For using Canon EOS R RF mount mirrorless digital cameras with all Canon EOS EF mount lenses.
Switching shooting mode and focusing mode to M (manual) is recommended.
Allows focus infinity.
Not suitable for Canon EOS film / digital SLR cameras and EOS M EF-M mount mirrorless cameras.
Since there is no diaphram control, you can use the maximum aperture of Canon EF / EF-S lens only.