Lens Test: Canon EF 50mm F/1.8 STM

Continuing to upgrade select lenses from its catalog with stepping motors, Canon has added STM focusing capability to its EF 50mm f/1.8 prime. The new motor mates up with the Movie Servo AF mode in newer DSLRs for quicker, smoother, and quieter autofocus for video and live view. The lens also boasts an upgraded lens mount, now metal instead of plastic and a new Super Spectra coating for better control of ghosting and flaring.

Compact and light, with an 80mm equivalent focal length on Canon’s APS-C bodies, the lens is about 1/8-inch shorter than the previous 50mm f/1.8. In fact, it’s Canon’s most compact 50mm ever, and also smaller than the Nikon 50mm f/1.8G (tested in our September 2011 issue), Pentax DA 50mm f/1.8 (February 2013), and Sony 50mm f/1.8 DT (October 2009). It also produces attractive bokeh with superb subject sharpness thanks to a new seven-blade circular aperture. Its predecessor had a five blade diaphragm, non-circular in shape. As a result, defocused specular highlights were not round, but pentagon-shaped.

The manual focus ring on this new lens has been enlarged and slightly repositioned. Previously, it was far forward at the outer rim of the lens and a meager 0.18 inches wide. Now it has almost doubled in size to 0.33 inches and moved closer to the camera body, making it easier to reach while holding the camera. This, plus the STM AF motor, should please both video and manual-focus fans. Canon has also given the lens a cosmetic upgrade with simpler markings and an attractive matte black finish.

In the field, the new 50mm provided consistently quiet and fast autofocus, a bright viewfinder image, and a smooth manual focus action. Despite its many improvements, the lens sells for a price that belies its excellent imaging capabilities: $125, street.

On our lens bench, Canon’s new 50mm produced Excellent-range SQF scores, slightly better than the earlier version, especially at maximum aperture, reaching an A rating, up from B+. Distortion tests using DxO Analyzer 5.3 showed Slight barrel distortion (0.20%), very much improved from the older lens, which produced Very Visible 1.1% barreling. Pentax showed the class-leading distortion control with Imper­ceptible-range barreling of 0.06%.

This new lens showed no edge falloff from f/2.8 compared with f/4 of the previous version. The close focusing distance for the new and previous versions, plus the Sony, were all similar. The new Canon, however, focused closer than either the Nikon (by 3.13 inches) or the Pentax (by 3.63 inches). Subject magnification at 1:4.32 was also improved over the earlier lens’s weaker 1:6.3.

This timeless entry-level prime is a nice fit for portrait, active, and low-light subjects. While the price of most 50mm f/1.8 lenses is low, the new Canon costs about $50 less than the comparable Nikon. Between test results that showed improvement by almost every optical metric and Canon’s numerous small but significant handling and cosmetic upgrades, this lens is undeniably a winner and a welcome addition to the Canon lens catalog.

Continuing to upgrade select lenses from its catalog with stepping motors, Canon has added STM focusing capability to its EF 50mm f/1.8 prime. The new motor mates up with the Movie Servo AF mode in newer DSLRs for quicker, smoother, and quieter autofocus for video and live view. The lens also boasts an upgraded lens mount, now metal instead of plastic and a new Super Spectra coating for better control of ghosting and flaring.

Compact and light, with an 80mm equivalent focal length on Canon’s APS-C bodies, the lens is about 1/8-inch shorter than the previous 50mm f/1.8. In fact, it’s Canon’s most compact 50mm ever, and also smaller than the Nikon 50mm f/1.8G (tested in our September 2011 issue), Pentax DA 50mm f/1.8 (February 2013), and Sony 50mm f/1.8 DT (October 2009). It also produces attractive bokeh with superb subject sharpness thanks to a new seven-blade circular aperture. Its predecessor had a five blade diaphragm, non-circular in shape. As a result, defocused specular highlights were not round, but pentagon-shaped.

The manual focus ring on this new lens has been enlarged and slightly repositioned. Previously, it was far forward at the outer rim of the lens and a meager 0.18 inches wide. Now it has almost doubled in size to 0.33 inches and moved closer to the camera body, making it easier to reach while holding the camera. This, plus the STM AF motor, should please both video and manual-focus fans. Canon has also given the lens a cosmetic upgrade with simpler markings and an attractive matte black finish.

In the field, the new 50mm provided consistently quiet and fast autofocus, a bright viewfinder image, and a smooth manual focus action. Despite its many improvements, the lens sells for a price that belies its excellent imaging capabilities: $125, street.

On our lens bench, Canon’s new 50mm produced Excellent-range SQF scores, slightly better than the earlier version, especially at maximum aperture, reaching an A rating, up from B+. Distortion tests using DxO Analyzer 5.3 showed Slight barrel distortion (0.20%), very much improved from the older lens, which produced Very Visible 1.1% barreling. Pentax showed the class-leading distortion control with Imper­ceptible-range barreling of 0.06%.

This new lens showed no edge falloff from f/2.8 compared with f/4 of the previous version. The close focusing distance for the new and previous versions, plus the Sony, were all similar. The new Canon, however, focused closer than either the Nikon (by 3.13 inches) or the Pentax (by 3.63 inches). Subject magnification at 1:4.32 was also improved over the earlier lens’s weaker 1:6.3.

This timeless entry-level prime is a nice fit for portrait, active, and low-light subjects. While the price of most 50mm f/1.8 lenses is low, the new Canon costs about $50 less than the comparable Nikon. Between test results that showed improvement by almost every optical metric and Canon’s numerous small but significant handling and cosmetic upgrades, this lens is undeniably a winner and a welcome addition to the Canon lens catalog.

What’s hot Stepping motor for better video focusing

What’s not No depth-of-field scale

Who it’s for
Shooters wanting the look of a normal lens with better video functionality

SPECIFICATIONS 50mm (51.39mm tested), f/1.8 (f/1.89 tested), 6 elements in 5 groups. Focus ring turns 180 degrees. Diagonal view angle: 46 degrees Weight: 0.35 lb filter size: 49mm Mounts: Canon AF Street price: $125 Website: canonusa.com

TEST RESULTS Distortion: 0.20% (Slight) barrel Light falloff: Gone by f/2.8 Close-focusing distance: 13.37 inches Maximum magnification ratio: 1:4.32