I just received a Sigma 19mm/2.8 in E-mount. This is the second time I have ordered one, the first time I was sent the lens in micro 4/3 mount. Luckily this time I got the lens I actually ordered. I can see why other people have been very positive about this lens, it is very sharp, even wide open. The build is reasonable and though not as small as the 16mm/2.8 pancake, it is still not an imposing optic. I took it out for a spin today in Glasgow City Centre to test how well it focused and whether there were any issues with using it as a street lens.
The AF speed is moderate, not very snappy but with some practice quite usable. I feel the 16mm/2.8 actually autofocuses faster but I have not done any direct comparisons under the same lighting conditions. It was getting a bit overcast, grey, and dim this afternoon though so it was a test of the Sigma. I just have to adjust my technique slightly to anticipate when I want to release the shutter and give some extra time beforehand for the lens to focus. The AF speed is also a function of the camera body (NEX-7 in this case), perhaps the NEX-6 may be better (or worse). I wonder if Sony will update the firmware to allow PDAF on that camera with non-Sony lenses such as the Sigma 19mm/2.8.
One thing I have noticed is that they aperture mechanism does make an audible click, really only noticeable when it is quiet. You can hear the aperture opening and closing as you focus in you are not shooting wide open. On the street it’s not an issue, and especially insignificant compared to the shutter sound.
All in all, I am very happy with this lens so far. I shall have to test it for landscape use but I think it should resolved quite a lot of detail across the frame when stopped down. I shall also be looking to see if there are any colour shading problems in the corners.