A:AnswerTo further expand upon my prior answer, the Canon EF to EF-M adapter allows you to use EF and EF-S lenses with the Canon EOS M mirrorless camera line. The adapter is powered by the camera and has electronic contacts. This allows the camera to enable autofocus, aperture control and access to EXIF data (your pictures will include metadata that will mark what lens was used, focal length, aperture, shutter speed, etc.). If you choose not to use autofocus, the EOS M5 is able to use "focus peaking". When enabled, you will see colored dots (you can choose red, yellow or blue) that will show what edges are sharply in focus when using manual focus. In addition to this, you can enlarge your view up to 10x on the electronic viewfinder or the back LCD screen to assist you with manual focusing.