I recently posted about my miserable Sony 16mm for the NEX. You can see
sample images and crops here. I ended up returning that POS lens and picked up the Sigma 19mm f2.8 lens for NEX. I did the same series of shots as I did with the Sony 16mm for comparison.
Here's the lens at f5.6
And at f2.8. What a huge improvement over the Sony.
I tossed my Nikon 24mm t/s on there to compare. Here it is at f3.5
And here's the Nikon 24mm f1.4 G at roughly f2.8 (I'm using an adapter with no f scale on it. The shutter speed was the same as the Sygma lens at f2.8 so I think it's safe to say I was at f2.8.)
Obviously, this isn't a scientific test. But the $200 Sigma doesn't fare too poorly against lenses that cost ten times as much. In any event, I'm happy with the results. 28mm (effective focal length for a 19mm on a 1.5 sensor crop) is my favorite focal length for PJ work. Plus the Sigma has AF - manually focusing the Nikon lenses on the NEX takes time and it's not easy to nail. Okay for a still subject, not okay for rapidly moving subjects - which most of mine are.
John
