The Metabones Canon EF to Sony E-Mount T Speed Booster ULTRA II is designed to help you get the best possible results out of combining full frame glass and an APS-C sensor camera. The high quality glass increases the angle of view of a full-frame lens by 0.71x, and the maximum aperture by one stop. This effectively compensates for the 1.5x crop factor of APS-C cameras and provides an image like that of a full-frame lens on a full-frame camera.