With the arrival of the RF-S series lenses for the new APS-C cropped format EOS R mirrorless range, Canon now has five lens systems on the go – EF, EF-S, EF-M, RF and RF-S. As with EF and EF-S, RF and RF-S share the same lens mount but, differently to the DSLRs, you’re able to fit RF-S lenses to the fullframe EOS R bodies that will, of course, switch to the cropped format… so the effective focal ranges will be the same. And, also as with the full-frame mirrorless bodies, you can fit EF and EF-S lenses via the three mount adapters that Canon currently has available – the EF-EOS R, the EF-EOS R Control Ring adapter or the circular polariser alternative. If you’re planning to switch from your APS-C…