Peterff wrote:
Actually you need one for anything that is not an EF-M lens, unless I have completely failed to understand the situation. In the Canon realm you can get adapters for EF, EF-S, and FD. Nikon and Pentax and other format adapters are available. The mirrorless form factor brings many things into play, but they do need adapters.
I'm guessing, though, that EF and EF-S lenses will work as well on an EOS-M as they do on a Rebel, while KAF3-mount lenses will not work as well on an EOS-M as they do on my K-30,