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Canon 40mm Pancake – How Did They Do That??

Published June 21, 2012

We got our first batch of the Canon 40mm f/2.8 pancake lenses in today and, as with all new lenses, I had to run them through Imatest to establish our acceptable standards for the lens. Let me start by saying I had low expectations. I don’t particularly like pancake lenses except on tiny cameras. They’re usually compromises between size and image quality and I’m an image quality guy, mostly. And, come on, it’s a $200 lens. But duty calls, so test them I must.

My first impression was the build quality was better than I expected. It has a metal mount, not plastic. The aperture blades appear more curved than most of the Canon 7 blade aperture rings, making a more circular opening. The little STM motor is not silent, but it’s pretty quiet. It’s also not lightning fast (as expected) but autofocus is certainly quicker than a Canon 85mm f/1.2 lens. And it’s amazingly tiny — the rear lens cap is about half as big as the lens. So far, so good, if the image quality doesn’t suck too bad.

Imatest Results

As always, these are Imatest MTF 50 results, so they reflect the performance at about 12 feet distance in our lab. Infinity and close-up results could be different to some degree. But the little 40mm has amazingly good numbers. To give some perspective, I’ve put it in a table with results for some other f/2.8 lenses. The higher number is MTF 50 at the center point, the lower number is average across the entire lens front measured at 20 points.

 Lens  Center  20 pt
Canon 40mm f/2.8 870 775
Canon 24-70 740 610
Canon 16-35 770 635
Canon 45 TS-E 785 660


You can see the average number is really excellent, which is especially surprising since pancakes often have poor corners. This is sooo not the case here that I’ll show you a graphed printout of a typical copy. Notice it retains excellent sharpness right out to the absolute corners on a 5D II.


One thing I have to note: the results were VERY consistent. We only had a dozen copies to test but there was  little lens-to-lens variation. As a rule pancake lenses don’t have lots of optical calibration adjustments inside, so they may depend on the manufacturing tolerances of the housing more than most lenses. Take this with a bit of a grain of salt, though, all the copies we tested were close in serial number, so there could be more variation when we get another dozen copies.

The 40mm f/2.8 lens is near peak sharpness wide open. The graph below shows 8 copies I tested at both f/2.8 and f/5.6. There’s only a slight increase in sharpness (I’m not certain that difference would be visible in a photograph, it’s within 5 SQF points.) That’s wonderful, but I want to point out that a lot of lenses that do improve stopped down (like the 3 in the table above) would ending up being sharper than the 40mm at f/4 or f/5.6.

The only other comment I have about the little lens is that manually focusing, while possible, is rather difficult: the focusing ring is really thin and I found a fingernail moves it better than my whole fingertip. Mostly, though, it has a small range so a tiny movement can move the focus a lot. But then, one of the main purposes of this lens was to provide smooth video autofocusing.

Overall, though, I’m extremely impressed. I’d be impressed if a lens this size and price was just decent, but this one is excellent. I might as well go ahead and get in trouble with the business manager: if you think you want this lens, just go ahead and buy it. At this price, unless some of the more thorough reviewers find something I missed on this quick overview, you can’t go wrong.

Roger Cicala

June 2012

Author: Roger Cicala

I’m Roger and I am the founder of Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in New Items
  • Resolution and IQ considerations aside, does it really make sense for lensrentals to stock that lens? Given the price it appears a no-brainer to just go out and buy one 😉

  • This lens sounds wonderful for an auto-focus camera. The short movement of the focus ring causing major focus changes and the focus ring being so narrow both sound as if it wouldn’t be that great a lens for non-auto-focus cameras such as my 5DII.

  • Dennis

    Fast focusing? You said it it fast, would you say it is a worthy replacement for my 50 1.8 that I used for indoor action shots? I get a lot of misfocused images with my nifty fifty. Some is my fault certainly but some I can’t help but think is that lens isn’t focusing fast enough.

  • yudi wied

    i think this lens will be match with rebel t4i / 650d. Because 40mm have new stepping motor system for smooth auto focusing with video mode. said canon will release compact mirorless system camera in 2013 ,maybe like canon g1x with interchanegable lens.( sorry with my english )

  • jpjeff

    does anyone know if this lens allow auto focus in video on 5dIII?

  • Mark

    I have long been a fan of pancake lenses and the Tessar design that spawned them. This is a classic design noted for sharpness , contrast and simplicity. Modern refinements in coatings, glass and construction just make it better. Thanks to Canon we now have one that will revive interest in a very cool design.

  • James

    This resolution characteristic (relatively even across the frame and at all apertures) looks very similar to that of the Pentax 40mm F/2.8 pancake(s) (

  • johann

    Do you have any very sharp pictures with it?

  • Jerry Russell

    The cumulative results of this series of experiments is indeed getting very interesting. Roger, this is a great service to the photographic community, especially the studies of sample variation.

    I had forgotten about that article about 50mm lenses. Towards the end of the article, it’s mentioned that there are indeed some lenses that give 1100-1200 lph on Canon and Nikon FF. That was before the D800 came out. Would those be long telephotos like the 135L, 300L, etc?

  • Ignat Solovey

    Your conclusion is what I expect from this lens, no less. Anyway, it’s a thing long dreamed of, a tiny normal prime (“fifty”) for my 1D Mark IV (and, earlier, 1D Mark IIN). Some time ago I really considered buying Zuiko 40/2, and I would, if it wasn’t so rare and, obviously, ridiculously overpriced thanks to collectors and the fact that Maitani Yoshihisa, Pen and OM original developer, may he rest in peace, created that 40/2 for himself (I have also OM-4 body and pretty decent lineup of midrange Zuiko primes and one zoom). The only thing which stopped me from getting that Zuiko, except price, was lack of autofocus. Now Canon made even better thing than I ever imagined. Just why they don’t add manual sound controls in 1D Mark IV, while it’s already done this or that way in all other Canon HDSLRs save for 500D and 7D (500D is obsolete, 550D is ok with Magic Lantern and new 7D firmware is pretty certainly rumored to be on the way. Being photojournalist, I don’t want to buy one more body to do small video interviews and recording street music, even the cheapest one, that means more bulk, not to mention weak and incompatible batteries… And no, I don’t want to mess with external recorder like I do now, sometimes it’s pretty easy to forget to push two REC buttons instead of one).

  • Oliver Roxas

    can’t wait to get my pancake… already on its way!!!

  • Did you order the lens hoods, too, i.e. the ES-52? Harder to find than the lens!

  • Yemin

    If I have a 50mm F/1.4 why would I get this lens. I do have a pancake 20mm F/1.7 on my tiny GX1, there it is a perfect fit.

  • Jim Colwell


    Thanks for sharing your results. The consistency is encouraging. This is probably a good example of the KISS Principle in operation.

    I’ll get one to compare with my Tessar 45/2.8, Ultron 40/2.8, and a few small 50’s. I’ll post the results on the usual forum. That would be FM. 😉

    Cheers, Jim

  • Thanks bluto. I read that article before but it’s been a while. Alright, on that note, Roger, have you guys ever thought of doing a database of your imatest results? I think that would be really cool and could even be something you guys list on each product page maybe.

  • Chris

    Nicholas, I believe the reason for the focal length is in relation to the distance of the EF mount (which is around 43ish mm). Its the simplest lens configuration to be right around that FL (thus why good 50mm lenses are cheap and plentiful from Canon, and 14mm or 600mm are not). Same reason why the Panasonic pancakes are 17/21mm, which is right around the flange distance of m4/3 (20mm). A lens with a shorter focal length has to have more elements to bend the light, and likewise for a lens of longer focal length.

    The details are far more complicated than that, but to keep a lens pancake size, it has to be around the same FL of its mount; or sacrifice a lot

  • Very well, thank you: I’ll buy it as soon as possible for my 5D mark II!
    Finally a lens – qualitative, light and cheap – good (may be…) for 35 and 50mm fans
    as I am. Thanks again.

  • I have a Contax Ziess 40mm pancake (on my 5D mk2), anyone know what its worth & or how it rates to the Canon?

  • bluto

    Lens rentals did a similar test with a whole bunch of 50mm lenses. The 40 matches up well wide open.

    I’m not sure they’re perfectly comparable, the the 45mm TS had similar numbers then and now.

  • I had a change to check this lens out this morning and it is an outstanding value. Thanks for the great review and for putting those numbers up so we can compare. Now, where is Nikon’s pancake?

  • Roger Cicala

    Sanford = yes, of test targets. We’re in a windowless lab, unless we take pictures of each other (not a worthwhile thought), test targets are all we have.

  • Jerry Russell

    What do you think this lens would do on an APS-C camera like a 60D or T4i? Would it be stuck around 625 lph peak at f/5.6, as you would guess from the crop ratio? Or would it benefit much from the extra pixel density? I think it’s interesting that the better M43 and NEX-7 lenses seem to be just as good as Canon full-frame at its best (around 1000 lph) while crop DSLRs are lagging behind. Or, are there any lenses that can do 1000 lph on a crop?

  • Bob B.

    Great review, Roger. Thanks for posting it…I now feel well informed about the this little 40mm….but…do I really need this little ditty???…I am on the edge of my seat waiting on the 24-70mm IS II. …and I have two really GREAT MFT cameras with pancakes galore. So I am guessing, even tho I am tempted..and I want to fill a void because I have no kit lens at the moment (I sold my 24-105mm to buy the new 24-70mm BEFORE Canon changed the shipping date)…so…I am going to fight my lens disease for today and put the $200 toward the uber-expensive 24-70mm II…but it looks like a GREAT little lens!!!!!! Thanks again.

  • The numbers and price look good, but I’m still puzzled as to what body the Canon designers had in mind when they made this lens. It’s a great focal length on FF, but an itty-bitty pancake on a 5D-sized brick seems a bit silly. It might make some size sense on a little T3i, but 65 mm-e is a focal length of questionable utility at best to most folks.

  • Sanford

    Did you actually try taking photos with it?

  • Michael B

    Thank you for your interesting report – it’s good to hear your impressions from “experimental data” and combine it with my first photographic impressions of that lens (I made my first photos with it yesterday).

    I wished always that camera companies (for me Canon for compatibility) combine standard lens designs/lens types with current technologies.

    The new 40mm pancake does exact that: Combine a more or less boring focal length/max aperture with great coatings, an aspherical element and perhaps good glasses. I expected spectacular quality from the basic setting and my first photos confirmed that by very contrasty images and exceptional flare resistance – once again: A “boring lens” which incorporates current technologies to act as a great tool!

    Thanks again for your work and for publishing it – Michael

  • Roger Cicala


    The 40 is fairly unique in that it just doesn’t get much sharper stopped down (the green triangles are at f/5.6). Most lenses do improve for two stops or so, more than the 40 does.

  • RobertZ

    Thanks a lot for sharing your test results and impressions with the rest of us! Seems like this could be a really good lens for those who want to shoot wide open. Can share with us how this lens compares to the lenses above when stoppped down (I assume the results above and the diagram are at f/2.8)? You said the other ones are sharper stepped down, but how much, just a bit or a lot? Also, how does it compare to 50mm f/1.4 at 2.8? Again, THANKS!

  • Thank you for your review. I have 1 on order and can’t wait to start using it. I am going to be doing something quite different with it. I will be using it on a Canon T2i that will be suspended in the air from a kite line. I anticipate having some unique new images from my travels in the coming months.

  • This lens looks excellent. Roger, I don’t know if you have the time but it’d be interesting to see an imatest comparison between this and the 50 1.8 or 50 1.4 at the 2.8 aperture. Oh by the way just ’cause you said to just go ahead and buy it doesn’t mean I’m not going to rent it from you guys at least once. So your business manager can take a sigh of relief. It’s a cheap rental as long as I’m already renting something else and will definitely be something I look forward to trying out. Great job as always.

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