The Canon EF 85mm f/1.8 USM is older than the camera it is mounted on by more than three decades, and the pairing still produces the cleanest subject isolation this system can deliver at the price. Adapted to the R100 through the EF-EOS R adapter, the lens lands on an APS-C sensor with a 1.6x crop factor, which pushes the effective field of view to roughly 136mm. That reframing matters. The optical characteristics remain those of an 85mm — the same depth of field at a given distance, the same rendering of out-of-focus light — but the tighter angle of view forces the photographer further from the subject, and the compressed perspective does the rest of the work.