Canon users rejoice there is a new option for a fast 50mm lens. It falls between canons top two offerings, the 50mm 1.4 and the 50 mm 1.2 L, in regards to price. However in image quality it is in a different league.
If you just want to know if the lens is worth buying, then yes it absolutely is. It is super sharp wide upen, has great contrast, focuses quickly and is probably one of the most versatile focal lengths available.
I really only had one hesitation in purchasing the sigma, its size and weight. The thing is huge, it is the same size as my L series 24-70 f2.8ii and just as heavy. So if you are looking to have a compact lightweight lens to walk around with then the sigma is probably not going to be your first choice. However if you are looking for maximum image quality without taking a loan out to finance the even larger Zeiss Otus then this lens will do exactly that.
I have tried Several copies of the Canon 50mm 1.2 and could never commit to purchasing one. I always felt that it was slow to focus and not very reliable. It also wasn't very sharp until stopped down to 1.8 IMO. With a price tag of almost $1,600 I felt it wasn't worth paying for a 1.2 aperture when I wasn't that happy with the images until I stopped down the lens. So I started researching. At first I was occilating between three lenses, the Canon 50mm 1.4, the original Sigma 50mm 1.4 and the Sigma art 50mm 1.4. It didn't take long to eliminate the Canon with its overall softness until it was stopped down to f2.8. Then it came to the two offerings from Sigma. The original lens had its fair share of praising reviews about image quality but also quite a few complaints about front/back focusing.
So I decided to rent the new Art lens from the great people over at lens rentals. I timed my rental with an engagement shoot I had scheduled to get a chance to try it out on a real life shoot. Once I started shooting I could tell from the back of my 5D MKIII that it was looking awesome. The colors were vibrant the images were super sharp and it was focusing quickly. I kept shooting with the lens and before I knew it the shoot was over and Marc and Sarah were asking me to fly to Costa Rica to photograph their wedding. I was super excited to be going to Costa Rica with them and I couldn't wait to get home and see what I got out of this lens on the big screen.
As soon as I downloaded the images I kept getting more and more excited about what I was seeing. All of my favorite images were shot with the Sigma. The focus was tack sharp (providing I did my part) and the color/contrast were amazing. The 50mm Sigma Art at f/1.4 performed at the same level as my Canon 24-70 I I at f/2.8 which is bitingly sharp. The main difference is the extra two stops of light you get from the Sigma and the awesome subject isolation from its fast aperture.
The Sigma Art performed flawlessly, my only wish is that they could have done it in a smaller lighter package. After 8-10 hours shooting a wedding every single ounce counts. Experience has taught me that "ounces equal pounds and pounds equal pain", unfortunately for me the Sigma is just too good of a performer to pass up. It's probably the most useful focal lengths, IMO and has superb image quality. Until someone comes out with a 50mm that performs this good in a package that is half the size this one is staying In my camera bag.