* VILTROX EF-E II Electronic Adapter (F Booster) only for Canon EF lens, not for EF-S lens . * Reduced imaging focal length, the actual focal length after using EF-E for 0.71 times the focal length.Also compatible with full frame camera , just please turn on the APS-C Mode firstly . * Dedicated switch to select between Contrast Detection and Phase Detection Auto Focus mode . CDAF allow Flexible Spot to be moved and focus across the frame and support Eye focus on specific camera . PDAF gives faster focus experience on most lenses. * With USB port firmware update . latest firmware can be download from official website, connect adapter to computer with USB cable and copy the file into adapter memory. Do not required to attach lens or camera. * Ring at the bottom with 1/4 screws, which can easy installed on the tripod or other fixed bracket.