The Canon RF 20mm f/1.4L VCM is an intriguing lens for photographers who want a wide field of view without sacrificing aperture. Its f/1.4 maximum aperture makes it particularly appealing for astrophotography, while the 20mm focal length offers plenty of room for landscapes, architecture and other wide-view scenes.
We took the lens out to the dark skies of Wales to photograph the night sky and the Perseids, giving it a real-world test in some of the best conditions we could find.
With a premium L-series build and a price tag to match, there’s a lot to consider before adding this lens to your kit. We wanted to find out how it actually performs in the real world, and whether it’s worth the investment.
Canon RF 20mm f/1.4L VCM: Design
It’s a nice size and weight, despite not being the smallest lens.
(Image credit: Kimberley Lane)
- Premium, solid build
- Surprisingly manageable for an f/1.4 lens
- A few small quirks keep it from being flawless
The Canon RF 20mm f/1.4L VCM feels like a proper L-series lens from the moment you pick it up. It’s solid and reassuringly well-built, but it never felt excessively heavy or awkward on the camera. At 1.41 pounds (519 grams), it’s certainly not a tiny 20mm prime, but the weight is well balanced and it was comfortable to carry and shoot with. And considering it’ll often be used for astrophotography, it’ll be on a tripod a lot of the time anyway.
The focus and control rings both feel smooth and nicely weighted, while the switches and customizable buttons are easy to find without having to look at the lens. The weather-resistant build is another bonus for outdoor shooting, which will come in handy if you also use the lens for landscapes where you might encounter inclement weather.
The dedicated aperture ring is also a nice feature, especially if you prefer having more physical controls rather than relying on the camera body and remembering which dial is set to each setting. Plus, the clickable nature of the aperture ring is an ASMR dream.
Canon RF 20mm f/1.4L VCM: Performance
The wide 20mm focal length and fast f/1.4 aperture are perfect for astrophotography.
(Image credit: Kimberley Lane)
- Excellent low-light performance
- Sharp in the center with some corner softness
- f/1.4 makes a real difference under dark skies
A fast 20mm is a pretty exciting combination for astrophotography. It gives us plenty of sky to play with, while the f/1.4 aperture pulls in a lot of light. Under those dark skies, the Milky Way came through beautifully, with plenty of detail without needing to resort to boosting the ISO too high.
We took the lens out to Carmarthenshire in Wales under Bortle 3 skies to photograph the night sky during the peak of the Perseids, which also coincided with the new moon — the perfect recipe for astrophotography.
The center of the frame is where this lens is at its best. Stars are crisp and well-defined, which is exactly what we want from a lens that is being used for astrophotography. The edges aren’t quite as impressive, though. There is some softness and a little stretching of the stars towards the outer parts of the frame, particularly when the lens is wide open. It’s not enough to ruin an image, but it becomes obvious when zooming in and pixel-peeping at the corners.
Canon RF 20mm f/1.4L VCM: Functionality
(Image credit: Kimberley Lane)
- Quick and reliable autofocus performance
- Customizable controls are genuinely useful
- A practical choice for everyday shooting
The Canon RF 20mm f/1.4L VCM is very straightforward to use out in the field — especially in the dark. The autofocus was quick and reliable during testing, and for everyday shooting of landscapes, or even for video, this means there’s very little to think about.
The customizable controls are useful, too. The lens function button and control ring can be assigned to different settings, allowing you to put the controls you use most within easy reach. It’s a small thing, but being able to set the lens up around your personal shooting style makes it feel more intuitive and can save a surprising amount of time.
Key specifications:
Focal length: 20mm
Aperture: Constant f/1.4
Weight: 1.14 pounds (519 g)
Dimensions: 3 x 3.9 inches (76.5 x 99.3 mm)
Filter thread: 67 mm
The 67mm filter thread is another practical advantage, as it’s a common filter size, so you won’t necessarily need to invest in an entirely new set of filters if you already own that size.
The lens doesn’t feature a ton of bells and whistles, but that’s not a bad thing. It’s designed to be picked up and used without much fuss, and after spending time with it, we found that its simplicity is one of its strengths.
Should you buy the Canon RF 20mm f/1.4L VCM?
The Canon RF 20mm f/1.4L VCM lens makes the most sense for photographers who regularly work in low light or want a dedicated wide-angle prime. Astrophotographers are likely to get the most from it, but it also has plenty to offer for landscapes, architecture, interiors and environmental photography.
Its biggest appeal over a zoom is its f/1.4 aperture. If you already have a wide-angle zoom but regularly find yourself having to bump up your ISO in low light, this lens fills that gap while also offering the control of a fast prime.
However, it’s a fairly specialist addition to a lens lineup, and the price makes it tricky to justify if you only occasionally shoot wide. If you need the flexibility of changing focal lengths, or if you primarily shoot distant subjects, you’d be served better by a zoom or longer lens
If this lens isn’t for you
The Canon RF 16mm f/2.8 STM is a much more affordable way into Canon’s full-frame RF wide angle range, and it’s much smaller and lighter. It lacks the 20mm f/1.4L’s fast aperture, L-series glass and premium build, but if you’re just starting out, or you only occasionally shoot wide, it could be a better option.
If 20mm isn’t wide enough, the Canon RF 14mm f/1.4L VCM gives a noticeably more expansive view while keeping the same fast f/1.4 aperture. It’s a slightly more specialist choice for dedicated astrophotographers who want to capture as much sky or landscape as possible.
Canon RF 15-35mm F2.8L IS USM
If you don’t want to be stuck with one focal length, the Canon 15-35mm f/2.8L IS USM is the obvious choice for astrophotographers. The focal range covers a much wider variety of photography styles, making it more practical for everyday shooting.
