Canon's EOS R support list excludes EF-M from the EF-EOS R adapter route. EF-M and EF are distinct mounts despite similar lettering.
Make the exact-model decision
Inspect the rear mount and Canon's camera compatible-lens list; do not force an EF-M lens into an EF adapter. First identify the physical mount on the camera and lens, not just the maker name. A body may support a separate older family only through a named adapter.
A manufacturer example
Canon’s EOS R6 Mark II support page separates native RF/RF-S lenses from EF/EF-S lenses that require an EF-EOS R adapter and excludes EF-M from that adapter route. Use the linked page for its stated model and revision; a different model may need a different support document.
Where to draw the line
A match in the mount label establishes a route to investigate; it does not prove image coverage, AF mode or rear clearance. If a source does not address the exact feature you need, record that feature as unknown rather than treating silence as support or incompatibility.
Your next step
Take the model code from the body or lens label, open the official source below, and compare its scope with the equipment you have. Then use the compare mount systems to organize what is known. Do not mount an item that resists or appears on a maker’s exclusion list.
Official sources and scope
Checked for this reference on October 30, 2026. Product firmware and support lists can change; inspect the current maker page for your exact revision.