The focal plane is further back on a camera that uses ef lenses than the that of the eos-m so in order to use those other lenses you need them further out from the eos-m focal plane. That's why the adapter is the length it is.
By Amazon Customer on May 17, 2014
You should be able to, as you turn the auto focus on and off on the EF ör EF-L lens body. The auto focus can't operate when it's set on manual on the lens body.
By Hilmar Fridjonsson on August 25, 2016