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Canon EF 40mm f/2.8 STM review

June 2013 | By Andy Westlake

The EF 40mm f/2.8 STM was announced in June 2012, alongside the EOS 650D (Rebel T4i) SLR and EF-S 18-135mm f/3.5-5.6 IS STM zoom. These two lenses were Canon's first to use a linear stepper motor for focusing, giving rise to the 'STM' designation; this motor type allows silent refocusing during movie recording, and has therefore become widely-used in lenses for mirrorless cameras. This means that in principle the 40mm STM should be well-suited to working with the hybrid AF systems in Canon's recent cameras, including the 650D and its replacement the EOS 700D (Rebel T5i), the EOS M mirrorless model, and the diminutive EOS 100D (Rebel SL1).

The 40mm focal length may seem a bit odd - 35mm and 50mm are more familiar numbers to most photographers - but Canon has chosen it for good reason. Firstly it's relatively easy to design a small lens of this focal length for 35mm format SLRs, which means that it joins a distinguished line of compact 40mm primes from the likes of Olympus, Pentax and Voigtlander. Secondly, many photographers consider 40mm to be the 'perfect normal' lens on full frame, providing an extremely natural perspective to images.

The 40mm is the smallest EF lens Canon has made; it's just 22mm (0.9" thick), and weighs in at a mere 130g (4.6oz). It follows a recent trend for ultra-compact 'pancake' primes that are designed for maximum portability, encouraging users to carry their camera with them more of the time. But despite its size Canon has still managed to fit in a 6 element / 4 group optical unit that includes an aspherical element to help reduce aberrations. This makes it slightly more complex than its nearest equivalent, the Pentax smc DA 40mm F2.8 Limited that uses a 5 element / 4 group design in a lighter, even slimmer body.

The 40mm is also an inexpensive lens - indeed at around £150 / $199, it's Canon's second-cheapest for SLRs. But the elephant in the room is that one cheaper option - the EF 50mm f/1.8 II, which is half the price and offers substantially better light-gathering capability. Another option is the venerable EF 35mm f/2.0 - one of the earliest lenses made for the EOS system, although somewhat more expensive. In this review we'll see how the 40mm compares to these alternatives.

Headline features

  • 40mm focal length, F2.8 maximum aperture
  • Ultra-compact 'pancake' design: just 22mm thick
  • Linear Stepper Motor (STM) focusing with full-time manual override
  • 0.3m closest focus, offering 0.18x magnification
  • Canon EF mount for full-frame and APS-C SLRs, or EOS M using adapter

Angle of view

The pictures below illustrate the angle of view on full frame and APS-C. On full frame the 40mm is a classic 'normal' lens; on APS-C cameras it behaves like a short telephoto.

Full frame 1.6x APS-C (64mm equivalent)

Canon EF 40mm f/2.8 STM specifications

 Approx Price  • $199 (US)
 • £149 (UK)
 • €199 (EU)
 Date introduced  June 2012
 Maximum format size  35mm full frame
 Focal length  40mm
 35mm equivalent focal length (APS-C)
 Diagonal Angle of view  • 56.8º (full frame)
 • 37.1º (APS-C)
 Maximum aperture  F2.8
 Minimum aperture  F22
 Lens Construction  • 6 elements / 4 groups
 • 1 aspherical element
 Number of diaphragm blades  7, rounded
 Minimum focus  0.3m
 Maximum magnification  0.18x
 AF motor type  • Linear Stepper Motor
 • Full-time manual focus
 • 'Focus-by-wire' manual focus
 Focus method  Unit
 Image stabilization  No
 Filter thread  • 52mm
 • Does not rotate on focus
 Supplied accessories*  Front and rear caps
 Optional accessories  ES-52 screw-in metal hood
 Weight  130 g (4.6 oz)
 Dimensions  68 mm diameter x 22 mm length (2.7 x 0.9 in)
 Lens Mount  Canon EF

* Supplied accessories may differ in each country or area

If you're new to digital photography you may wish to read the Digital Photography Glossary before diving into this article (it may help you understand some of the terms used).

Conclusion / Recommendation / Ratings are based on the opinion of the reviewer, you should read the ENTIRE review before coming to your own conclusions.

We recommend to make the most of this review you should be able to see the difference (at least) between X, Y, and Z and ideally A, B, and C.

This article is Copyright 1998 - 2015 and may NOT in part or in whole be reproduced in any electronic or printed medium without prior permission from the author.

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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