I hear and read so many stupid things about this lens that it’s time to do it justice. And by the way, do all these people reviewing lenses and spending their nights online commenting on forums actually own these? Have they even ever touched them? I don’t think so. And even if they do, it looks like they’ve only been shooting test charts… So watch out, this is a review from a photographer who’s been using this Sigma for years and who is shooting anything but test charts.

Let’s look at what most “online experts” complain about:

• Useless because distortion is huge : Are you serious? This is actually the best feature of this lens : distortion is almost  non-existent at all focal lengths! I guess these people mix up distortion and perspective… Again, straight lines will remain straight with this zoom. Keeping vertical lines vertical and horizontal lines horizontal is another story… It requires a lot of walking and moving around to achieve both. Hand-held, it’s a nightmare. This zoom is so wide it requires very precise framing. You have to look though the viewfinder for long minutes, paying attention to all details, before shooting. Our brains are not used to focus on 122°, but when it comes on paper or screen, every little detail catches you eye immediately. Trust me, it’s less obvious than you think. It has nothing to do with the quality of the lens however, it’s the extreme angle covered that makes this difficult.
• Sides and corners are soft, falloff is visible, even on APS-C body : First of all, this lens is meant to be used on full frame bodies. It is actually one of the reason why I decided to get a full frame DSLR. There are wider, cheaper and maybe better alternative for  smaller sensors. The only reason you’d want this lens on an APS-C camera is because you already know you’ll buy a Fx body in a near future. I first used it during the Nikon Dx era when Fx DSLR didn’t exist yet, and now that I’m back to full frame, I’m glad I made this choice. Having said that, some falloff and softness is indeed visible wide open on a full frame camera, but it’s so far from the center it’s way out of the Dx area. I never noticed anything like this with my previous Dx camera. On a full frame camera, I can live with it.
• The whole picture is so soft it’s useless under f/11 : I get very sharp results even when shooting wide open and printing 30×45 cm. I don’t fight for more sharpness beyond this point, especially not because I’d like it to look better on a 100% crop on a monitor. Final print is what matters.
• Can’t use it with a polarizing filter : Why would you want to use a polarizing filter on a lens covering and angle as wide as 122°? You’re not going to be polarizing half of the frame anyway. Ok, maybe it would be nice to put a protective filter in front then? No way, depth of field is so big that any dust on a UV filter would be in focus on your images. By the way, none of the full frame ultra wide lenses allow filters screwed on front (see the new Nikon 14-24mm f/2.8, the Nikon 13mm f/5.6, the Nikon or the Canon 14mm f/2.8). Don’t compare this lens to a normal 16-35mm, this is a ultra-ultra wide lens. There has to be a price to pay.
• It makes the AF go crazy : I never experienced anything else than fast, focus is dead on with my Nikon’s. I can’t tell you about Canon, but I suspect a problem with the AF of  body, not the lens.
• Images are flat / no contrast : Again, the angle is so wide it is difficult for the camera to choose the correct exposure. I apply exposure compensation most of the time because the meter gets cheated by the big bright sky or the big dark area you’ll almost always end up with. This lens must be very difficult to use on film, without instant review and histogram. Once properly exposed, contrast is excellent.
• So slow it’s useless for shooting  indoors: Any newer Fx camera has an insane ISO range and you can shoot at 1/15 without worrying with this lens.  I never use a tripod. This is not a lens I use for freezing movement. I do the exact opposite: keep the background sharp and have movement in the details, so I don’t really need faster shutter speed.  Ok, 2.8 would be ideal, but how much would I have to pay for the extra?
• Sample variation : There seems to be an urban legend around being lucky and getting a sharp copy or not. I usually don’t buy this stuff. Of course I only tested mine and never compared it to someone else’s so I can’t tell. Still I think it’s entirely made up online in the forums, by people who have to find a technical reason behind their crappy pictures instead of questioning their own abilities. Anyway, I’m very happy with mine.

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For the rest, build quality is great, zoom and focus rings are smooth and precise, flare and ghost are (surprisingly) not a problem. I like when nothing moves or turns on a lens (exept the rings of course), which is the case here. It’s all internal focusing and internal zooming. A big plus to me. I almost forgot to mention it’s an HSM lens, meaning it focuses quietly and allows instant manual focus override.

So is it perfect?

The only competitor I can think of is the super-expensive Nikkor 14-24mm f/2.8, which is so expensive I don’t even dream about it (both Nikon an Canon also manufacture a fixed focal length 14mm f/2.8 in the same price range ). For 3 times the price, you loose 8° and you get 2 stops faster. In my opinion, it can’t be so much better that it justifies the price difference. The Sigma is not perfect of course, it’s an extreme zoom and some compromises had to be made… But it’s also the widest of all wide-angles on the market and it’s opening new creative fields. It’s not an “easy to use”,  “point and shoot” midrange zoom, but if you are willing to invest some time in mastering the beast, you’ll be rewarded with great and original pictures.