Even though this thread is old - still I'd like to contribute.
To me as someone doing mainly landscape and city photography the Sigma 19mm is a bread and butter lens. It's your standard wide-angle lens (fullframe: 28mm) which might sound boring but quite often you simple need that angle.
The lens is very sharp, especially when closed to F 5,6/8, yields great contrast and on the Alpha 6000 I never experienced any problems with AF (I use the older DN version before they called it ART lens). Compared to the Sony Zeiss 24mm (SEL24F18Z) this lens doesn't have that level of micro-contrast but in post production you simply can add a certain amount of clarity to it. By the way: IMOHO Capture One has a really great lens profile for this Sigma lens.
One downside of this lens might be CA which can be visible in certain situations but is usually very well corrected automatically by Capture One.
But the biggest pro argument for this lens is its size. It's small and light and therefore perfect for small APC cameras. As I usually conquer cities and countrysides by foot weight and size is an issue. And for landscapes 2,8 is no deal breaker and you can use this lens even wide open.
To sum it up to me this lens is all thumbs up and I would not want to live without it - indeed I love it. With a price tag about $200 it is really good value for money.
All pictures are taken with a Sony A6000, Sigma 2,8/19mm EX DN
Dornoch Beach, about 60km North of Inverness, Scotland, F16, still usable closed so far down, see whether you can spot those people with their dog in the background:
Not to worry, I think it is good to keep these showcases alive. Photography sites as a rule tend to dwell on either recent or vintage gear. Solid products a few years old seldom get attention. It is good to be reminded you often do not need the lens everybody is all GASsy over when you can save some cash while getting a good product from just a few years back that is made from your camera.
Otherwise, I'd love to have me a Sigma f/2.8 16mm! Too bad Sigma didn't make such a little beast. Their line up of f/2.8 Arts could've used a 15-16mm and a 24mm to round it.
Great images added to the showcase. I also have the same version of this lens, and it's done nothing but return very sharp and satisfying images while shooting street or landscapes. Some of my favorite shots from it are posted to a thread discussing the characteristics of this Sigma 19mm. I'll have to link it to here.
Ah thanks, missed that one. Just corrected it.
I totally agree with you, instead of going 1,4 with their C-Lineup Sigma shouldn't have lost focus on their 2,8 Art series. Such speedy lenses put on a lot of weight and size and IMOHO are not necessarily needed as a wide-angle variant.