Yet Another Sigma 50mm Art Post

Published April 30, 2014

I suspect I’ll never be on any manufacturer’s “early review copy” list for new lenses. There are already plenty of good early lab reviews on the eagerly awaited Sigma 50mm f/1.4 Art lens at SLRGear, Lenstip, and DPReview, among others. So when we received our first Sigma 50 f/1.4 Art lenses for rental stock I really didn’t plan on posting about it.

But I always think it’s worthwhile to review multiple copies of a lens bought off-the-shelf from retailers. Plus, we’ll have our new MTF bench installed in another week or two, and I want to do some comparisons using the bench versus Imatest, so when we got our first seven copies of the Sigma 50mm f/1.4 Art in yesterday I compared them with Imatest. I decided I might as well post the results, even though I’m a bit late to the party.

The comparison most people are making is with the Zeiss 55mm Otus, because the Sigma Art and the Otus are both newly designed, excellent lenses. I added the Canon 50mm f/1.2 into the mix, since I suspect some 50mm f/1.2 shooters are wondering if they should migrate to the new Sigma. I choose a beat up and battered two-year-old Canon for the photo below, just to emphasize that it goes into this contest like a prize-fighter coming out of retirement for the fifth time. True, it was released in 2006, but even that was something of a comeback. The optical design dates back to the early 1980s.

As always, this isn’t a complete lens review, just lab testing and comparisons on multiple samples.

Tale of the Tape

The Canon has a simple double Gauss design with 8 elements in 6 groups. The Sigma has 13 elements in 8 groups, while the Otus has 12 elements in 10 groups.

Left to right: Zeiss 55mm Otus, Sigma 50mm Art, Canon 50mm L


The other specifications are pretty clear: the Zeiss is really big and really expensive, the Canon is smallest and goes to f/1.2, the Sigma is easily the least expensive and middle-sized.

  Canon 50mm f/1.2 L Sigma 50mm f/1.4 Art Zeiss 55mm f/1.4 Otus
Weight (lb)1.31.792.27
Length (in)2.583.935.66
Aperture Blades899
Filter thread72mm77mm77mm
Price $1619$949$3990

This isn’t a lens review, but for someone who does a lot of manual focus, I absolutely love the smooth, long-throw focus ring of the Zeiss. The Sigma Art manual focus ring is really excellent, too — very smooth and accurate. After using those, the Canon’s manual focus ring feels like a greased pig.

The Sigma’s autofocus was quick and accurate on a 5D Mk II and 6D in good indoor lighting, but I didn’t stress test it under difficult conditions or with moving targets. You’ll want to read some hands -on reviews to get better information about that. The Zeiss’s autofocus system, of course, isn’t.

Let’s Roll Some Numbers

Every review I’ve seen so far states the Sigma Art’s resolution numbers are very close to the Otus. I’m not here to argue, as the graph below shows. (Testing distance was at 10 feet for the Sigma and Canon, 11 feet for the Zeiss.)

MTF50 in Line Pairs / Image Height for 7 copies of each lens, all tested at f/1.4


I imagine, just like me, you notice there’s a bit more spread for the Sigma copies than either the Canon or Zeiss copies (especially when you consider the Sigma copies were all new-in-box and the others were used copies off of our shelves). I think this is just fairly normal sample variation — if I had 30 copies instead of 7, we’d probably be seeing similar pattern sizes for all 3 lenses. But I won’t be comfortable with that answer until I have the chance to test another 15 or 20 copies. We won’t be getting anymore this week, (they are understandably hard to come by right now) so I’ll add further testing as an addendum to this article in a week or so. I did, of course, repeat these test runs multiple times to make sure there wasn’t any testing problem, and there wasn’t.

Remember also that we’re looking at hair-splitting MTF numbers here. Even the two “lower” Sigma copies are clearly outresolving all of the Canon copies, and the Canons were shot at f/1.4 to make sure the playing field was even. Carefully testing on an ISO 12233 chart showed all of the Sigma lenses resolved well with no soft corners or astigmatism, which is the main reason I think this is just sample variation.

Stopping Them Down

Watching how the lenses behave as they are stopped down is interesting. The graphs below show center, weighted average, and corner resolution (corner numbers are the average of horizontal and vertical readings in each corner) for each type of lens from wide open to f/11 on 5D Mk II cameras. The Canon is shown at both f/1.2 and f/1.4, the other two, of course, start at f/1.4.



The Zeiss corners peak a little earlier than the Sigma (at f/4), but at f/5.6 resolution for those two is virtually identical. The Sigma corners are even a bit better at f/5.6 The Canon hangs with the other two lenses in the center, but its corners never sharpen up quite as well as the other two do.


I really don’t have a lot to add to what has already been said. From a resolution standpoint the Sigma is nearly as good as the Zeiss Otus, and clearly better than the Canon 50mm f/1.2 L. It does this at a price point far lower than either of the others. There may (or may not) be some sample variation, but I won’t know for certain until we’ve tested a lot more copies – but even the weakest two copies of the Sigma were clearly better than any of the Canon’s.

Of course, people buying wide aperture 50mm lenses are at least as interested in bokeh, autofocus accuracy, color rendition, and a number of other traits as they are in resolution. More and more images are being posted every day to let you assess that before making a decision. But assuming those things all turn out acceptable to you, it’s hard to imagine a better value at 50mm than the Sigma 50mm f/1.4 art.

Roger Cicala


April, 2014

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. 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 Other
  • alex

    Dear Roger,
    I own Sony, now I have sony Zeiss 24mm f2 and 135 f1.8
    Am try to decide between Sony Zeiss 50mm 1.4 and Sigma 50mm 1.4 ART
    Do you have plan to test it?

  • David

    I must fully agree with Roger on one of his earlier comments: Owning a Sigma of the current series (A/C/S) simply obliges to buy the dock as well.

    Despite all the good new lenses Sigma currently throws out on, this is probably there best invention in this whole new line-up.

    The money is definitely well spent!

  • Roger Cicala

    George, I wish they had added that because it would be huge. It should be fairly easy to do, but I think it would be done in camera, rather than lens, processing, although I could be wrong about that.

    I also suspect for most lenses they’d have to limit a ‘focus shift compensation’ to center point or it would get rather complex: off axis the focus shift can be quite different than it is at center. It could be done, of course, but I think the algorithms and tables would be fairly huge and that definitely would have to be in-camera, since the lens wouldn’t know which focus point was chosen.

  • Roger, would you elaborate on your comments on the Sigma USB Dock? I’ve purchased one, and it can do fine tuning for different subject distances (probably useful, though I tend to shoot in the same range, and do my AF fine-tuning at that range), but it doesn’t do tuning for different F-stops – and I have very large focus shifts as I close the lens down from F1.4 to F5.6 (Sigma 35mm F1.4, as well as my other Nikon F1.4 primes) Now, that would be useful – so far, only Hasselblad has acknowledged focus shift, and built in-camera firmware compensation for it – it’s such a simple fix, why don’t any other camera makers provide it?

  • AJR

    I’ve ordered the Sigma, sight unseen, for my D800e. I tried Nikon’s 50mm f/1.4G and was very disappointed. I have to have auto-focus, so this looks good to me.

    No one else does the multi-lens samples like you do, and it is very much appreciated.

  • pj

    Would be great to see the APO-Summicron rated in this comparison at some point.

  • BrunoS

    Roger, would a D7100 show more on the resolution?

    Thanks for this wealth of information.

  • Brian B

    Hello Roger,

    Any chance you could add an MTF chart to this post? The graphs are great illustratively, but I love data!

  • NancyP

    Thank you very much for the multiple-copy testing, Roger. That is reassuring.
    Here’s a Korean review that includes photos testing bokeh, coma, etc at various apertures relative to the Canon f/1.4 : http://lcap.tistory.com/entry/Sigma-50mm-f14-dg-hsm-Art-Review Bokeh and coma look very good based on this review and lenstip review and tests. I would not consider this lens to be an ideal candid/ “street” lens, it is on the long side and would be more conspicuous than Canon 40mm, 35mm f2 IS.

    THe point is well taken to get and use the Dock and favorite testing kit. I have yet to do so for the Sigma 35mm f/1.4 Art because most of the time I use manual focus, live view.

  • derek

    the huge barrel size alone makes the Otus impractical to me , but if you accept the size and weight , then go for it. I had the 135mm APO Sonnar but I sold it due to its huge size and extremely low keeper rate I got with the lens. But it was a 135mm tele prime , so I could accept the size if I had to but this is 50, the size really matters since for me a 50 is always street lens.

  • Nqina Dlamini

    Thanks for the article.
    I’m also thinking of getting the Art to replace my Canon 50 F/1.4. I know its nearly twice the price of the F/1.4, but the prospect of getting the F/1.2 performance (not to mention the solid build and near Otus performance) at almost half the price is tempting (one can always dream).

  • Grant

    Aw gee, where’s OLAF when you need him? 😉

  • Roger Cicala

    I will try but the next few weeks are pretty crazy.

  • Roger Cicala

    Sean, I can’t say because they were tested on completely different camera bodies. It will be interesting to compare when we get our optical bench running in Sony mount, or when Sigma releases the 50mm Art in Sony mount.

  • Roger Cicala

    James, I do plan to do that test. I think the D800e sensor might show some differences that the 22 megapixels don’t show – I expect both the Sigma and Otus will be better, but the changes might surpise us a bit.

    Pieter, yes the bodies do affect things which is why we always use the same cameras for testing.

  • Great job !
    Well done Roger.

    Very informative and straight to the point !

  • Carl

    Roger, excellent work as usual! Your results help confirm that of others. In particular, Bryan’s test sample crop images tell the tale pretty well, in my opinion. In those (you’ve likely looked), the Otus appears noticeably sharper at all apertures than the Sigma, except in the corners at f/5.6, where the new Sigma clearly wins. Of course I think his test was only one copy, so tests of 30 copies would be vastly more representative. Clearly the Sigma is now the best “fast aperture” lens value at or around 50mm, at least if sharpness is more important than bokeh smoothness. From what I’ve seen, the Otus and Canon have smoother bokeh, but I admit I’ve not seen enough, and could be wrong.

  • James Scholz

    Thanks Roger, I too have been waiting for your tests and appreciate this one.

    I also wonder about the sensors and hope you do a similar test with the Nikon D800e when the Nikon version arrives. I suspect the curves will be relatively similar, but there might be some surprises.

  • Hello Roger, about the results i see here ;

    Are the results related to the resolution of the camera body? (- a Canon i guess)

    ( If that is so i would very much enjoy reading about a lens test without being hampered by the body)

  • Hi, thanks for comparison.
    I would like to ask you, if you could test against new sigma 50 1.4 A, old one sigma 50 1.4.
    What I have seen, differences are not so big, to have reason for upgrade soon.


  • So, is the Sigma 50 the best AF lens you’ve ever tested or is it the Zeiss 55 in FE mount for Sony? Neither?

  • L.P.O.

    I don’t really have very much to add except for a thank you for testing several copies. No-one on the web is capable (or willing) of doing that, so even though you don’t provide full reviews, you give us a unique insite to some lens aspects. This, while far from replacing complete reviews – really adds to them. So thank you again for this valuable service.

    Loved “After using those, the Canon’s manual focus ring feels like a greased pig.”

  • Roger Cicala

    Jim, I don’t. I only shot it on a 5DIII which appears (from what I read) to be a camera it works well with. But I will say most of the comments I’m reading are by people who don’t have the Sigma dock and haven’t adjusted the lens on it. My opinion – buying a Sigma Art lens and not owning the dock is basically trying very hard to fail.

  • Jim Thomson

    Roger, Any comments on the autofocus issues that have been reported?

  • Darkman

    What I do not understand is why you compared with the Canon f1.2? Reading other tests as photozone, we know that sharpness is not one of its strengths. I had the opportunity to try a copy of the f1.2 myself and I confirmed that it has less sharp center and boundaries than my f1.4 at all apertures.

    Thanks for this nice and interesting read, as usual.

  • Roger Cicala

    Weilly and Carvac – I actually tried it. The graph looks better but the MTF50 values become very approximate and difficult to differentiate. Then I added numbers to the points and graph got very crowded. I’ll look into some other methods, or maybe show both.

  • Definitely not “yet another”. In fact, the one I’ve been waiting for, to see if the thing is as good as everybody else says. I’d be begging you day and night for these numbers if you hadn’t posted them.

    Of course there’s other stuff to a lens apart from sharpness, but sharpness is very important. You’re the only one who tests several copies, and your regular readers know there’s a lot of value in that. Looking at your graph here, a site could be saying the Art is just as good as the Otus, and another one could be saying it’s slightly better than the Canon but clearly not as good as the Otus, and they both would be right. Only you tell us how that can be.

    My point is: thanks for posting, you rule.

  • Joachim / CH

    “being late at the party” – if it’s of any comfort for you, Roger, a lot of party-watchers including me were waiting for you, your kind of writing and your great possibilities of comparing a batch instead of only one sample and not only a choosen copy for early test-labs to blow the hype 🙂

    Although in Sigma’s case, it could become a problem of delivery time if they increase the hype on purpose. I’m a bit surprised of the variation range of the Sigma and I see the Zeiss workers are doing the best job – of course, at that price and with the disadvantage of “no AF” everything else is not acceptable for customers.

    A couple of hours ago I updated the Sigma USB dock software and firmware. It now has a Switch for “Everytime Manual Focus” which was invented for the 50mm. I wonder what it will do? Anyway, the Nikon versions are announced for end of June, then I’ll find out.

    Thank you very much for sharing the results and your conclusion.

  • Weilliy

    Suggest that you might use exponential-2 as X-axis which will emphasize aperture the normal perspectives we use

  • CarVac

    Those are some pretty loopy curves. You need to put them on a log scale to make them more comprehensible… (perhaps even log-log)

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