Canon EF 50mm f/1.8 STM Lens Review

# EF 50mm f/1.8 STM Lens Review – Gary Wolstenholme reviews the new Canon EF 50mm f/1.8 STM lens, which is designed to offer smoother, quieter autofocus performance.

This lens is an update to the popular and inexpensive standard 50mm f/1.8 EF lens, replacing the standard focusing motor with Canon’s new stepping motor technology, which promises smoother, quieter autofocus performance, which is especially suited to recording video. Although this lens costs more than it’s predecessor, it’s still affordable, costing around £120. In this review, we’ll take a look at how it performs.

In contrast to the previous version of this lens, build quality is good, with high quality plastics used for the lens barrel and a metal bayonet. Despite the higher build quality, this optic still only weighs 160g. The lens balances well with the Canon EOS 5D MkIII body used for testing.

Autofocus is virtually silent, although it can be a little slow when compared to many other Canon lenses. Unlike many of Canon’s USM lenses, full time manual focus override is not possible and manual focusing is performed by the focusing motor. Manual adjustments can be made in single focus mode once the lens has locked onto a target though. The manual focusing ring is well enough damped to prevent the focus ring rotating freely, which makes applying fine adjustments a pleasure. A small switch on the side of the lens allows switching between manual and autofocus quickly.

Focusing is not performed internally, extending by around a centimetre at closest focus. Even so, the 49mm filter thread doesn’t rotate, making this lens ideal for use with polarising and graduated filters.

At maximum aperture sharpness is already very good in the centre of the frame, with the clarity towards the edges of the frame falling just below fairly good levels. Stopping down improves sharpness across the frame, with peak performance being achieved at f/8. Here clarity is excellent across the frame.

Chromatic aberrations are reasonably well controlled, remaining well below one pixel width at all aperture settings. This low level of fringing should be difficult to spot, even in harsh crops from the edges of the frame.

Falloff of illumination towards the edges of the frame is quite strong at maximum aperture, with the corners of the frame being 2.6 stops darker than the centre. Visually uniform illumination is achieved with the aperture stopped down to f/5.6 or beyond.

Distortion is quite strong for a 50mm lens with Imatest detecting 1.89% barrel distortion. If straight lines are paramount, then you’ll be glad to hear that the distortion pattern is uniform across the frame, which should make corrections straightforward to apply.

No issues with flare were encountered during testing, with only a slight loss of contrast being noticeable when shooting directly into the light at wide apertures. However, no lens hood is supplied as standard, so if you require one for peace of mind, then an ES-68 hood can set you back up to £20.

Currently, this lens is available for around £120, which seems quite reasonable, especially as ‘s equivalent 50mm f/1.8 currently costs around £135.

Canon’s old ‘Nifty Fifty’ was a popular lens despite its poor build quality as it represented such good value for money. Even though this lens costs more than its predecessor, it still represents great value due to the high levels of sharpness it produces. The improved build quality is welcome too and should win over many fans as a result.

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column.

Chromatic aberration is the lens’ inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

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