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Hands on: Canon RF 100-400mm f/5.6-8 IS USM review

We took a closer look at Canon's newly announced Canon RF 100-400mm f/5.6-8 IS USM at The Photography Show

Canon RF 100-400mm f/5.6-8 IS USM review
(Image: © Future)

Our Verdict

Initial impressions are that the Canon RF 100-400mm f/5.6-8 IS USM is a very capable performer, behaving somewhat similarly to the RF 24-240mm – insofar as it delivers excellent reach and seemingly excellent image quality. And, thanks to the high-ISO performance of the EOS R cameras, that f/8 aperture isn't the hindrance you might expect. Like the RF 100-500, we suspect that AF will be notably better on the R5 and R6 (and the R3), but with a $649.99 / £699 / AU$1,379 price tag this is an almost irresistible telephoto lens.

For

  • Very compact
  • Max 6 stops of IS
  • Affordable

Against

  • f/5.6-8 isn't very fast
  • No weather sealing
  • Will AF keep up on R/RP?

The Canon RF 100-400mm f/5.6-8 IS USM offers a slightly slower, but a lot smaller, lighter, and cheaper alternative to the excellent Canon RF 100-500mm f/4.5-7.1 IS USM lens. 

Despite being launched alongside the formidable Canon EOS R3 (and the Canon RF 16mm f/2.8 STM) this isn't a professional L-series lens, but instead brings a similar degree of telephoto reach to non-pro shooters – and in a more compact form factor that's a better fit for smaller bodies like the Canon EOS R6, with which it pairs well.

The price is definitely a key factor with this optic; it's no secret that RF lenses haven't come cheap until recently, as Canon initially focused on premium-grade glass to show what the EOS R system can do, with only seven of the twenty-three RF lenses coming in at under a grand.

Obviously the biggest question with this lens lies in its aperture. With a gearbox that only shifts between f/5.6 and f/8, can this really deliver for the sports, wildlife and all-purpose shooters at whom its aimed?

Canon RF 100-400mm f/5.6-8 IS USM: Specifications

Mount: Canon RF
Full frame: Yes
Lens construction: 12 elements in 9 groups
Diaphragm blades: 9
Minimum aperture: f/32 at 100mm, f/45 at 400mm
Closest focusing distance: 0.88m
Maximum magnification: 0.41x
Filter size: 67mm
Weather sealed: No
Stabilization: Yes, 5.5 stops (6 stops with IBIS bodies)
Control ring: Yes
Electronic contacts: Yes
Dimensions: 79.5 x 164.7mm (247mm when extended to 400mm)
Weight: 635g

(Image credit: Future)

Canon RF 100-400mm f/5.6-8 IS USM: First impressions

The RF 100-400mm f5.6-8 IS USM is remarkably small, especially when compared to the Canon EF 100-400mm f/4.5-5.6L IS II USM DSLR lens. Its footprint is about 28% smaller, and it's a little over a kilogram lighter, though the variable aperture range is a little more restrictive than the EF lens.

The new compact RF lens doesn't get Canon's prestigious L-series treatment, so it doesn't feature full weather-sealing or a rubber seal around the lens mount to keep water and dust out. That said, it is an unquestionably light, small and feature-dense optic and when paired to one of Canon's equally portable EOS R mirrorless cameras and you have a very compact and capable system.

The 4x optical zoom takes you from short telephoto 100mm f/5.6 zooming all the way into 400mm where the aperture closes down to f/8. Also built-in is Optical Image Stabilization, which Canon claims will enable you shoot at shutter speeds 5.5 stops slower than usually required to eliminate camera-shake from handholding. 

The lens can also be used in tandem with the in-body stabilization of the Canon EOS R5, R6 and R3, with Canon claiming that this takes you to a 6-stop advantage. 

(Image credit: Future)

The telephoto lens is constructed from 12 elements arranged in 9 groups and the aperture has a 9-blade design, so should deliver smooth circular bokeh in out-of-focus highlights. At its widest focal length the lens measures just 164.7mm, and extends to 247mm when zoomed to the maximum 400mm focal length.

There is a lens lock on the barrel that can be set to stop the barrel creeping forward at the 100mm mark. This is useful when you're stowing the lens away to travel – though it would have been nice to be able to lock it into focal lengths such as 135mm, 200mm, 400mm and so on, if you intend to shoot at a specific focal length for long periods.

Also on the side of the lens you'll find switches for auto / manual focus, and another switch to engage or disengage the Optical Image Stabilization. There are also large and grippy zoom and focus rings, with a ridge in the zoom ring that makes it easy to find and turn when looking through the viewfinder. 

There's also the RF Control Ring closest to the front element that, after setting up in the camera menu, can be used to quickly change shutter speed, lens aperture, ISO or Exposure Compensation. 

(Image credit: Future)

Canon RF 100-400mm f/5.6-8 IS USM: Early verdict

We only had the chance to shoot a few samples in less-than-ideal indoor conditions, so we'll have to save proper impressions for when we get a sample to test properly out in the field. 

Initial impressions, though, are that the Canon RF 100-400mm f/5.6-8 IS USM is a very capable performer that behaves somewhat similarly to the Canon RF 24-240mm f/4-6.3 IS USM, insofar as it delivers excellent reach and seemingly excellent image quality. And, thanks to the impressive high-ISO performance of the EOS R cameras, that slow f/8 aperture isn't the hindrance you might expect.

Like the RF 100-500 before it, we suspect that AF performance will be notably superior on the R5 and R6 (and the R3), but with a $649.99 / £699 / AU$1,379 price tag this is an almost irresistible telephoto lens that democratizes long-range shooting with Canon glass. 

Read more:

Best Canon RF lenses
Best Canon telephoto lenses
Canon RF 100-500mm f/4.5-7.1 IS USM review
Hands on: Canon RF 16mm f/2.8 STM review
Canon EOS R review
Canon EOS RP review
Hands on: Canon EOS R3 review
Canon EOS R5 review
Canon EOS R6 review

Dan Mold

The Technique Editor on PhotoPlus: The Canon Magazine, Dan also brings his technical wizardry and editing skills to Digital Camera World. He has been writing about all aspects of photography for over 8 years, having previously served as technical writer and technical editor on Practical Photography magazine, as well as Photoshop editor on Digital Photo


Indeed, Dan is an Adobe-certified Photoshop guru, making him officially a beast at post-processing – so he’s the perfect person to share tips and tricks both in-camera and in post. Able to shoot all genres, Dan provides news, techniques and tutorials on everything from portraits and landscapes to macro and wildlife, helping photographers get the most out of their cameras, lenses, filters, lighting, tripods and, of course, editing software.