Canon EF 40mm f/2.8 STM

Canon EF 40mm f/2.8 STM

This review covers


» Image Quality «


» Sample Pictures «

» Conclusion «

» Further Information «

Table of contents

Shot with the Canon EF 40mm f/2.8 STM:

Wild blossom  (40mm / 64mm eff., f/5.6, 1/100s, ISO 100, APS-C)  © Gil De Sousa



EF 40mm
f/2.8 STM

Canon's first-ever "pancake" EF lens is a real treat. It's so small that it looks like a 20 mm extension ring rather than a lens and yet it feels solid as a rock and delivers very respectable image quality. It comes with Canon's stepping motor technology (STM) that allows continuous AF during video recording or live-view mode (when used with a hybrid CMOS AF system) and that gives the lens a fast, silent and accurate autofocus performance. The EF 40mm f/2.8 STM is best used for street and travel photography but can also make great portraits (or - as can be seen from my sample pictures - to photograph nature). Its maximum aperture of f/2.8 is great but not really good enough for available light photography (which requires even lower f-stops) and I would have loved to have an image stabilizer - but of course that would have been very difficult to build into a 2.7 " x 0.9 " lens.

In regard to image quality the EF 40mm f/2.8 STM is really a high-end lens. The difference is most apparent if you compare it to a zoom lens but also amongst prime lenses of similar focal length the EF 40mm f/2.8 STM is a high performer. The resolution is great straight from f/2.8 both in the image center and corners. If you use a fullframe camera the EF 50mm f/1.4 USM is a little sharper and the EF 50mm f/1.8 II is about as sharp as the EF 40mm f/2.8 STM (compared at the same aperture). But if you shoot with an APS-C camera the EF 40mm f/2.8 STM easily outperforms both of those lenses (apparently it can cope better with the usually higher pixel density of APS-C cameras). It is roughly as sharp as the APS-C-only EF-S 60mm f/2.8 Macro USM (which is more than 3 times its size).

While the EF 40mm f/2.8 STM shows only very little distortion it does express some serious curvature of the focal plane on a fullframe camera (none on an APS-C cam) but whether that's really visible in an actual image depends a lot on the subject you are shooting and the aperture you are using. Color fringes in focused parts of the image are noticeable and so are the ones that occur in out-of-focus parts of the image. On the good side, the nicely shaped aperture creates evenly smooth background blur but if you are bothered by corner shadows be aware that the EF 40mm f/2.8 STM shows quite intense shadows up to about f/5.6 (with fullframe cameras).

Overall the image quality is quite astonishing for a lens that's as small as the EF 40mm f/2.8 STM and that comes at such a low price tag. This also means that from now on you can always have a decent f/2.8 prime lens with you that virtually needs no space in your camera bag!

Canon set out to create their first pancake EF lens and they did it the right way - combining great features with an incredibly small size at an acceptable price. I am sure many people will love the lens just for its size and the way it feels but even beyond that the EF 40mm f/2.8 STM has a lot to offer.

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Further Information


-Data table

NameCanon EF 40mm f/2.8 STM
Model year2012
Market price (Germany)€ 239
Market price (USA)$ 199
CompatibilityCompatible with full frame cameras
Lens typePrime (fixed focal length)
Aperture range at shortest focal lengthf/2.8 to f/22
Aperture range at longest focal lengthn.a.
Model No.?
Number of aperture blades7
Aperture blades are circular?Yes
Has image stabilization?No
F-stop gain of image stabilizern.a.
Number of image stabilizer modesn.a.
Allows manual override during autofocus?Yes
Has filter thread?Yes
Filter size52 mm
Officially compatible with extenders?No
Has a metal lens mount?Yes
Weight4 oz
Diameter2.7 "
Length (mount surface to front end)0.9 "
Length - fully extended1.2 "
Length - fully extended with hood?
Shortest focal length40 mm
Longest focal lengthn.a.
Effective shortest focal length on cameras with APS-C sensor64 mm
Effective longest focal length on cameras with APS-C sensorn.a.
Minimum focus distance0.98 '
Maximum magnification0.18 x
Front element rotates when focusing?No
Front element rotates when zooming?n.a.
Extends when focusing?Yes
Extends when zooming?n.a.
Zoom lockable?n.a.
Number of AF ranges1
Number of AF presets0
Length of AF preset recall ringn.a.
Sealed against dust and moisture?No
Seal requires filter to be present?n.a.
Has AF stop switch?Yes
Has AF stop button?No
Has distance indicator?No
Distance information is in EXIF data??
Uses drop-in type filters?No
Drop-in filter sizen.a.
Length of zoom ringn.a.
Length of focus ring0.2 "
Number of lenses6
Number of optical groups4
Lens Hood
Maximum diameter?
Model No.ES-52
Lens Cap
Weight0.3 oz
Length0.2 "
Model No.E-52
Tripod Mount
Maximum diameter?
Model No.?
Case / Pouch
Model No.LP811



Image Quality