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Conclusion - Pros

  • Very good optics
  • Tiny size
  • Silent autofocus
  • Responsive electronic manual focus
  • Decent construction
  • Low price

Conclusion - Cons

  • Can be susceptible to flare
  • No lens hood supplied
  • AF speed isn't the fastest

Overall conclusion

The EF 40mm f/2.8 STM is a fairly unprepossessing little lens, and its tiny size and relatively low price might make you wonder whether significant compromises have been made in its design and construction. But the moment you start shooting with it and looking at the images it produces, any such thoughts rapidly disappear - it's actually a very fine lens. The main trade-off against other primes is its relatively slow maximum aperture, but that's really a function of its size, and the resultant diminutive dimensions mean that it's a lens you can carry around with you all the time and barely notice.

Optics and image quality

Optically, there's very little to complain about in our studio tests; the 40mm is impressively sharp wide open, and very sharp right across the frame at normal working apertures (F5.6 - F11). Chromatic aberration and distortion are both very low too. About the only possible criticism is vignetting wide open on full frame, which measures 1.7 stops, and is more than you'll see when shooting faster lenses at F2.8. But the broad falloff profile means it's not often objectionable in real-world use, and it's trivial to correct in post-processing when necessary. All Canon SLRs made in the last 5 years or so can correct it automatically in their JPEG processing too, if you desire.

Moving on the real-world use, the 40mm continues to impress. It gives consistently fine results on both full frame and APS-C cameras, with an attractive rendition of out-of-focus ares of the image. Its rather exposed front element means that it can be somewhat susceptible to flare in bright conditions, so that's something to look out for while shooting. Sadly Canon refuses to supply a hood with the 40mm, but you can use a generic 52mm screw-in hood to combat stray light in bright conditions.

Autofocus and manual focus

Autofocus performance is fine - it's not super-fast, probably because the entire optical unit moves back and forward for focusing, but it is very smooth and quiet. The electronically-driven manual focus works very well too, and arguably rather better than the relatively loose mechanically-coupled mechanisms found on many other inexpensive lenses such as the EF 50mm f/1.8 II. One thing to be aware of, though, is that the focus can't be adjusted when the lens is removed from the camera. This means it's entirely possible to find yourself putting the lens in your bag with the optical unit protruding 8mm out of the barrel, making it more vulnerable to damage (and reducing the size advantage too).

One attraction of the STM focus motor is the ability to refocus smoothly and silently during movie recording - which Canon makes particularly easy to control on its latest touchscreen SLRs. The 40mm delivers on this promise only partially - it's extremely quiet, but refocusing during recording isn't quite as decisive as Canon's latest kit zoom, the EF-S 18-55mm f/3.5-5.6 IS STM (click here for an example with this lens). In particular the lens's relatively slow autofocus can make the contrast-detect focus confirmation step of Canon's hybrid system a little more obvious, resulting in a visible 'wobble' around the point of focus.

Some people may well question the lens's focal length: 40mm is a relatively unfamiliar number on full frame, as is the 64mm-equivalent it offers on APS-C SLRs. We struggle to see it as an ideal focal length on APS-C for general purpose photography, and certainly wouldn't recommend it as the only lens to own; it's best used to complement a kit zoom. But the short telephoto effect can be useful for head-and-shoulder portraits, and the larger aperture compared to kit zoom offers better background blur and low-light performance.

On full frame, though, we're of the camp that sees 40mm as an excellent general purpose option, and close to the ideal 'normal' lens. It's a great pairing with cameras like the EOS 6D and 5D series, whose low-light performance goes a long way to negating any perceived disadvantage of the 'slow' maximum aperture (for a prime). It's never going to be the first choice if you want a lens to give shallow depth of field and highly-blurred backgrounds, though.

The big question, perhaps, is how it compares to the older EF 50mm f/1.8 II and EF 35mm f/2 primes, or the more expensive EF 50mm f/1.4 USM. Our studio tests reveal that there's little to choose between them optically, with all performing very similarly across the shared aperture range. To an extent, this helps to narrow the choice down to size, price and features. If size is your priority and you don't need a faster aperture, then the 40mm is the obvious choice. If you're looking to experiment with selective focusing and shallow depth of field, one of the 50mm lenses would be a better bet (however the 50mm F1.8's 5-bladed diaphragm results in distracting pentagonal out-of-focus highlights when it's stopped down a bit).

The Final Word

The EF 40mm f/2.8 STM is a lens whose impressive image quality belies its low price and tiny size. For APS-C users it's a tiny, inexpensive companion to a kit zoom, and on full frame it offers a great option for general shooting. It's also nicely built, and on the whole the STM focusing works pretty well. Compact pancake primes have undergone something of a revival in recent years, with such gems as the Panasonic Lumix G 20mm F1.7 ASPH and Samsung NX 30mm F2 Pancake showing that small size doesn't necessarily have to mean compromised quality. It's taken a while for Canon to come to the party, but the 40mm takes its place alongside its peers as one of the best examples of its type.

Canon EF 40mm f/2.8 STM
Category: Normal Lens
Optical Quality
Build Quality
Ergonomics and Handling
Good for
Canon SLR owners who want the image quality of a prime in a tiny, relatively inexpensive package.
Not so good for
Photographers shooting in really low light or aiming for maximum background blur. They'll do better with a faster lens like the EF 50mm F1.8 II.
Overall score
The EF 40mm F2.8 STM offers excellent image quality in a tiny, well-made package. For APS-C users it provides a great carry-everywhere complement to a kit zoom, and for full frame shooters it's an excellent general-purpose 'normal' lens. The STM motor means that autofocus is almost completely silent, but it's not super-fast.

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There are 30 images in the review samples gallery and 31 images in the preview samples gallery. Please do not reproduce any of these images on a website or any newsletter / magazine without prior permission (see our copyright page). We make the originals available for private users to download to their own machines for personal examination or printing (in conjunction with this review), we do so in good faith, please don't abuse it.

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Canon EF 40mm f/2.8 STM review samples

30 images • Posted on Jun 12, 2013 • View album
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Total comments: 15
Peter Kellogg

Why doesn't Canon make an "L" version of this lens? I like the sample images, but there's no way its got the same quality as the professional lenses. And the focal length is perfect for street photography...

1 upvote

It's got surprisingly good quality, you might not be able to tell the diff. Been using it since it came out.


It is actually as sharp if not sharper than the old 35mm L.
I was quite surprised by the picture quality this ridiculously small and unimpressive piece of plastic actually delivers.
Most certainly, it is not for whale watching or deep space astronomy but a very decent replacement for a 24-70 zoom that you just sent for repairs.

Comment edited 2 minutes after posting
Sad Joe

PLUS: That its such a stunning little lens with STM motor. CONS: That Canon have totally FAILED to follow it up with any other decent PRIME STM lenses - SHAME ON YOU CANON.


That is not a CON as far as the lens is concerned, is it. Does the lack of new prime lenses from Canon make this lens perform any worse?


Reviewer overlooked the 1969 GN-45mm f/2.8 Nikkor in recounting the history of these pancake normal primes. GN stands for 'guide number' which references the output of a flash unit or flash bulb -- important in the days of manual flash calculations. On this lens, the user would set the guide number, and the lens then adjusted the aperture from 2.8 to 32 according to the focused distance. Pretty cool, eh?


Too bad this review was written before the new 35mm f/2 IS USM was released. It seems pretty obvious that the decades-old 35mm f/2 design didn't stand a chance against this new 40mm with all its bells and whistles.

It sounds like the new 35mm has all the benefits of the 40mm as well as IS and USM instead of STM. Of course it's also much more expensive, but so was the old 35mm despite it not being any better. The new 35mm gives a full extra stop of light gathering as well as 3-4 stops of shake correction, and for APS-C sensors it's the ultimate normal lens. It also got the same diaphragm upgrade IIRC, and the bokeh looks great in shots I've seen.

Would love to hear the reviewer's perspective on this 40mm versus the 35mm IS USM.

Comment edited 2 minutes after posting
Abu Mahendra

I own both the 35IS and the 40STM. In IQ they are neck-to-neck. The 40 is smaller, lighter and cheaper. The 35 has IS and f2. Pick your poison. I chose to keep both.


I’m in U.S & just ordered this lens directly from Canon due to an existing firmware advisory.
Now, instead of standard red-n-white colored box, mine arrived in black-n-gray and was made in Malaysia instead of expected Made in Japan.

[Everything I own by Canon is in red/white boxes, including batteries, lens caps and straps. The lens received also had a scratch on the glass.]
Canon told me “they ONLY make them in black/gray” boxes and “red and white” is for refurbished stuff (????), but mine was still assembled in Malaysia with Japanese glass".)
However, I found on the net lenses 4sale clearly photographed with red/white boxes and presumably made in Japan.
I returned the lens back to Canon and don’t know which way to go: to try to locate a Japanese copy on my own or go with the Malaysian?
Also, can someone confirm their copy is actually Japanese-made and in a red/white box?
The re-sale value of Japanese glass is MUCH higher than, (no offense), Malaysian/Chinese.



Alfanso, i bought this same lens in japan and they were made in malaysia too....
I think that maybe the cheap price of this lens is because of that, maybe they dont made this model in japan.

Jeremy Park

I bought this lens and then sold it immediately. My copy was poor perhaps, however tested methodically on a tripod against all my other lenses the results showed me that it was soft and not up to standard for professional use.


Mine was scary sharp on 6D. Perhaps you were unlucky. Variations happen.


Bad luck, Jeremy. Mine is excellent.


I love this lens, its scary sharp as onlooker say.
Make my 5Ds suitable in almost any situation.
Bokeh is ok, bag for buck its a must lens...
Its the ultimate street lens from canon...dont be fooled by the price. Love my L lenses but they are pretty heavy and some not as sharp as this one.


This lens is "smok'n hot". WOW!

1 upvote
Total comments: 15