Reviews |Canon RF 100-400mm F5.6-8 IS USM First Impressions Review

Canon RF 100-400mm F5.6-8 IS USM First Impressions Review

Best Canon EOS R camera

Price when reviewed


$649.99 / €799.99
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Our Verdict

Canon has been developing its RF lens range at a steady pace and it’s good to see that it is considering the needs of enthusiast photographers as well as professionals. The RF 400mm F2.8L IS USM, which is aimed squarely at pro wildlife photographers, retails for £12,440/$11,999 and the RF 100-500mm F4.5-7.1 L IS USM costs £2,979 / $2,799, putting both beyond the reach of most enthusiasts, but the RF 100-400mm F5.6-8 IS USM could be a viable alternative. It’s also lighter and more manageable than a faster comparable lens.


  • Affordable
  • Compact and lightweight for the focal length


  • Maximum aperture f/8 at 400mm

What is the Canon RF 100-400mm F5.6-8 IS USM

Canon has introduced the RF 100-400mm F5.6-8 IS USM for enthusiast sports and wildlife photographers. It’s designed with portability, low weight and affordability in mind. That means is has a relatively small maximum aperture and no weather-sealing, but it’s stabilised and has a dedicated control ring.

The Canon RF 100-400mm F5.6-8 IS USM is available to pre-order from Adorama in the USA.


  • Product type: Telephoto zoom lens
  • Mount: Canon RF
  • Format: Full-frame
  • Focal length: 100-400mm
  • Maximum aperture: 100mm: f/5.6, 400mm f/8
  • Minimum aperture: 100mm: f/32, 400mm: f/45
  • Construction: 12 elements in 9 groups with 1 UD (ultra-low dispersion) element and 1 PMo (plastic-moulded) aspherical element
  • Coatings: Supra Spectra
  • Focusing system: Nano USM
  • Minimum focus distance: 0.88m
  • Maximum Magnification: 0.41x
  • Stabilisation: Up to 5.5EV alone or 6EV with IBIS
  • Number of diaphragm blades: 9
  • Filter size: 67mm
  • Compatible teleconverters: Extender RF 1.4x and Extender RF 2x
  • Weight: 635g
  • Diameter x length (extension from lens mount): 79.5 x 164.7mm


The Canon RF 100-400mm F5.6-8 IS USM is constructed from 12 elements in 9 groups with one UD (ultra-low dispersion) element and one PMo (plastic-moulded) aspherical element. These special elements correct chromatic and other aberrations while Canon’s Super Spectra coating helps keep flare and ghosting at bay.

Focusing is handled by a Nano USM (ultra-sonic motor), which combines the speed of a ring-type USM system with the low noise and smoothness of STM focusing.

Impressively, the RF 100-400mm F5.6-8 IS USM has a minimum focusing distance of 0.88m (88cm) throughout its focal length range and its maximum reproduction ratio is 0.41x.

Canon has included a stabilisation system within the lens and it’s said to enable shutter speeds of up to 5.5EV slower than normal to be used when the camera is handheld. When the RF 100-400mm F5.6-8 IS USM is mounted on a Canon R-series camera with in-body image stabilisation (IBIS), the shutter speed compensation is claimed to rise to 6EV. At 400mm, that could mean using a shutter speed of just 1/6sec rather than 1/400sec.

At the 100mm end, the RF 100-400mm F5.6-8 IS USM has a maximum aperture of f/5.6, while at 400mm it’s f/8. That may sound slow for a telephoto lens that is likely to be used to capture moving subjects, but the advancements made in noise control make it more acceptable than it used to be.

The RF 100-400mm F5.6-8 IS USM is the first non-L series lens to be compatible with Canon’s RF 1.4x and RF 2x tele extenders, enabling the focal length range to be taken to 140-560mm or 200-800mm respectively.

Build and handling

While it’s not weather-sealed, the Canon RF 100-400mm F5.6-8 IS USM feels well-made with the focusing and zoom rings moving smoothly.

Its low weight (635g) will appeal to anyone who wants to carry the lens over a long distance, but it’s even more attractive when you start shooting. It means that you can use the camera and lens hand-held, but if you decided to mount the camera on a tripod, you won’t be fighting to keep it level on the head as it’s better balanced than an heavier optic.

It’s natural to place a supporting hand under the lens while you look through the viewfinder when the camera is hand-held and the relatively low weight of the optic means that you’re arm won’t tire quickly.

It’s good to see a dedicated control ring on the RF 100-400mm F5.6-8 IS USM. This gives an alternative means of adjusting the shutter speed, aperture, ISO or exposure compensation.

There’s no focus limiter switch on the Canon RF 100-400mm F5.6-8 IS USM, but there are switches on the left of the barrel to turn the image stabilisation on or off and to switch between manual and automatic focusing. Over on the opposite side of the lens, there’s a zoom lock that may be appreciated when the lens is on a camera being carried on a strap.


I’ve been able to handle and shoot with a pre-production sample of the RF 100-400mm F5.6-8 IS USM but I wasn’t allowed to keep or publish any images captured with it. However, on the Canon R6, it focused quickly and unlike with the Canon RF 800mm F11 IS STM and RF 600mm F11 IS STM, the focus area isn’t limited to a square around the centre of the frame.

Vignetting doesn’t appear to be a significant issue but we’ll have to wait for a production sample to see how the lens really performs.

The Canon RF 100-400mm F5.6-8 IS USM is available to pre-order from Adorama in the USA.