Canon RF 50mm f/1.2 L USM Review

Autofocus Performance and Accuracy

Any good prime lens needs to have fast and accurate autofocus, especially one that features a very shallow depth of field. These days, even the most basic lenses offer solid focusing performance under normal conditions – but in challenging situations, top-of-the-line lenses prove their value. This is especially true in low light, or when photographing fast-moving subjects against complex backgrounds.

Thankfully, the Canon RF 50mm f/1.2 is impressive in this regard. In One-Shot AF, images snap into focus almost instantly, and the accuracy is excellent. I was particularly impressed by how well the lens was able to nail the focus of a subject’s eye at f/1.2 when used alongside Pupil Detection autofocus. The lens focuses a bit quicker when you use the focus limiter switch (0.8 meters to infinity) rather than racking focus through the entire range. Lastly, low-light performance is excellent due to the f/1.2 maximum aperture.

When it comes to video, the Ring-USM used on the RF 50mm f/1.2 L isn’t as good as the company’s Nano USM Motor, but it nonetheless offers relatively smooth focus transitions. The sound of focusing is comparatively quiet, but you do hear a slight clicking which is picked up by the camera’s mic. In comparison, the Canon RF 24-105mm f/4L IS USM’s autofocus is both quieter and smoother when shooting videos.

In manual focus, the Canon RF 50mm f/1.2 L offers an impressive performance. The manual focus ring is large and offers what is, to me, ideal resistance and smoothness of adjustments. Note that the Ring-USM found on this lens is a focus-by-wire design, which means that the manual focus ring electronically controls the lens’s focus. When the camera is off, for example, turning the focus ring does not do anything.

Distortion

The Canon RF 50mm f/1.2 L has very low levels of distortion. In the lab, I measure just -0.23% barrel distortion, which is negligible. You won’t need to correct the distortion on this lens in the vast majority of situations. Granted, 50mm prime lenses are not known for having much distortion, but it’s still a welcome result.

Here’s a simulation of -0.23% barrel distortion – I can barely tell it’s there at all:

Vignetting

In uncorrected images, the Canon 50mm f/1.2 L has (unsurprisingly) high levels of vignetting wide open. However, the same can be said of almost all f/1.2 lenses, and it quickly improves as you stop down.  Here’s a full chart of vignetting levels:

The maximum of 2.61 stops is certainly on the higher side of things, but you don’t need to stop down much in order for the vignetting to improve. It’s already pretty negligible by f/2. Also, focusing closely helps more than it does on many lenses. For full-body portrait photography, you’ll see closer to the maximum vignetting numbers here – however, for close-ups and headshots, it will be about midway between the close/infinity values. Considering that we’re dealing with an f/1.2 lens, I’m not too bothered by this performance at all.

Lateral Chromatic Aberration

There is a minimal amount of lateral chromatic aberration on the Canon RF 50mm f/1.2 L. Here’s the chart:

Anything under about one pixel is almost impossible to notice in real-world images, even with chromatic aberration corrections turned off. By comparison, the 50mm f/1.2 L maxes out at just 0.85 pixels of chromatic aberration. This is low enough that you will rarely need to correct lateral CA in the first place, and even if you do, software corrections should remove it without any lingering artifacts.

Sharpness

It is a genuine challenge to design an ultra-fast lens that offers excellent sharpness at its maximum aperture. Users of the older Canon EF 50mm f/1.2 L USM will know that it’s a soft lens at f/1.2 and needs to be stopped down past f/2 for solid sharpness characteristics. The same is true of almost all f/1.2 lenses, and even a majority of f/1.4 lenses. However, most photographers care more about bokeh at these apertures, not sharpness, so the old lenses aren’t exactly bad at what they were meant to do.

Nevertheless, it is obvious that Canon wasn’t going to let the RF 50mm f/1.2 fall behind in sharpness given the importance of this lens in its new lineup. Heading into this review, I was keen to find out if the RF 50mm f/1.2 L USM would meet my high expectations – and the answer is a definite yes. The lens turns in an outstanding performance with excellent levels of detail across the frame, and even f/1.2 is quite sharp in the center and midframes (the general area where your subject is likely to be). Here’s what we measure in the lab:

As you can see above, central sharpness is already very good wide open, and nearly at an excellent level. The image quality in the midframes (near the APS-C corner region of the frame) is also surprisingly good at f/1.2, far better than most options on the market. The farthest corner is worse, but not terrible, and it improves substantially by f/2. The lens’s sweet spot in the center is f/4, while the midframes and corners reach their peak at f/5.6. By this point, it is in the top 5% of the sharpest lenses from corner to corner that we’ve tested at Photography Life.

Bokeh

The quality of bokeh is an essential characteristic of an ultra-wide aperture 50mm prime lens, and the RF 50mm f/1.2 L USM lives up to its hefty price tag in this regard. Specifically, the out-of-focus highlights are beautifully rendered at f/1.2, with smooth discs and a nice circular shape. That circular shape lasts through f/1.6, but the highlights are no longer circular by f/2, and are instead shaped like the aperture blades.

As always with lenses this wide, bokeh in the corners at f/1.2 is not quite as good, with more of a “cats eyes” shape – but the RF 50mm f/1.2 transitions to these corners in a very smooth and natural way compared to other lenses on the market. The RF 50mm f/1.2 L USM also does a beautiful job of rendering a smooth focus transition, with excellent smoothness in both the image foreground and background.

The later “Comparisons” section has specific examples head-to-head against the older EF 50mm f/1.2.

Flare

Flare and ghosting on the RF 50mm f/1.2 are very well-controlled for a lens with such a complicated optical design. At f/1.2 with a bright light source in the corner of the frame, the lens shows a very low amount of flaring artifacts, and no veiling flare to speak of. Stopped down to f/16, the flaring becomes a bit stronger, but it remains well-controlled overall.