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Canon RF 10-20mm f/4 L IS STM Lens Review

With the launch of the Canon RF 10-20mm f/4 L IS STM Lens, Canon is expanding their range of professional ultra wide zooms for the EOS R system. The latest full-frame RF mirrorless lens combines an ultralight, highly portable design, with 5-stop image stabilisation and STM autofocus, which is introduced to an L-series lens for the first time.

Whether you're a working professional or advanced enthusiast, we explore if Canon may have designed the ultimate lens for landscape photography, architecture, interiors and moviemaking with this compact zoom.

Watch our video review of the Canon RF 10-20mm lens

Canon RF 10-20mm Lens key features

All of the primary RF 10-20mm lens features are listed below, which impact how the lens will help steer your creativity when capturing ultra wide angle subjects.

  • Rectilinear design, which maintains straight lines
  • Portable size and a low 570g weight
  • 5-stop image stabilisation, or 6-stops with a compatible Canon mirrorless camera
  • STM (stepper motor) autofocus introduced for the first time in an L-series lens
  • Advanced optical design renders knockout image quality
  • Full-time manual focus override
  • Customisable button and control ring
  • Reduced flare and ghosting from Canon lens coatings
  • Rear gel filter holder
  • Dust and moisture resistant design

Canon RF 10-20mm f/4 L IS STM Lens Review

What are Canon L-Series lenses?

L-Series are Canon's flagship range, designed to deliver the highest quality of all Canon lenses, geared towards advanced enthusiasts and professional creators. The Canon RF 10-20mm f/4L IS STM falls into this category, ensuring it has the right attributes to capture high image quality, resolution and colour accuracy.

Canon RF 10-20mm lens mounted to Canon R5 camera body

What is the Canon RF 10-20mm f/4 Lens used for?

With an ultra wide zoom range and lightweight design, the Canon RF 10-20mm f/4 is an excellent full-frame lens for both photography and videography. These types of focal widths are often used for landscapes, architecture and interiors, and with a rectilinear optical design, any lines in the frame remain straight.

This model also benefits from full time manual focusing, where you may wish to punch in and obtain pinpoint focus on a particular subject within a busy composition, which is advantageous for these genres.

Interior sample image RF 10-20mm

Interior Shot with the R5 and RF 10-20mm lens @14mm. Camera settings: 1/200 sec. f/4.5. ISO 3200

Canon RF 10-20mm f/4 Lens image quality

You can achieve razor sharp results even while handholding due to the RF 10-20mm f/4 lens’ combination of GMo, UD and Super UD glass, state-of-the-art lens coatings and proficient image stabilisation. What’s more the STM autofocus system is virtually silent, delivering smooth video AF and quick acquisition for photography.

When paired with an IBIS-equipped camera body such as the R3 and R5 and R6 mark II to name a few, the combined image stabilisation is rated at 6-stops for rock-steady handheld shooting in challenging lighting conditions.

Smaller and lighter than DSLR equivalent models

Why is the new STM advantageous?

Canon designed the RF 10-20mm lens with a lightweight focus group, allowing for the addition of Stepper Motor technology with a position sensor, seen for the first time in an L-series lens. This provides faster start-up times, with more responsive focus for stills and video.

Benefits of the RF mount

This lens showcases many of the benefits of the Canon RF mount, especially when compared to the EF 11-24mm F/4L USM lens, which is its DSLR counterpart. The RF version is offers is wider and 610g lighter, despite featuring built-in optical image stabilisation.

Additionally, RF lenses provide faster communication between the lens and camera through greater bandwidth, improved image quality, combined body and lens IS, and control via the lens control ring.

Sample exterior Canon RF 10-20mm lens

Beach boardwalk with the R5 and RF 10-20mm lens @20mm. Camera settings: 1/200 sec. f/. ISO 320

Ultra wide RF lens comparison

In order to help you decide which is the best one for your needs, we’ve collated a specs table, which provides a side-by-side comparison between Canon’s ultra wide mirrorless zoom lenses. They all offer a rectilinear design, advanced L-series optics and unique focal ranges for different purposes.


RF 10-20mm f/4 L IS STM

RF 14-35mm F/4L IS USM

RF 15-35mm F/2.8L IS USM





Aperture range

f/4 - f/22

f/4 - f/22

f/2.8 - f/22

Special optics

3 x GMo Aspherical,

3 x UD

1 Super UD

3 x GMo Aspherical,

3 x UD ( 1 element both UD / Aspherical)

3 Aspherical

2 UD elements


STM (stepper motor)

Nano USM motor

Nano USM motor

Image stabilisation

5-stops or 6-stops with dual IBIS

5.5-stops or 7-stops with dual IBIS


Diaphragm blades




Minimum focus distance




Maximum magnification

0.12x (at 20mm)
0.06x ( at 10mm)

0.38 (35mm)

0.21x (35mm)

Filter attachment size

Rear gel



Maximum diameter x length

83.7 x 112mm

84.1 x 99.8mm


88.5 x 126.8mm

Dust and moisture seals




Weight Approx.




If you capture ultra wide subjects, whether real estate and architecture, interiors or landscape photography, the latest ultra wide lens to join the RF range will be of particular interest. It combines a lightweight design with Legendary L-series quality, while introducing Canon’s STM technology for the first time. Results are sharp, with virtually no distortion, and the RF 10-20mm is just at home recording video as it is shooting stills.

Across the river with the R5 and RF 10-20mm lens @20mm. Camera settings: 1/200 sec. f/. ISO 250

Across the river with the R5 and RF 10-20mm lens @20mm. Camera settings: 1/200 sec. f/. ISO 250

Image stabilisation goes from great to even better with an IBIS compatible camera body, and the lens is extremely compact for easy portability in the field. While the aperture is narrower than the 15-35mm f/2.8 trinity lens, it’s perfect for its intended subject matter, as well as being significantly lighter.

Reserve your Canon RF 10-20mm f/4 L IS STM lens now and discover what these characteristics can do to elevate your ultra wide content creation.

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By Nick Dautlich on 11/10/2023

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