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

Difference #1: Bokeh

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!

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.

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

Difference #4: Image quality

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
Reduce ghosting and flaring
- Super Spectra Coating - Optimised lens element shapes	Air Sphere Coating
Correct colour fringing, improve sharpness, etc
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

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

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.

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

 

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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