Summary: I bought this lens for my Sony NEX-5R, but I was severly disappointed. I initially could not resist the $129 price tag and I thought I saved quit a bit over Sony's 16mm or 20mm lens. I had a Sony NEX-C3 with a 16mm lens and thought it was pretty good. I don't like the size. It makes the whole camera too big to carry around and I probably drop it from my hand or shoulder sooner or later. I don't like the lens design.
Lens frequently freezes at out of focus and requires power cycle
28 December 2012
Summary: This lens frequently freezes at out of focus state and I can hear the crank noise but no matter how I press the shutter button it just stays at out of focus. Every time I end up power down and up the camera to bring the lens back to normal operation. To reproduce the problem, you can shot at a 20cm distance away object in DMF mode. The lens becomes freezing at out of focus once you adjust DMF.
Summary: Received the lens today. Build quality LOOKS good, but it isn't. There is something loose inside the lens. If you want to know how bad it sounds, put a quarter into a cup, and shake the cup around. The lens starts clicking if you tilt the camera up or down. You can also sometimes get clicking when you auto focus. Other times it is dead silent. I've heard the same issues from other Sigma 19mm and 30mm users, hence the 1 star.