I have a confession to make. It won't seem like much because I've made it here before but...here it is: I don't like wide angle lenses. They are unruly and they take in too much useless scenery. But I've found one that I like enough. It's the Sigma 19mm lens for the Sony Nex cameras. Someone at Sigma did their homework and made a lens that is sharp, cheap and works well on what is a notoriously difficult sensor for a lens to please. As I understand it light rays need to be collimated as close to a straight perpendicular as possible to image the light wells on the sensor correctly. The sensor doesn't handle tangential light rays well. Apparently someone at Sigma incorporated this into the design of their recent 19mm and 30mm lenses.
The 19mm yields the same angle of view as a 28.5mm lens would on a full frame, 35mm camera. Wide enough for me but probably too long for real wide angle afficionados. The 19mm is one of three lenses I took with me on a recent trip to Boston. I used it whenever I wanted a wide view. After a while I noticed that I was using the 50mm OSS Sony lens and the 19mm for nearly 100% of my shooting and I'd been ignoring the 30mm Sigma lens that I presumed would be my "go to" lens because of it's equivalency to my normal favorite focal length, the "normal" 50mm on a full frame camera. Funny how lenses and formats can change your preferences.
From what I've seen the 19mm is very sharp, even at its widest f-stop of 2.8. Many photographers immediately state that they must have all their wide angle lenses be as fast as possible and I get it. That's why I recently picked up the Rokinon 35mm 1.5. But if we are being rational we'll probably come to admit that a lot of the use of a lens in this focal length class is for snapshots and documentation and a lot of that is done in fair to good light. The trade off for faster glass is size, weight and price. You get all three when you go faster. It's not a case of "choosing one..."
If our goal is a lightweight, high performance travel package then the 2.8 aperture makes a heck of a lot of sense. I happily bought the lens at it's full price of $199 but in the ensuing months there have been temporary price drops to as low as $100. The price seems to have stabilized at around $150. If you are shooting raw you'll find a profile in Lightroom 4.4 for this lens that corrects for its geometric distortion. What you end up with is a sharp image from a relatively tiny package.
After using the 19mm for the last few months the only drawback I've found (with the Sony Nex cameras) is the lack of image stabilization. If you use the m4:3rds versions you'll find that the OMD does a wonderful job stabilizing the image and giving you the feedback you want in the EVF.
My hope, in terms of future development from Sigma, is that they make available whatever lens formulation they are using for the Sigma DP3 camera. It's a dedicated 50mm 2.8 and from the samples I've seen all over the web (including sites I trust like www.luminous-landscape.com) it's as sharp as the Leica M series 50mm with which I used to photograph. If they can make this available in both Nex and m4:3 mounts they'll have a new cult super hero lens on their hands. I'd line up to get one. Especially if they keep their pricing in line with the 19mm and 30mms.
Boston is a fun city to shoot in but perplexing. Even though there are tons of great things to photograph (both people and buildings) I've never seen a city with fewer photographers rattling around on the streets or in the museums and public spaces. Is Boston just totally over photography?