Well I finally got my self anther prime :-) I´ve been a patient owner of a kit lens and a 50mm f/1.4. I was not totally unhappy with the kit lens but wanted a faster wideangle lens mostly because the 50mm is a bit close for indoor shots (on my 300D) and I figured I hardly put the kit lens on unless taking landscapes and stepped down too.
I bought a used but mint Sigma 20mm f/1.8 from a guy here at the Buy/Sell forum for not much less than a new one. i felt more secure about getting a good copy that way since I'm not shure I can get warranted repair here in Iceland.
My first impression was quality. The lens it self is big and heavy at least compared th the 50mm f/1.4. The exterior finsh feels rugged and the focus ring is smooth. Sigma gives you a padded green bag for it and a lens hood. The only thing I don't like about the exterior of the lens is the fact it is a bit gray-ish compared to my black 300D (but that's me just being a bit gay-ish). The only real downsides I can see with ergonomics is the big (and expensive) 82mm filter size and noisy zoom.
I did not do any ruler or bookshelf test because I don't care for them. Instead I just took the camera with me to the beach (yes, we actually have a beach in Iceland) after work and did some car shooting for my work this morning.
The lens get's thums up from me. Those who report this lens being unusably soft at f/1.8 must have a broken lens. From what I see f/1.8 is quite useful. Maybe I would see something if I got a Mark II or something??
Why did you take pictures of my car ? Just kidding. Nice shots! Are you using a 1.6X camera for those images though? The corners on a FF camera are typically soft wide open....
It really is a nice lens for the price. One thing to watch out for is that focus accuracy is not as good as the USM Canon's. The lens is sharp if you focus correctly, but you'll wind up with more OOF shots with this lens than others. The solution is to pay attention to what you're taking photos of - when the camera says the subject is in focus, check with your eye to confirm it's in focus. If not, focus again until it's in focus. You can get around this a bit by using AI Servo which will generally give you more accurate focusing with all lenses, assuming your subject can be framed correctly using it.
The best I can gather is that sometimes One Shot (on the non-1 Series bodies, at least) mode will stop focusing when it's "good enough", while AI Servo will continously re-focus to get the most accurate focus distance. You can try this easily with a focus chart. Take 5 photos of the focus chart in One Shot (forcing the lens OOF between shots) - they'll all have differing amounts of front/back focus. Then take 5 photos in AI Servo and the variation will be much smaller, if present at all.
Glad your happy with it. If you ever get the chance you should try the Sigma 24 f/1.8, it is actually a little bit sharper! (very close focusing lens also)
Still can not believe how fast the lens got to you...
