RF50mm f/1.8 STM vs. RF50mm f/1.2L USM: What’s the Difference?
What are 50mm prime lenses, and what can you do with them? In this article, we share why and introduce two 50mm RF lenses: the RF50mm f/1.8 STM and the RF50mm f/1.2L USM.
Introduction: The attraction of 50mm prime lenses
Introduction: The attraction of 50mm prime lenses
EOS R6 + RF50mm f/1.2L USM @ f/1.2, 1/1600 sec, ISO 200
1. A natural perspective that better captures the human eye sees
50mm lenses are known to have the least visible distortion, which means they capture a natural perspective very similar to what the human eye sees. You won’t have to worry about things at the corners looking strangely stretched, like you might have encountered when taking phone selfies. This makes them easier to work with especially for beginners, regardless of whether you are shooting up close or from further away.
EOS R5 + RF50mm f/1.8 STM @ f/16, 1/2 sec, ISO 12800
2. Easy to compose: Frame scenes close to the way you see them
EOS R3 + RF50mm f/1.8 STM @ f/1.8, 1/60 sec, ISO 12800
When you look in front of you, your central field of view is around 50 to 60 degrees. The 39.6-degree angle of view on a 50mm lens is slightly narrower: enough to easily leave distractions out of the frame and create eye-catching compositions of the scene that fascinates you.
(In reality, the angle of view can also be measured vertically and diagonally. But for easier understanding, we’ve taken the horizontal angle of view as a reference.)
Frame full-body portraits from a comfortable distance away
EOS R5 + RF50mm f/1.2L USM @ f/1.2, 1/160 sec, ISO 640
Examples shot on 50mm lenses
You may be interested in:
50mm Portraits, My Style: Creating A Picture of a Memory
EF50mm f/1.8 STM: A Review with Useful Composition Tips
Canon’s two RF 50mm prime lenses
Canon’s two RF 50mm prime lenses
Canon has two 50mm prime lenses with large maximum apertures that achieve beautiful bokeh. One is the compact and inexpensive RF50mm f/1.8 STM “nifty fifty”. The other is the professional RF50mm f/1.2L USM, a favourite among many professional photographers due to its very large aperture and reliability.
This table shows the key differences between them. Scroll on for more details!
Main differences
RF50mm f/1.8 STM | RF50mm f/1.2L USM | |
Size | Small and compact | Bigger |
Dimensions (approx.) | 69 x 40mm | 89.8 x 108mm |
Weight (approx.) | Approx. 160g | Approx. 950g |
Maximum aperture | f/1.8 | f/1.2 |
Weather sealing | No | Yes |
Quality | Standard | Professional quality |
You may be interested in:
RF50mm f/1.8 STM vs EF50mm f/1.8 STM: 6 Key Comparisons
Lens Impressions: RF50mm f/1.2L USM in Portraits & Street Photography
1. Bokeh
EOS R5 + RF50mm f/1.8 STM @ f/1.8, 1/125 sec, ISO 200
Both lenses are considered “fast lenses” as they have large maximum apertures. This has two advantages:
1. They allow you to use a faster shutter speed and/or lower ISO speed in poorer lighting, which achieves sharper images.
2. They create beautiful bokeh that blurs out the background and/or foreground. You can use this to isolate subjects or achieve a dreamy look!
RF50mm f/1.2L USM at max aperture
RF50mm f/1.8 STM at max aperture
The RF50mm f/1.2L USM has the larger maximum aperture (f/1.2), which achieves more intense bokeh.
Real-world comparison: Different lenses, different bokeh quality
This doesn’t mean that both lenses give the same bokeh quality at f/1.8. Here’s what happened when we stopped down the RF50mm f/1.2L USM to f/1.8.
RF50mm f/1.2L USM at f/1.8
RF50mm f/1.8 STM at f/1.8
Close-up
The bokeh on the L lens looks smoother and creamier. Much engineering effort went into ensuring bokeh quality that would meet the needs of professional photographers.
Difference #2: Impact on bokeh performance
2. AF performance
EOS R6 + RF50mm f/1.2L USM @ f/1.2, 1/160 sec, ISO 3200
The larger the maximum aperture, the easier it is to focus even under challenging conditions. One example is this black dog at night where there is little contrast. A larger maximum aperture allows more light to enter the camera. More light means more information for the autofocus system—and better focusing accuracy!
Difference #3: Weather-sealing and durability
3. Weather-sealing and durability
Like other L-series lenses, the RF50mm f/1.2L USM adopts a dust- and drip-resistant design that prevents dust and moisture from entering the lens. This gives it better reliability and durability when shooting in harsh or unpredictable weather conditions.
It also features oil- and dirt-repellent fluorine coating on the front and rear lens surfaces for easier removal of fingerprints and smudges.
4. Image quality
All lenses have inherent issues that affect image quality. These are corrected in different ways to different degrees on the RF50mm f/1.2L USM and RF50mm f/1.8 STM:
RF50mm f/1.8 STM | RF50mm f/1.2L USM |
A: PMO aspherical lens |
A: Aspherical lens elements B: UD lens elements |
|
|
- Super Spectra Coating - Optimised lens element shapes |
Air Sphere Coating |
|
|
PMo (Plastic Molded) aspherical lens | - 2 x ground aspherical lenses - GMo (Glass Molded) aspherical lens - UD lens |
As a professional grade lens, the RF50mm f/1.2L USM incorporates more special glass to ensure the best possible image quality even under challenging conditions, such as those with the sun in the frame.
What is ghosting and flaring? Learn more in:
Lens FAQ #4: What is “ghosting” and “flaring”?
Real-world comparison: Performance with strong lighting in the frame
RF50mm f/1.2L USM at f/16, 8 sec, ISO 100
RF50mm f/1.8 STM at f/16, 8 sec, ISO 100
No visible ghosting here
Ghosting is visible as a blue-coloured smudge.
Know this: Ghosting and flaring usually occur when there is a strong light source in the frame, although this also depends on the angle at which the light enters the lens.
Difference #5: Controls and switches
5. Controls and switches
The RF50mm f/1.8 STM has a very simple design with just one ring and one Control/Focus switch. The switch changes the function of the ring.
The RF50mm f/1.2L USM has two rings and two switches:
- Focus ring
- Control ring
- AF/MF switch
- Focus limiting switch
You can switch to manual focusing with just a flip of the switch. The focus limiting switch provides more control over the focusing distance.
Difference #6: Closest focusing distance
6. Close-up shooting
The RF50mm f/1.8 STM has a shorter closest focusing distance (30cm) compared to the RF50mm f/1.2L USM (40cm), allowing it to focus on objects that are nearer. The images below, both shot at 50mm, show how this affects your photos. The first close-up image is possible only on the RF50mm f/1.8 STM.
30cm focusing distance
40cm focusing distance
In both images, the lens’ field of view remains the same, but the subject fills more of the frame when the lens is closer to it, as the 30cm focusing distance example shows. Being able to focus close-up is important when photographing food, small objects, or details.
Also see:
Lens FAQ: What Images Can I Get with 0.25x or 0.5x Magnification?
Key specifications: RF50mm f/1.8 STM vs. RF50mm f/1.2L USM
Key specifications: RF50mm f/1.8 STM vs. RF50mm f/1.2L USM
RF50mm f/1.8 STM | RF50mm f/1.2L USM | |
Size | 69.2 x 40.5mm | 89.8 x 108mm |
Weight | 160g | 950g |
Widest aperture | f/1.8 | f/1.2 |
Narrowest aperture | f/22 | f/16 |
Aperture blades | 7 (circular) | 10 (circular) |
Closest focusing distance | 30cm | 40cm |
Maximum magnification ratio | 0.25x | 0.19x |
No. of lens elements and groups | 6 elements in 5 groups | 15 elements in 9 groups |
Special lenses | PMo aspherical lens x 1 | Ground aspherical lenses x 2 GMo aspherical lens x 1 UD lens |
Special coatings | Super Spectra Coating | Fluorine coating ASC (Air Sphere Coating) |
Switches and controls | Combined focus/control ring Control/focus switch |
Control ring Focus ring Focus limiting switch AF/MF switch |
Image stabilizer | No | No |
Mount material | Metal | Metal |
Dust and drip-resistance | No | Yes |
Filter size | 43mm | 77mm |
Which lens will you choose?
Need help deciding on which lens to get next? See:
Prime Lens or Zoom Lens: Which Should I Buy?
10 Concepts to Know Before Buying Your Second Lens