor , it is necessary to multiply the focal length of the lens by 1.5 times.
IMPORTANT: Digital Technology (DT) lenses are designed for cameras with APS-C sized sensors and not recommended for use with full-frame digital cameras.