Conclusion

The Canon RF 100-500mm F4.5-7.1L IS USM is a incredibly capable but also incredibly expensive telephoto zoom lens.

It will most strongly appeal to sports and wildlife photographers looking for a relatively lightweight and versatile all-in-one zoom lens.

Compared to the EF 100-400mm f/4.5-5.6L IS II USM DSLR lens that it most closely resembles, the new RF 100-500mm principally offers an extra 100mm of telephoto reach, albeit at a pretty slow maximum aperture of F7.1.

Somewhat disappointingly, the RF 100-500mm's maximum aperture at 400mm is F6.3, which is slower than the EF 100-400mm's maximum aperture of F5.6 at 400mm.

Still, the extra reach does make the new RF 100-500mm F4.5-7.1L IS USM more versatile than the DSLR lens.

Given its L-series billing, as you'd expect the Canon RF 100-500mm F4.5-7.1L IS USM build quality is reassuringly excellent, with the usual weather-proofing that all L-series lenses benefit from.

Auto-focusing proved to be both satisfyingly quick and very quiet, with the ability to manually override it and focus manually if required proving a nice touch.

The very capable image stabilisation system goes some way to making up for the relatively slow maximum apertures.

Although the RF 100-500mm is just about light enough to hand-hold for long periods of time, for best results the use of at least a monopod is advised.

Image quality is outstanding. Both center and edge sharpness are excellent even when shooting wide open throughout the zoom range, chromatic aberrations are very well controlled, and bokeh is impressive despite the slowish maximum apertures.

The only real optical issue is some vignetting when the lens is set to its maximum aperture, but this can be easily corrected in post-processing.

If you want to use this lens with the new RF 1.4x and 2x extenders, it's only compatible when the lens is extended to between the 300-500mm focal range, which makes transportation tricky unless you temporarily remove the teleconverter.

The new Canon RF 100-500mm F4.5-7.1L IS USM improves on its popular DSLR predecessor in a lot of ways - it's sharper across the frame and throughout the zoom range, has a more effective image stabilisation system, is lighter and more compact, offers faster autofocusing, features a fully removable tripod collar and a customisable control ring, and extends further to offer 100mm extra reach.

If you can afford the sky-high price-tag, then we can certainly recommend the Canon RF 100-500mm F4.5-7.1L IS USM as a simply brilliant telephoto zoom lens for Canon full-frame mirrorless camera owners.

Ratings (out of 5)
Design	4.5
Features	5
Ease-of-use	4.5
Image quality	5
Value for money	4