Sigma Art lenses on SIGMA CAMERA? No one has tested that?

With all the spin about the Sigma Art line, most recently the 50mm flavor, no one has yet objectively tested a Sigma lens on a Sigma body. Or if they have i cant find it anyway. TDP's review of the lens for Canon bodies was certainly one of the most anticipated, and is currently the most frequently referenced respectable review on the web.

The TDP review made one observation in particular; that the lens focused erratically. Readers have attributed this to the supposed difficulty of a 3rd party lens maker in getting the lens to communicate with Canon bodies.

This, I think, raises one big obvious question then. "Would the Sigma lens focus better on a Sigma body in the same testing setup?"

Since TDP authored the original widely-read test on the Canon body in which the autofocus issue was observed, I really think people would be very interested to see TDP in particular run a follow up test with the lens on a Sigma body. It would certainly be widely read and often-cited in the endless back and forth in all of the camera forums. It might even prove, or disprove, that hypothesis on autofocus issues being caused by mixing two manufacturers' products.

I am taking the lack of replies not as disagreement but as silent acknowledgement that my assertion is so self-evident that there is no need to add anything to it. ;).

Seriously look at other forums like CR and this really is a pretty hot topic and an answer to that question would definitely be eagerly read and no doubt much-used in discussions.

Hi Scott,

That is an interesting concept, one I have wondered about as well. One would think that Sigma could completely tune their system for optimal AF performance. I'll give the test idea consideration.

Thanks,

Bryan

Sigma has camera bodies??? ;)

Ok, seriously, the test you suggested and Bryan is considering would be interesting, but it would mostly be academic for me as I shoot with a Canon body and have no plans to switch to Sigma. Also, you might learn if the AF performance is better, but you might also not learn anything at all. First, is there even a quantifiable issue that has been identified? Is there only one "issue?" Even if you could quantify the issue, is it repeatable? And, with all of those, the issue could fall into one of three categories, two of which may not show any difference in the test---1) Software issues arising from the reverse engineering of Canon's AF protocols; 2) Hardware issues that would impact any and all camera bodies; 3) Software issues that would impact any and all camera bodies (i.e. the way Sigma programs their AF is inherently inferior).To make this more complex, is it just certain Canon bodies, or is it all of Canon’s AF protocols? Lenstip.com observed an issue on the 1DsIII, but not the 5DIII or 50D.

So, it isn’t a simple issue, but considering how many people are also happily shooting with the Sigma lenses, I do wonder if it is a bit overblown. Ultimately, every lens is a compromise. Part of the Sigma compromise may be an AF that isn’t as good as Canon’s best. But,I’ve tried to look at it myself, and from what I can tell, it is on par with Canon’s “mid-tier” AF lenses (50 f/1.4 and 24-105 f/4 IS) in terms of overall AF speed. But, I perceive the way they get to that overall speed as different. The two Sigma lenses I have seem slower to initiate but faster to settle, whereas Canon’s are typically fast to initiate but slower to settle. I've wonder if this phenomena, if correct, is the actual cause as Canon's "slower to settle" is actually refining and verifying the accuracy of the AF where Sigma simply gets you close.

As I shoot with the lenses, I will report back if I find something. But so far, the 35A is much better after as econd AFMA and the 50A has been very good from the start. I did buy the Sigma dock, but haven’t yet used it.

In the end other factors are likely weighing in on the compromise more than AF for me. I’ve tried to love the 35A, but I am about 80% of the way to the conclusion that I don’t love it enough to justify the cost and its place in my bag. It may be a casualty of some other recent purchases. It isn’t because of the AF, but rather I am not sure I use the 35 mm focal length enough to justify a prime lens. If it had less vignetting at f/1.4-2, I could maybe use it more for nightscapes, but it has significant vignetting.

On the otherhand, so far, the 50A seems to be a keeper.

EDIT: thinking about my perception that the Sigma is slow to initiate and fast to settle with the Canon being the opposite. Thinking about that more, wouldn't the "settling," if it is refinement of the AF accuracy, be controlled by the camera body and not the lens? I'll try to test that perception more soon.

Thanks for chiming in, Bryan. I always appreciate your site.

Kayaker,
I see some of your points, and true, since you would be comparing different examples of the lenses on different bodies, there could be an opportunity for sample errors to creep in if any piece of the equipment is an unusually poor copy, but the comparison would still be interesting. People on this site and others compare image quality between Canon and Nikon setups, and look at 3rd party Sigma, Zeiss, etc. lenses on Canon bodies, and even Franken-foto combos of Nikon glass on Canon bodies with adapters attract morbidly curious glances.

Here, though, you see forum threads all over the place where people are wondering, and sometimes presuming to know, whether the Sigma 50 Art focuses erratically on the TDP Test because Sigma can't create a lens that autofocuses consistently under any circumstance, or whether it is it a problem in getting their hardware/software to work without bugs with someone else's hardware/software?

Scott,

Don't get me wrong, I'd find the test interesting...along with possible results on Nikon and Sony bodies. It would have to be enough use to really see if problems developed. As Bryan noted in his review, even what he saw was inconsistent. Maybe you've seen, but Eldar did ask those on Nikonrumors if any of them had problems. Most hadn't yet received the 50A at that time, but I read through the thread this morning and I didn't see any mention of AF issues. Mostly statements like "new favorite lens" and "best lens for the D800E."

But it would be interesting to know if this is mostly a Sigma/Canon issue or not.

That said, right now I am basically assuming that there are multiple "issues" including copy variation, 3rd party AF issues with Canon, and perhaps inherent lower build quality in comparison to Canon. All that said, it is the third 50 mm prime (50 f/1.8, and 50 f1/4 being the others) I've owned and easily the best (AF and optics). I have yet to have any issues, and am pleased with the AF. I tried to recreate Bryan's test and did see some issues, but not a 40% miss rate. I also tested some Canon lenses at the same time and most were a little better, but the worst performing lens wasn't a Sigma, it was my 100-400L. Viggo and Eldar both reported over at CR that their issues developed over time, Viggo's at ~2-4k shots. So, we'll see. With me, so far, so good.

Have you had any issues with your 35A?

Thanks,
Brant

I don't often go to Nikon Rumors, but it is interesting to be reminded how the 3rd party lenses are being used and discussed by a whole different group of users than the Canon world. I do go to Sigma Rumors but they don't do any testing, but rather refer you to sites that do testing, including this one.

I have zero trouble with my 35 Art. It focuses reliably and I just love the thing more and more after about 8 months with it. I did play around with it and did a little home AFMA on it. I ended up giving it a +2, but it really hadn't been crying out for a correction or anything, so I don't notice much real difference.

At the time I bought it before Christmas I had been waiting impatiently for the 50mm for a while. I really didn't think I would like the 35mm length or the potential for facial distortion s up close, but I must say I have changed my mind. The distortion is minimal and easily avoided by staying a few extra feet back, and the wider FOV is handy with small groups indoors in dim light, like at dinners. I have had some fun at the local Hibachi table restaurant in particular. My little girls had zero idea the table would burst into flames, so I was ready to catch their reactions when it did. :). Ah, good times.

The Sigma 35mm f/1.4 Art continues to be my go-to lens for indoor events. Partly because of the focal length, partly because it's a really good performer in the IQ department. That said, the Sigma 50mm f/1.4 Art is a lens I would be happy sticking on my camera and not taking off for 3 months. It's an unbelievably good lens. As long as a 50mm focal length suits the situation, it'll be on my camera.