On 14 September 2021, Canon announced the RF100-400mm f/5.6-8 IS USM, a new super telephoto zoom lens for the EOS R system. The lens covers a focal length range of 100mm to 400mm, is equipped with image stabilisation of up to 5.5 shutter speed stops’ equivalent, and is also the first Canon lens of its class to support teleconverters. Providing an affordable super telephoto zoom option alongside the professional grade RF100-500mm f/4.5-7.1L IS USM, it promises to make the joy of creating impactful super telephoto photos accessible to more people.

1) Size and weight: Possibly lighter than your standard zoom lens
2) Versatility: The 100-400mm focal length range
3) Image stabilisation: Up to 5.5 stops’ in-lens, up to 6 stops with In-Body IS
4) Nano USM: Swift focusing for stills, seamless focusing for video
5) Up to 0.41x magnification: Achieve the telephoto macro effect
6) Excellent resolution and contrast
7) Key specifications
8) Sample images

 

Super telephoto reach with the versatility of a zoom lens

Besides the reach necessary for capturing closeups of faraway subjects. telephoto zoom lenses also offer more flexibility to frame subjects by zooming in and out as necessary. No lens lineup is complete without them.

Previously, Canon released three such lenses for the EOS R system:
- RF70-200mm f/2.8L IS USM
- RF70-200mm f/4L IS USM
- RF100-500mm f/4.5-7.1L IS USM

However, these were all professional grade L-series lenses with premium performance and prices to match. The RF100-400mm f/5.6-8 IS USM is Canon’s first non-L series telephoto zoom lens, providing an affordable and versatile super telephoto zoom option alongside the unique RF600mm f/11 IS STM and RF800mm f/11 IS STM super telephoto prime lenses.

 

The size of a 350ml tumbler, and possibly lighter than your standard zoom lens

The RF100-400mm f/5.6-8 IS USM can be considered the RF mount native equivalent of the EF70-300mm f/4-5.6 IS II USM. Why start from 100mm? That’s because the standard zoom lenses in the RF lens lineup, particularly the kit lenses that most users would own, end at 105mm, and the 100mm wide end of the RF mount picks up the baton seamlessly. At the same time, it offers a telephoto end that, at 400mm, is 100mm longer, achieving extra reach that matters a lot.

One would think that the extra reach would add to the body size, but the RF100-400mm f/5.6-8 IS USM is around the size of a 350ml tumbler and weighs only 635g: lighter than the RF24-105mm f/4L IS USM (700g). Achieving reach in a lighter body, while at the same time maintaining excellent image quality, is a feat achievable because of the RF mount.

As the diagram above shows, the EOS R6 and RF100-400mm f/5.6-8 IS USM make a smaller, lighter combination than the EOS 6D Mark II with the EF100-400mm f/4.5-5.6L IS II USM—the difference in weight is more than 1kg! It’s not a fair comparison as the EF100-400mm f/4.5-5.6L IS II USM is a professional grade lens that offers better image quality. However, if portability and mobility are what’s most important, the RF100-400mm f/5.6-8 IS USM offers clear advantages especially combined with the smaller, lighter EOS R mirrorless system. Why not take full advantage of it by bringing it on your hikes, nature walks, or taking it birding?

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 400mm/ Aperture-priority AE (f/8, 1/200 sec)/ ISO 400/ WB: Daylight

 

Various subjects, different compositions: 4x zoom for greater versatility

 

 

Image stabilisation: Up to 5.5 stops with in-lens Optical IS, up to 6 stops combined with camera In-Body IS

Camera shake becomes more obvious the longer the focal length, which makes image stabilisation crucial for telephoto zoom lenses. As a rule of thumb, when shooting handheld, your shutter speed needs to be at least 1/(your focal length) second to avoid camera shake, which means that at 400mm, you should be shooting at 1/400 second or faster.

In situations where you need to bump up the ISO speed to compensate for a faster shutter speed, achieving clean images is no sweat with the excellent high ISO speed performance of the cameras in the EOS R system. But there are also times where you want to avoid using a higher ISO speed, or where a slower shutter speed achieves the picture better. That’s when the maximum 5.5-stop Optical IS (in-lens image stabilisation) comes in handy. Use it with a camera equipped with In-Body IS like the EOS R5 or EOS R6, and the effect goes up to 6 shutter stops’ equivalent, helping you to achieve handheld shots you might not have thought were possible.

EOS R6/ IS OFF/ Shutter speed: 1/6 sec

EOS R6 (Coordinated Control IS: up to 6 stops)/ IS ON/ Shutter speed: 1/6 sec

EOS R (Optical IS: up to 5.5 stops) / IS ON/ Shutter speed: 1/13 sec

 

Nano USM: Swift focusing for stills, seamless focusing for video

The autofocus (AF) on the RF100-400mm f/5.6-8 IS USM is driven by a Nano USM (Ultrasonic Motor), a tiny motor that directly drives the focusing lens group, enabling quick, accurate, and precise control over focusing. This achieves fast, accurate focusing when shooting stills—great for catching unexpected shutter opportunities—and smooth, seamless AF tracking crucial for ensuring high-quality videos.

AF area on the RF100-400mm f/5.6-8 IS USM
EOS R5/R6: approx. 90% × 100% (horizontal × vertical); 100% × 100% during Face Detection + Tracking Priority AF
EOS R/RP: approx. 88% × 100%
With Extender RF 1.4x: approx. 80% × 80%
With Extender RF 2x: approx. 40% × 60% (horizontal × vertical)

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 400mm/ Manual exposure (f/8, 1/800 sec)/ ISO 1600/ WB: Auto

 

Up to 0.41x magnification: Achieve macro-like shots

The RF100-400mm f/5.6-8 IS USM not only draws in faraway objects so that they fill more of the frame, it also can do so for objects that are nearer, achieving a close-up look that resembles a macro image. It has a maximum magnification of up to 0.41x. In other words, the image of the subject projected on the image sensor is 0.41x of its actual size.

The lenses that are specifically designed for close-up shooting (which usually have “Macro” in the lens name) have a maximum magnification of at least 0.5x, so 0.41x is quite strong for a lens that was not designed to be a macro lens. While the closest focusing distance varies depending on the focal length, the 0.41x maximum magnification is achieved at 400mm.

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 400mm/ Aperture-priority AE (f/8, 1/125 sec, EV +0.3)/ ISO 400/ WB: Daylight

 

Excellent resolution and contrast

The lens configuration of the RF100-400mm f/5.6-8 IS USM includes one well-placed UD lens element that corrects chromatic aberration and colour fringing across the entire zoom range. There is also one aspherical lens element, which helps to achieve excellent resolution and contrast.

A: UD lens element
B: Aspherical lens element

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 100mm/ Aperture-priority AE (f/5.6, 1/50 sec)/ ISO 200/ WB: Daylight

 

RF100-400mm f/5.6-8 IS USM

 

Key specifications

Lens construction: 12 elements in 9 groups
Closest focusing distance: 0.88m (at focal length 200mm)
Maximum magnification: 0.41x (at focal length 400mm)
No. of aperture blades: 9
Filter diameter: 67mm
Size: φ79.5 x 164.7mm (retracted）
Weight: approx. 635g

 

Lens hood: ET-74B (sold separately)

 

Sample images

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 400mm/ Shutter-priority AE (f/8, 1/25 sec)/ ISO 1600/ WB: Daylight

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 400mm/ Aperture-priority AE (f/8, 1/500 sec, EV +0.7)/ ISO 100/ WB: Daylight

EOS R6/ RF100-400mm f/5.6-8 IS USM/ FL: 100mm/ Manual exposure (f/5.6, 1/1250 sec)/ ISO 5000/ WB: 3500K

 

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