Viltrox C-AF 2XII TELEPLUS can make the focal length of all the for Canon EF lens increased to 2 times,and the auto-focus function of the original camera lens can be used perfectly, and don't change the EXIF information. Compatibility: C-AF 2XII is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200mm f/2.8L, EF 70-200mm f/2.8L IS, EF 70-200mm f/4L, and EF 100-400mm f/4.5-5.6L. Features: Compatible for Canon EF Mount Lens(not for Canon EF-S lens). Can increase the original lens focus length to 2 times. Support lens Auto Focus function and won't affect to Exif information. Adopt 7 optical glasses, 4 groups, the depth of field is half of the original lens. Good helper for long distance photography. With upgraded USB firmware interface. Specifications: Mount type:Canon EF-Mount lens Magnification:2 times Depth of Field:Half of the original lens Min stacking focal length:Equal to the original lens Constitution of the lens:7 glasses, 4 group Focus mode:Auto focus Lens Coating:Multi-coated Exposure factor:Approx. 4 times (equal to 2 aperture ) Diameter and length:Approx. 68×51mm Weight: Approx 154g Package Listing: 1 x Viltrox C-AF 2X II TELEPLUS Adapter 1 x Product?'s Manual