Excerpt: Image quality on the Sigma 30mm f2.8 is nice for a lens in this price range. Looks great and is compact. However, there is no manual/auto focus switch on the outside, which means you can only switch between the two in-camera. So, don't buy this if you're planning on using it with the Black Magic Pocket camera. Some people report that it works fine with their pockets, but it definitely did not with mine.
Pros: Easily Interchangeable, Lightweight, Nice image, Strong Construction
Summary: I own the newer, silver version of this lens. I run it primarily on a Sony Alpha A6000. By now everyone knows the good... it is a good value, prime lens for your e-mount Sony body. For the price, you will have to go with an older adapted manual for anything sharper. For what it is, it is wonderful. The drawbacks... ** It can be painfully slow depending upon lighting. So much so that if I am shooting a portrait, I grab a manual 30yr old 50mm prime / adapter.
Summary: Ordered this in advance of a convention I wanted to document, got the lens in, initial tests seemed ok. But when I got to the convention, within the first day just shooting some portraits the focusing motor malfunctioned, and then the lens completely bricked. Neither camera I tried it on, Lumix DMC-G5 or Olympus E-P3 would recognize there was a lens attached.
Excerpt: Love the lens for photo crispness. It's rated better by the photo experts, which I am not. It works well on my Sony NEX-7 camera and is the equvalent of a 55mm lens. Nevertheless, the big downside is its lack of internal stabilization for the NEX cameras which do not have that. Others who have perfected the technique for taking still pictures while walking around may not see that as detrimental.
Summary: Good sharp lens but need and should have been faster. With Sigma's know how it should have been a f1.2 or f1.4. Focus is sharp on my E-M5. I still don't understand why for what you spend on quality lens, they don't come with hoods.
Summary: I've been using this lens for a couple of months now and I found that the autofocus is even slower than the kit lens. It does take sharper pictures and the depth of field is nice at 2.8. However, there is a one major flaw in the design. The focus ring is made of a very slippery metal ring that gives you no grip whatsoever. It's not an issue if you're using it indoors, but outdoors when it's cold out it is difficult to get a grip.
Summary: I own 2 other lenses, the Panasonic 14mm pancake and the Olympus 45mm. Of the 3, this one is the worst optically, slightly worse than the 14mm and much worse than the 45mm. Pictures show significant Chromatic Aberation and a general lack of crispness/contrast (similar to the Sigma tele 70-300 I have for my Nikon D200). I don't mind the rattling. Overall decent value for the money but optically a bit of a letdown - 3 stars.