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Canon EF 40mm f/2.8 STM Pancake Lens (Full Review!)

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Today I’m reviewing one of the oldest lenses in my camera bag. The Canon EF 40mm f/2.8 STM pancake lens has outlived many excellent lenses in my kit, and I use it almost daily.

So what makes this miniature optic so compelling? Is it right for you, or should you look towards the nifty fifty, or perhaps a 35mm lens instead? Read on to find out.Canon EF 40mm f/2.8 STM Pancake Lens [Note: ExpertPhotography is supported by readers. Product links on ExpertPhotography are referral links. If you use one of these and buy something, we make a little bit of money. Need more info? See how it all works here.]

Overview of the EF 40mm f/2.8 STM

This lens is one of Canon’s newer additions to the EF lineup of DSLR lenses. It was introduced in 2012, so it’s a fairly young lens as far as EF lenses go. It is among the smallest full-frame DSLR optics ever made.

As of today, it’s the smallest lens available for Canon DSLRs, along with its crop-sensor (almost-)equivalent, the EF-S 24mm f/2.8 STM. The latter was my first lens ever – so it seemed reasonable to purchase the 40mm when I jumped ship to full-frame cameras.

Besides the convenience its size provides, the 40mm is excellent optically. It outperforms its closest alternative, the 50mm f/1.8 even at f/2.8.

Another advantage it has over the nifty fifty is better close-up performance. Even by default, it’s capable of slightly better magnification.

With extension tubes, however, the gap broadens.

The 40mm with its shorter base focal length is a more effective to-be-macro lens. Not to mention that it retains sharpness much better than the 50mm at close focusing distances.

Read about using this lens for low-budget macro photography in this article. 

Canon EF 40mm f/2.8 STM Pancake Lens

What’s in the Box?

As a fairly cheap lens, its packaging is moderate. Besides the lens (with both caps provided) and the user manual, there’s nothing else in there.

The ES-52 official lens hood is available separately, but I don’t recommend purchasing it for several reasons.

It has identical no-brand alternatives for much cheaper. It also does almost nothing to protect the lens or block sunlight with its minuscule size. Luckily, the lens’ optical performance makes it largely unnecessary.

Who Is the EF 40mm f/2.8 STM For?

This lens is for everybody who wants to basically replace the body cap on their camera. With its size, it’s ideal for quick grab-and-go shoots, street and documentary, photojournalistic, even event photography.

Even if it can’t entirely hide the fact that you’re carrying a bulky DSLR, it makes it somewhat less obtrusive and frightening. This helps with portraits, especially candid shots.

It also helps to get into places where a large camera wouldn’t normally be allowed. I was able to get away shooting concerts on several occasions with this lens and my 5D camera.

Still, the 50mm f/1.8 STM gives you similar advantages, even if it’s a bit larger. There are several reasons I chose the 40mm over that in the long run, after having used both for years.

First, that little size difference does matter, and the 40mm has the advantage there. Second, I don’t shoot portraits as often as street photography. There, corner sharpness is key, so the 40mm has won again. It’s also a little bit sturdier built.

I don’t recommend this lens for crop sensor cameras.

The 40mm focal length is not really convenient on a crop sensor, at least in my experience. Choose the 24mm f/2.8 STM instead, which is the 40mm’s little sibling.A crowded street

Key Features

Mount and Compatibility

The Canon EF 40mm f/2.8 STM is made primarily for full-frame EF-mount cameras. These are the Canon EOS 6D, EOS 5D, and EOS 1DX/1Ds series of digital cameras, as well as all of Canon’s 35mm film cameras since 1987.

However, the lens will work perfectly on crop-sensor EOS bodies (such as the 7D, 10D-90D series, and all the Rebels). It can also be adapted without loss in autofocus speed to Canon’s full-frame mirrorless R bodies (currently the R, RP, R6, and R5).

I actually used it to test and review the EOS RP, as I found them to be a great, small combo.Canon camera with EF 40mm f/2.8 STM Lens

It will work just fine with a slight drop in autofocusing speed on Canon’s crop-sensor mirrorless EF-M-mount cameras (e.g. the M100, M50, M5, M6).

You can also attach any EF mount adaptor currently in use to this lens. These include adaptors to Sony E-mount, Fujifilm X-mount, Micro Four Thirds, Nikon Z-mount, Leica L-mount, and more.

Autofocusing speed and reliability on these off-brand cameras will depend on the quality of the adaptor used.Canon camera with EF 40mm f/2.8 STM Lens

Image Quality

The 40mm is among the best Canon lenses in this focal length range. Right from f/2.8, it provides excellent sharpness from corner to corner. It doesn’t get better beyond f/4.

As I mentioned, it retains sharpness really well with extension tubes at close focusing distances as well. In most aspects except aperture, it’s in the same league as the EF 50mm f/1.2L, which says something.

Its distortion level is excellent, barely noticeable on full-frame cameras. It’s also easy to correct, if you want 110% straight lines everywhere, as it’s a very simple barrel-type distortion with no weird deformations.

Its out-of-focus background looks excellent. It has pleasant smoothness, no ugly transitions, and minimal longitudinal chromatic aberration.

Chromatic aberration on contrasty edges is also well-controlled, significantly better than on the 50mm f/1.8.

Flares don’t pose much of a problem, and although they do show up, they’re quite unobtrusive and don’t result in a loss of contrast.A LATAM airplane on a runway


The 40mm f/2.8 STM has great autofocus, but very limited manual focusing capabilities.

Its autofocus system is quick and very accurate. It’s responsive in very low light, too, better, than you’d expect from an f/2.8 lens and better than the 24-70 f/2.8 II zoom at 40mm.

My copy has never had any issues, not even micro-adjustments required. This stands in stark contrast with the 50mm f/1.8 STM, of which I had two faulty samples before getting one that was consistent, and even that had to be micro adjusted.People walking through busy streets at night

The 40mm pancake was one of the first lenses to include a stepping autofocus motor instead of the traditional USM motor, hence the ‘STM‘ mark in the name.

This technology has helped a lot with smooth continuous focusing, a great improvement for video shooters.

However, this also means that the manual focusing ring and the lens elements are no longer physically connected. This is a bummer for those who want to manually focus often.

You can’t focus when the camera is not turned on, not even in manual focus. The ring itself is also almost non-existent, being a thin plastic piece right at the front of the lens. So, no manual-focus magic here.

There is no full-time manual focus override, and as expected at this size, there is no distance scale. When focusing, the front element extends out of the barrel, but it doesn’t rotate. Its minimum focusing distance is 0.3m.Canon EF 40mm f/2.8 STM Lens

Handling and Build Quality

The 40mm f/2.8 STM pancake lens is mostly built of plastic, with the exception of the lens mount, which is metal.

Despite this, it seems rather solid, and it has been taking the hits fiercely throughout years of work and travel. Marks of use, of course, are visible, but no issues of reliability have arisen.

It doesn’t have weather-sealing, though, and with the moving front element, I never wanted to test just really mow much this is true. This is not a rain or dust-friendly lens.

The only thing occupying the side of the lens is the manual/autofocus switch.

It has a 52mm filter thread. Filters of this size are cheap and widely available. Be aware that the autofocus motor doesn’t tolerate more than one filter in the long term. With two filters, it makes weird, whirring sounds, presumably due to the weight.

The lens is 68mm in diameter (not much wider than the lens mount itself), and 23mm long. It really is tiny, but at 130g, it feels quite dense.

You can attach several extension tubes and still get very usable results, both in image quality and handling. However, you’re likely limited to focusing by getting closer or farther away, because of the poor manual focus implementation.

That’s not an issue with macro rails or free hand-holding. I’ve written about an excellent cheap macro setup that includes this lens in this article.
A close up of flowers

(Want to get even closer with macro images? Learn how to take them with our Macro Magic course!) 


There is one alternative to the 40mm pancake, the aforementioned 50mm f/1.8 STM, the newest edition of the nifty fifty.

It’s slightly cheaper, and more than a stop faster. This is countered by the slightly better image and build quality of the 40mm, and the latter’s smaller size.

Also, if you’re searching for a crop-sensor alternative, look no further than the EF-S 24mm f/2.8 STM.

Our Verdict

The 40mm f/2.8 STM doesn’t take up much space but gives you excellent results. It’s a lens that can be your long-term partner in photography.

It has definitely been mine.

Check it out on Amazon here.


Image Quality (25)
Focusing (20){{column-name-2}}: 15
Build and Handling (20){{column-name-2}}: 14
Value for Money (20){{column-name-2}}: 19
Miscellaneous (15){{column-name-2}}: 9
Total (100){{column-name-2}}: 78


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