Canon certainly hasn’t rushed to market with an awful lot of hardware and updates for their EOS M platform. The EF-M 22mm f/2 STM is one of the two release lenses for the EOS M and one of  the only 2 EF-M lenses Canon released in the United States.

All that said, while Canon seems quite halfhearted about their EOS M platform, they haven’t half-assed the glass for it. The EF-M 18-55mm f/3.5-5.6 IS STM is one of, if not the, sharpest 18-55mm kit lens on the market, and the EF 22mm f/2 STM, even with its low $180 price tag, is no joke of a lens either.

The EF-M 22mm f/2 STM is, in my opinion, how the EOS M is supposed to be used, a revelation that I find even more surprising knowing how strongly I favor zooms over primes for their flexibility. That said, on the EOS M I find zooms to be unwieldy. The camera is small enough and light enough that I can use it one handed, and having a zoom that I have to use a second hand kind of goes against that.

Build, Controls, and User Experiance

To say the EF 22mm f/2 STM is small would be an understatement. Many would call it a pancake lens, a description that it does fit, having a diameter that’s larger than its depth. Overall, we’re talking 2.4 inches in diameter by 0.93 inches thick (60.9mm x 23.7mm).

Like the EF 18-55mm f/3.5-5.6 IS STM, there’s a nice density to the lens that isn’t readily there in a lot of current SLR lenses. That’s not to say it’s heavy, at 3.7oz (105g) it’s not, but it does feel solid for the size. Actually, the density and feel of the EF-M lenses is something I really like. To me they feel a lot like old manual focus lenses in terms of build. They’re small and solid in a way that many SLR lenses don’t seem to be anymore, even if they’re really well built.

The finish is textured matte gunmetal gray, the same as all the other EF-M lenses. I can’t speak for the longevity of the finish, as I haven’t had any EF-M lenses long enough to really get a proper feel for how they’ll hold up in the long term.

Filters and Lens Hoods

The EF-M 22mm f/2 STM has the smallest filters I’ve ever seen in a Canon lens, at 43mm. In fact, the only Canon lenses with smaller threads I can find were made in the 1950s for Leica S mount cameras.

I can’t really comment on filter compatibility right now, as I don’t actually have filters small enough to put on the lens. And quite honestly, I don’t know if I’ll be getting any anytime soon.

I don’t see a whole lot of need to put a clear protective filter on the lens, the front element is small and doesn’t protrude from the face. Moreover, a decent protective filter in the 43mm mount size would run $50, more than a quarter of the cost of the lens itself.

The field of view is suitable for using a polarizer. Though I’m not sure I’d run out and buy a 43mm circular polarizer (CPL) for this lens, instead, I think I’d buy a 52mm CPL, which will also work with the EF-M 18-55mm f/3.5-5.6 IS STM, and a 43mm to 52mm step up ring. That should also insure that the thickness of the CPL won’t vignette—but again, I don’t have filters this small so I haven’t tried it yet.

One final thought on filters. For creative effect filters on a regular SLR I really like my 100mm rectangular filters (Lee or Cokin Z-Pro), however they’d be massively unwieldy on this lens and system. Those would be hugely unwieldy on a lens this small, I’m not even sure you could get you hand on the camera properly, even. Lee has a smaller solution, the Seven5 line, which would be a better fit, I think. Even then, given the thickness of the lens, it might not work that well.

Like the other Canon pancake lens (the EF 40mm f/2.8 STM), the EF-M 22mm f/2 STM uses a screw on hood instead of a bayonet mount one. Also, like all non-L lenses, the EF-M 22mm f/2 STM doesn’t come with the hood in the box. The official Canon part is the Lens Hood EW-43. They run about $15, with 3^rd party variants coming in around $11.

One frustrating point with the Canon hood is that Canon elected not to thread the outside part. They could have easily made the hood a combination hood and 43mm to 52mm step up ring , to more easily share filters with the EF-M 18-55mm f/3.5-5.6 IS STM.

Focusing and the Focus Ring

The ring follows the same design motif as other EF-M lenses do. The rotating ring is about 1/2 inch (~12.5mm) wide, with the front most 1/8” being a knurled grip. Also like all the other STM lenses, the EF-M 22mm f/2 STM uses a focus by wire. This has two broadly ranging implications on feel and operation.

Since focus ring is not physically coupled to the focusing helical itself, the ring’s feel can be made to feel like anything Canon wants. Fortunately, Canon didn’t cheap out massively on the feel of the ring. In fact, much like I noted in my EF-M 18-55mm f/3.5-5.6 IS STM review, turning the ring feels a lot like turning the focus ring on an old well-built manual focus lens, it’s very smooth and well damped.

The same decoupling, however, also means there are no hard stops, or even soft stops like found on ring-USM lenses. The focus ring just turns and turns in either direction indefinitely.

The second major implication is how focus by wire affects the operation of the lens. The operation of the lens is entirely dependent on the camera it’s mounted on, in this case the EOS M. Let me start with the basics, if the camera is off, the lens won’t focus at all. With the camera on how the lens behaves depends entirely on how the camera is set.

Unfortunately, this is one place where the super clean design of the lens can be a bit annoying. There’s no auto-/manual-focus switch on the lens, and the EOS M carries the same kind of minimalist controls, meaning there’s no quick way to change the electronic focusing mode.

The focus by wire system can operate in one three modes. These can be selected though the shooting 2 menu (red camera with 2 dots) on the EOS M. If the camera is set to AF mode, then the lens’s focusing ring is disabled. No amount of turning it will affect the lens’s focus.

The second option is full manual focus mode, which works like any other manual focus lens. At any time the camera is on, turning the focus ring will cause the lens to focus.

The third, and final, option is AF+MF. In this mode, the lens’s focus ring will adjust focus only after the AF system has tried to focus (either achieving focus or giving up) and while the shutter button is being held in the half pressed. Strictly speaking, all Canon focus-by-wire lenses behave this way including all the STM lenses in EF and EF-S mounts.

Once you’ve used it a couple of times, the focus by wire system isn’t entirely bad. I’ve never noticed any significant focus lag, however, without a distance scale, either real or virtual, or hard stops it’s hard to tell. Likewise, it’s impossible to tell if the lens is focused to infinity or close focus simply because there is no stop or distance scale, and no indication on the camera that you’ve reached the stop.

One nice aspect of the focus by wire setup on the EF-M 22mm f/2 STM is the focus ring throw. When manually focusing, in either MF mode or AF+MF mode, it takes approximately 360° of focus ring rotation to focus from infinity to the minimum focus distance.

Unlike the EF-M 18-55mm f/3.5-5.6 IS STM which uses an internal focus arrangement, the EF-M 22mm f/2 STM uses what Canon is calling a “unit focus” system, or what I would have called an overall linear extension system. That is when focusing the entire “unit” containing all the lens elements is moved fore and aft to focus. Fortunately, the system doesn’t rotate so it’s not an impediment to using creative filters.

Quirks

There are two quirks/announces I’ve found with the EF-M 22mm f/2 STM, and both can be slightly annoying.

First, the rotating focus ring takes up half the lens’s surface, and there aren’t any hard stops, so when mounting and unmourning the lens there’s not a lot of surface to hold. On a number of occaions I’ve gone to remove the lens only to depress the lens release lock button and turn the focus ring and have nothing happen. The same goes for mounting the lens, put it on the mount, turn, nothing, only to realize I’m turning only the focus ring.

Not that it’s a huge deal, and honestly I’d rather have the 1/2” wide focus ring, than none at all or one that’s only 1/8” wide.

The second issue is with startup/shutdown and storage. In the off/stored position, the lens retracts to that the front of the filter threads are flush with the front of the lens barrel. In use, the lens extends at a minimum of 1/8^th inch (3.2mm) forward—though it can extend as far as 1/4-inch (6.4mm) when focused at the minimum focusing distance. However, the extension and contraction only happen when the power button is cycled. If the camera puts itself to sleep via the power saving timeouts, the lens will not retract and the green power/access lamp will stay illuminated until you turn the camera off with the power button.

Non-Optical Performance

The EF-M 22mm f/2 STM is hit with a double, or maybe even triple, whammy when it comes to autofocus performance. To start with, the EOS M platform, even with the latest firmware updates, isn’t the fastest focusing platform in existence. Compounding the matter, the STM lenses don’t seem to focus nearly as fast as their USM counter parts.

Qualitatively, I find the AF performance to be acceptable so long as you’re not trying to shoot sports or fast-paced action. That said, it does seem slower than the EF-M 18-55mm f/3.5-5.6 IS STM at a similar focal length.

Quantitatively, the EF-M 22mm f/2 STM on an EOS M with the v2 firmware focuses from infinity to 3 feet in 0.48 seconds in moderately bright conditions (1/400^th f/2 ISO 200), and refocuses on that point in .33 seconds. That is noticeably slower than the 0.36 seconds (infinity to 3’) and 0.21 seconds (refocus) the EF-M 18-55mm f/3.5-5.6 IS STM sees under the same conditions.

One final note about the AF system on the EF-M 22mm f/2 STM, the stepper motors are supposed to make the lenses quiet. On the EF-M 18-55mm f/3.5-5.6 IS STM, the lens is dead silent. The EF-M 22mm f/2 STM is quite, but not silent.

I think the big difference is from the focusing mechanism. The 18-55mm’s focusing system is entirely internal to the lens, and so the lens barrel itself will muffle any noise it might make. On the other hand, the 22mm f/2 has to move the whole “unit” which is leave room for something to rub and gaps for sound to escape.

I’m making a point to bring this up, because it seems to be normal for the lens, at least in still photography mode. However, in video mode the lens seems to be dead silent when focusing, perhaps

What I think is happening, is that in photo mode, the camera will drive the AF system much faster than it will when shooting videos. This not only smooths out focus shifts, but it also makes the AF system much quieter regardless of the lens being used.

Optical Performance

Optical performance seems quite good. I’m currently in the process of revamping my optical testing situation, as I don’t find it suitable for what I want to do with my reviews. As such I don’t have any hard numbers at all from my own testing. If that’s your be all end all criteria, then I would point you towards DXOMark’s optical tests on this lens.

Subjectively, comparing the lens to the EF-M 18-55mm f/3.5-5.6 IS STM at ~22mm, the EF-M 22mm f/2 STM is as sharp as, or sharper than, the already quite good zoom at f/2. Stopping down the two stops to a aperture matching f/4 and the 22mm f/2 clobbers the zoom. Better yet, distortion is virtually non-existent when looking at images, and DXOMark seems to back this up, though admittedly I haven’t measured it for myself.

I don’t pay much attention to vignetting and chromatic aberration anymore, as they can easily be cleaned up either in the camera or in post. That’s said, there’s noticeable vignetting in the corners wide open on the EF-M 22mm f/2 STM, if you turn off the lens corrections and have an even edge to look at.

Video Performance

Admittedly, I haven’t done much with this lens with video outside of some quick tests. Since the lens isn’t a zoom, parfocal stability isn’t a concern.

Breathing, however, is a concern. Breathing, for those not familiar with the term, is the unwanted change in framing associated with the change in focal length that happens when focusing. While the lens’s AF system is designed for video, the optical system isn’t quite as optimized. The EF-M 22mm f/2 STM breaths, it’s not horrible at moderate working distances, but enough that it’s noticeable.

I also have some concerns about the lack of image stabilization. While stabilization isn’t strictly necessary for a wide-angle still lens—though I’d still appreciate it in this case—because of the low shutter speeds necessary to get shake free images. However, when shooting video, dynamic IS goes a long way towards smoothing out the small shakes in handheld video that often make it distracting and annoying. Unfortunately, there’s no IS system in this lens. Camera shake is a problem, in my opinion. You either need very steady hands, or some kind of small stabilization system (Small steady cam, or a Manfrotto Fig Rig) is probably not a bad idea.

One difficulty I did find, and it’s noticeable in the breathing demo video, is that the long focus throw coupled with the size of the lens makes it difficult to smoothly pull focus manually without doing it in little chunks. There are certainly ways to overcome that issue, but they will require some outside work. One possible solution would be to rig up a simple focus lever.

Conclusions

I started out this review by noting that this is how I think the EOS M best works. The EF-M 18-55mm f/3.5-5.6 is nice, but it’s bulky and it makes the tiny camera a bit more unwieldy. The EF-M 22mm f/2 STM, however just fits in perfectly. The real shame is that it’s the only fast small prime for the EOS M, as that’s what the system really craves.

Normally, I’d spend a moment here talking about alternatives. Both the EF-M 18-55mm f/3.5-5.6 IS STM, and the unreleased in the US EF-M 11-22mm f/4-5.6 will give you coverage at 22mm, but neither are as fast—by 1-1/3 stops in the case of the 18-55mm and 3 stops in the case of the 11-22mm.

Moreover, there aren’t any competing third party options. Only Samyang has announced a EF-M mount lens, a full manual 16mm f/2, which field of view wise, is a wide-angle lens where the EF-M 22mm is more of a wide normal. Sigma has also indicated that they have no current plans for releasing EF-M versions of their DN (designed for mirrorless) lenses either.

So that’s that. If you want a compact fast lens to put on your EOS M, this is the lens to get. I mean it’s not as though you’re settling for second-class optics anyway.

Lens Data