Join ePHOTOzine, the friendliest photography community.
Upload photos, chat with photographers, win prizes and much more for free!
The Canon EF 40mm f/2.8 STM is a slim, compact pancake type lens, which is compatible with Canon EF and EF-S camera bodies and costs around £230. A fast f/2.8 aperture should make this lens ideal for taking pictures in reasonably low light conditions and focusing is powered by Canon's new STM focusing motor.
Canon EOS 1Ds MkIII used for testing, the lens only protrudes from the body by around half an inch, which should make it the perfect companion for smaller full frame bodies, such as the EOS 5D series cameras, or even compact entry level models. Here the 1.6x crop factor will result in a field of view equivalent to a short telephoto 64mm lens.
Autofocus is very swift and precise. A feint noise is made by the motor during focusing, which sounds not unlike what robots do in sci-fi films, but it is certainly quiet enough to cause very few issues. Unlike Canon's USM lenses, full time manual override is possible by keeping the shutter button half depressed whilst focusing, rather than just grabbing the focus ring at any time. A thin manual focus ring, which is damped just enough, provides control for this. A small switch on the side of the lens allows switching between manual and autofocus quickly.
Focusing isn't performed internally, but the 52mm filter thread doesn't rotate either, making this lens ideal for use with polarising and graduated filters.
Resolution at 40mm
How to read our charts
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 aberrations are virtually non-existent, remaining under half a pixel width in size at all apertures. This extremely low level of CA, should pose no issues, even in large prints, or harsh crops from the edges of the frame.
Chromatic Aberration at 40mm
How to read our chartsChromatic 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.
Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.
For this review, the lens was tested on a Canon EOS 1Ds Mark III using Imatest.
As is quite common for lenses of this type, falloff of illumination towards the corners is quite pronounced. At f/2.8 the corners of the frame are 2.1 stops darker than the image centre and visually uniform illumination isn't achieved until f/8.
Distortion is well controlled, with Imatest only detecting 0.5% barrelling. This low level of distortion should pose few issues for normal shooting. If absolutely straight lines are paramount, then you'll be glad to hear that the distortion pattern is uniform across the frame, which should make corrections relatively 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.
Canon EF 40mm f/2.8 STM Sample Photos
Sharpness is very good across the frame stopped down | 1/50 sec | f/8.0 | 40.0 mm | ISO 100
Fast apertures can be used without any worries | 1/100 sec | f/2.8 | 40.0 mm | ISO 400
Closest focus is 30cm | 1/160 sec | f/8.0 | 40.0 mm | ISO 100
Vignetting can be quite prominent and doesn't disappear completely until stopped down to f/8 or beyond | 1/100 sec | f/3.5 | 40.0 mm | ISO 400
1/250 sec | f/2.8 | 40.0 mm | ISO 400
1/200 sec | f/13.0 | 40.0 mm | ISO 100
1/160 sec | f/14.0 | 40.0 mm | ISO 100
1/160 sec | f/8.0 | 40.0 mm | ISO 100
Value for MoneyThis lens is fairly unique for Canon cameras and the price of around £230 seems fair considering the optical performance. The Canon EF 40mm f/2.8 STM lens is available from Harrison Cameras.
Canon's EF 50mm f/1.8 lens may be a suitable alternative for those on a budget, especially as it weights about the same. Even though it isn't as compact or as well built as the 40mm lens, it is considerably cheaper at around £90 and has a maximum aperture over a stop faster.
Also, for around the same price, the Canon EF 50mm f/2.5 Macro lens can be picked up. Although this lens is a little bulkier than this 40mm optic, it does allow close focusing and 1:2 magnification.
Canon EF 40mm f/2.8 STM ProsExcellent sharpness
Compact and lightweight
Canon EF 40mm f/2.8 STM ConsNo full time manual focus override
More than double the price of the 50mm f/1.8 (although performance and build probably justify this)
|VALUE FOR MONEY|
Canon EF 40mm f/2.8 STM Specifications
|Angle of View||No Data|
|35mm equivalent||No Data|
|Internal focusing||No Data|
|Min Focus||No Data|
|Box Contents||No Data|