Canon RF 135mm F1.8 L IS USM

Testers rank it among the sharpest lenses they have measured. It is very sharp across the whole frame from f/1.8, and stopping down adds almost nothing. Lateral colour is negligible, longitudinal fringing is very low for the aperture, and distortion is a trace of pincushion. Autofocus is fast and quiet, and the stabiliser makes slow shutter speeds practical for portraits in dim light.

The drawbacks are raw vignetting of more than 2 stops at f/1.8, which the camera profile removes, and a background blur in the transition zone that can look busy in some scenes even though highlights are smooth. It is larger than the EF 135mm f/2L and front-heavy on small bodies. The engineered-plastic barrel is solid and sealed, and the price is high, especially outside the US.

Owner reports are few but positive. One owner says it delivers the image quality expected and does not feel unwieldy, but finds it a specialised and less versatile lens than an 85mm. Others weighing it up point to the long working distance needed at 135mm.

Price comes up again and again: one would-be buyer plans to rent it first and is looking at a used EF 135mm f/2L instead, and an owner of the EF lens says they will keep it.