Canon's CM-V1 Locking EF Mount Kit replaces the Canon EF mount that comes attached to your C500 Mark II. The locking mount maintains the same electronic functionality of the standard EF mount, but locks your lens into the mount to prevent play. Cinema lenses, especially zooms, require that lenses maintain a precise distance from the image plane for best results; any play between the lens and mount can cause the lens to suffer from poor optical or mechanical performance.

The locking EF-C mount incorporates the EF mount electronic contacts and allows you to mount virtually any Canon EF mount lens, either the stills variety or the cinema lens variety, on your camera. The kit includes the locking EF mount and a shim kit for precisely adjusting the mount on your camera to ensure the correct flange distance.