Review by Klaus Schroiff, published May 2022

Introduction

In terms of build quality, it is certainly on a different level. While it's still based on some kind of advanced compound material. it certainly feels sturdy. On top of this, it is sealed against dust and moisture. Unlike its cheaper cousin, it also doesn't extend during focusing so in combination, it's much better prepared for more difficult outdoor environments. The focus ring operates smoothly and there's also the usual customizable "RF" control ring. And the rings don't even stop here. There's another one. :-) A special feature of the RF 100mm f/2.8 L USM IS macro is the "Spherical Aberration Control Ring". Basically, it allows you to deliberately introduce an optical defect that alters the way the lens is rendering images - more on this later. The combination of macro-and SA capabilities has somewhat super-sized the lens, unfortunately. It's the longest 100mm macro that we have seen to date. A barrel-shaped hood is part of the package. A rotating tripod collar is optionally available.

Another improvement over its predecessors is the ability to focus down to a magnification ratio of 1.4:1. This is probably a good idea because some Chinese manufacturers are offering macro lenses that even can do 2:1 already. Macro lenses tend to be rather slowish when it comes to auto-focusing but that's not really the case here. The Canon lens incorporates a Dual-Nano USM drive which is pretty fast and quiet. If needed, you can still use a focus limiter switch to avoid focus hunting in tricky scenes.  Manual focusing works "by wire" but you barely notice the difference compared to mechanical coupling. The built-in image stabilizer is good enough for 5 f-stops - and up to 8 f-stops when combined with in-camera IS. This is certainly appreciated when shooting macro because things can get pretty shaky at very close focus distances. Whether it's truly a 5/8 f-stop gain depends on your degree of coffee intake.