The Sigma AF 12-24mm f/4.5-5.6 HSM DG II is the only "one size fits all" (formats) ultra-wide zoom lens on the market. It can give you decent results and truly extreme views on full format DSLRs and it is very good along across the more "conventional" zoom range on APS-C DSLRs.

Given the high bar set by Sigma's Art lenses, when I first heard about Sigma releasing this lens at a fairly affordable price I was extremely excited. Unfortunately though, the lens fell short in several aspects.

Sigma unveiled its third generation wide-angle zoom lens, the 12-24mm f/4 DG HSM Art lens, on 16 September, just before Photokina 2016. A significant update to the 12-24mm f/4.5-5.6 HSM DG II model, it comes with Canon EF, Nikon F (FX) and Sigma SA mounts.

The Sigma 12-24mm F4 DG HSM Art is a fantastic ultra-wide-angle zoom lens that significantly undercuts the price of its main rivals whilst offering almost comparable image and build quality. Image quality is excellent.

I have been using the generation one Sigma 12-24mm lens for wide landscapes and architectual shots for many years. The older lens was sharp in the center but soft at the edges and corners even when stopped down. The older lens was at its worst in the 12-15mm range, right where you needed it most.

I love this lens. I love it for promo photos, realestate , and even group photos. The only thing is I thought o was buying it in Canadian dollars and it ended up being U.S. prices. Ouch.

Agai, lack of Sigma's QC: i bought one second hand, but this lens is a lemon, you can throw it away. The lens was soft overall no matter what i used, really bad till f7.1, from f8 till f22 was overall soft.

nothing

lack of Sigma's QC; lens is soft overall; slow AF

This is the ugliest imaginable lens... Sorry, but had to say that and get it off my chest. It just looks ghastly on my Nikon F5 and on the F100 too. Oh, well, now that I said it, I should add that it's a very good, reliable tool. Where does one get a wide-angle this wide Nowhere!

Speed, size and relatively discreet look (if it wasn't for that front element that's downright bulbous); Nice range of focal lengths

Maybe it's ugliness, along with that the front element is so weird looking and doesn't allow for filters of any type; Other than that, it's not a lens to use with flash 'cuz it vignettes like mad, especially at 12mm (and what's the fun of using a flash at 24mm with this lens None.

I have owned this lens for about nine months now and have used it for both bird and mammal photography. I sold the Nikon 500mm f4 that I previously owned and after much research, eventually bought this one. I was much influenced by the superb testing of this lens by Canadian photographer Brad Hill.

Durable; Great Features; Great Picture Quality

Bulky; Heavy

If, like me, you're accustomed to edge-to-edge sharpness and couldn't bring yourself to even press the shutter-button, with the expectation of chromatic aberration, with it's purple-fringes, then this lens is for you.