Canon EF 40mm f/2.8 STM
Lab Test Results
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June 30, 2012
by Andrew Alexander
Launched with the Canon EOS 650D/Rebel T4i camera, the EF 40mm ƒ/2.8 STM is a tiny "pancake" lens, and is compatible with all of Canon's professional and consumer DSLR cameras. On Canon's APS-H cameras the lens will provide an equivalent field of view of 52mm, and on its APS-C cameras it provides an equivalent field of view of 64mm.
A lens hood is available for the 40mm lens (model #ES-52) but it is an optional accessory. The lens takes 52mm filters and is available now for around $200.
On both sub-frame and full-frame bodies, the Canon EF 40mm ƒ/2.8 STM provides very sharp results.
Mounted on the sub-frame 7D, the lens provides excellent corner-to-corner sharpness, especially when used wide-open at ƒ/2.8. Stopped down to ƒ/4, the corners get very slightly softer, while the center gets very slightly sharper, and it stays more or less like this stopped down all the way through to ƒ/8. In this case, "very slightly" is just that - you'll probably only notice the differences when shooting test charts - in practical usage, it will probably look quite sharp at any aperture. On the 7D, diffraction limiting sets in by ƒ/11, but you probably won't notice any impact until ƒ/16 (or even ƒ/22), where generalized softness is evident across the frame.
On the full-frame 1Ds mark III, the lens performs a little differently. Used wide open at ƒ/2.8, the central region of the frame is quite sharp, but corners are a little soft. Stopping down to ƒ/4 or smaller completely alleviates the corner softness, and while we wouldn't qualify the results as "tack-sharp" across the frame, they are quite sharp indeed. Diffraction limiting again sets in at ƒ/11, and as on the 7D, you'll notice it more at ƒ/16 and ƒ/22.
Resistance to chromatic aberration is very good with the EF 40mm ƒ/2.8 STM. If it does show up at all in your photographs, it will present as magenta-green fringing in areas of high-contrast, and predominantly in the corners of the frame.
Corner shading isn't really an issue when the lens is mounted on the sub-frame 7D; at ƒ/2.8, the extreme corners of the frame will be 1/3EV darker than the center. At any other aperture, corner shading is non-existent.
It's slightly different on the full-frame 1Ds mk III; at ƒ/2.8, the corners are almost a full stop darker than the center of the frame. At ƒ/4 this alleviates to just a half-stop darker than the center, and at any other aperture, corners are 1/3 EV darker than the center.
The Canon EF 40mm ƒ/2.8 STM is designed very well with regard to distortion - there is only a slight amount of barrel distortion, evident in the corners. In the worst case the lens is mounted on the 1Ds mk III, and we see +0.25% distortion.
The EF 40mm ƒ/2.8 STM uses a new focusing motor ("Stepping Motor Technology"), which, according to Canon, allows the lens to smoothly and silently focus, and when used in combination with Canon's new EOS Rebel T4i Movie Servo AF feature, achieve continuous AF while recording video. In practice the lens is indeed much quieter to focus than previous lenses, and is still very quick to focus, taking about one second to go from close focus to infinity. Attached 52mm filters will not rotate during focus operations.
Macro performance is sub-par, but then, this lens is not intended for macro usage. Minimum close-focusing distance is 30cm (around a foot) and maximum magnification is 0.18x.
Build Quality and Handling
The Canon EF 40mm ƒ/2.8 STM is small - perhaps the smallest lens Canon has built to date. The lens is less than an inch deep and weighs around 4 1/2 ounces - this is a lens that can easily fit into the smallest crook of your camera bag, if not your pants pocket. It doesn't make your dSLR any less pocketable, but it sure makes it a lots less imposing.
The lens itself is finished in Canon's standard matte black texture, and has a metal mount and plastic filter threads. The lens has very little in the way of control surfaces; there are two, the focusing ring and a switch to enable or disable autofocus ("AF / MF ").
The focusing ring is polycarbonate, and only 1/8'' wide. The STM focusing standard seems to be a fly-by-wire design, as the ring will turn forever in either direction with no increase in resistance to let you know you are at the end of the focusing range. There is some very slight lens extension as the lens is focused to infinity - the lens will extend by 1/4''.
Canon EF 35mm ƒ/2 ~$320
While starting to show its age (the lens was introduced in 1990) the Canon EF 35mm ƒ/2 offers very similar performance to the 40mm; it isn't as small, and costs a little more, as well as having an older focusing system.
Canon EF 50mm ƒ/1.8 II ~$120
Used at its widest apertures (ƒ/1.8, ƒ/2), this lens provides some extreme corner softness; but stopped down to ƒ/2.8, it's actually very comparable to the 40mm.
Sigma 30mm ƒ/1.4 EX DC HSM ~$490
It's a fair bit wider than the 40mm, and only available for EF-S bodies, but the Sigma provides very good performance.
It's impressive what Canon has managed to pack into a very small package here. Excellent results for sharpness, CA and distortion, and only some corner shading when used wide open on full-frame - which you could call the "character" of this lens. For the price, it's well worth the money.
Senior Editor Shawn Barnett grabbed the 40mm f/2.8 and headed out with the T4i and the family to see what it could do, seeing it as a great first prime for family shooters wanting a little better image quality than most zooms will deliver.
Check out his Hands-on Review on Imaging-Resource.com: Shooting the Canon 40mm f/2.8 lens.
The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Canon EF 40mm f/2.8 STM
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Canon EF 40mm f/2.8 STM User Reviews
10 out of 10 points and recommended by Prime Minister (40 reviews)Very compact, lightweight, fast-ish, sharp, good contrastNone
I like this little pancake. It produces images that are sharp and contrasty straight from the widest aperture. And that's on a full frame camera. Autofocus is fairly silent, accurate and fast enough for most situations. Build quality is decent and it has a metal lens mount. If you like the focal length, this is a no brainer. For the money, I can't fault it. I just have to give it a ten out of ten.reviewed June 2nd, 2015 (purchased for $167)
9 out of 10 points and recommended by babka08 (6 reviews)small (duh), sharp, contrast/colour, quiet, cheapit doesn't zoom from 18-400
This is a really great lens. It's tiny. And the fact that they include a very quiet lens motor, unlike Pentax with their noisy screw driven motors, is impressive. The image quality is just great. No question. I wonder about its longevity (like 10 years from now) as the electronics must be pretty tiny in there and it's plastic. But for what it costs it's still a great investment. The only question is whether you want a 40mm lens. It makes your full-frame Canon work like a rangefinder, so that's a great comparison. And it's about the same focal length as your smart phone. Another check mark. I actually find that I'm looking at things a little wider than a 'normal' 50mm lens these days, and when I want to go portrait I go up to 100mm. I'm talking full-frame. I can put my 6D with this lens in a little fanny pack (along with my Voigtlander 20mm pancake) and it's so nice and compact! I think it gives the Fuji x100 a run for its money (yes it's larger and heavier but) as a rangefinder type experience yet you still have a DSLR to work with other lenses. To conclude my ramble, don't hesitate to get one unless you don't want the 40mm length. But on a budget, it could replace your need for a 50 and 35. For under $200.reviewed July 24th, 2014 (purchased for $130)
9 out of 10 points and recommended by caMARYnon (8 reviews)discreet and light weight, very sharp, good colors and contrastslow AF, nothing else for the price
Very useful all around focal (just in case) with a tele on the body.reviewed October 25th, 2013 (purchased for $270)
9 out of 10 points and recommended by dugong5pm (52 reviews)sleek, very light, SHARP! nice build quality. beautiful!none
this is not the lens for everyone. Some might want faster lens or even the L-brand. For me, this one is a PERFECT lens for street. Optically superb & sleek design. Nobody's gonna be intimidated with this tiny lens. a perfect lens for fullframe sensors.reviewed October 12th, 2012 (purchased for $199)
Price is highly acceptable. If you're shooting people on streets, this one is a no brainer. must have!
9 out of 10 points and recommended by kinematic (13 reviews)Compact design, metal mount, STM motor (vs Micro Motor), short close up distance,Not weather sealed, noisy for video (but quieter than micro motor), no lens hood.
This might become my favourite walk around lens. It encompasses so much in one little $200+ lens. For its value, it gives you all the sharpness you'd expect in a prime, the speed of an F/2.8 lens, the low profile of a pancake lens, and a reasonably silent inexpensive STM motor (short for stepper motor).reviewed June 26th, 2012 (purchased for $199)
I tested out my new lens on my 5DmkIII, and some reports said it was slow for focusing, but honestly it wasn't all that bad. I actually found it probably on par with my Sigma 85 F/1.4 in reality (which isn't all that slow, but not super fast either).
The neat thing about this lens is that it has a wonderful close up range, so it's great for portrait as well as landscape or urban photography. If you're a street photographer, you'll love this lens.
I loved the fact that I could also just go with this in hand and capture a variety of scenes with it. Although today's weather wasn't cooperating, I did get a few shots off finding it very easy to use and flexible in all sorts of quick shooting situations. All my examples were frame and go, less than a couple of seconds. No tripods or a lot of time composing.
I also set up my 5DmkIII to not shoot lower than 1/125 of a second. This made it really handy to use this handheld in Auto ISO and not worry about needing to have IS. I had recently given up my compact Olympus EP-3 to my wife and was missing that as a quick small package for discrete street shooting, but I think this new lens will fill that void quite well (almost to the point of not caring if Canon comes out with a mirrorless system). Stripped down to just camera and 40mm lens is very nice to use. It's light in my hand and I maintain the image quality of an SLR. The only thing I need to add is a simple wrist lanyard to the kit so I don't feel like I'm going to lose my camera from my butter fingers.
The focus ring is small, and honestly I don't think I'll ever use it for manual focus (a fly by wire focus like the 85mm F/1.2 and the 300 F/2.8 lenses). One thing to note, if you do get this lens and you own the 5DmkIII, you'll need to update your firmware so it can do full time manual focus. Without the firmware update it does not manually focus when AF is set, only in MF mode. It's honestly not as bad as I thought it would be and cradling the base, it was easy to use my index finger to adjust the focus.
I've been testing AF on the new T4i as well, and I did try this lens out on that camera and believe it or not, it's the smoothest focusing of all the EF lenses with the new hybrid AF. All AF lenses seem to have this weird ratcheted like focus, which is annoying and useless. The STM motor is smooth, although slightly noisier than USM, it doesn't have quite the ratcheted AF sound when trying to get focus lock. Clearly this lens was being considered for video applications.
Lastly the one thing I do miss on this lens is a distance chart. This will make hyperfocal street focusing a little more difficult, but I guess the idea here is to lock your aperture, and trust in the AF to do the rest.
Full review on my blog:
Images examples here: