Since I have a film camera that I use aswell, and the 10-12mm range although awesome to have, Is replaceable With the Full frame 12-15mm The lens would give me on my N80. So do you think it would be a good idea to trade up from the 10-20 to the 12-24? I don't use the lens THAT much, And I bought the 10-20mm new, so it still has a warranty. I haven't heard much about the 12-24 since it is apparently quite heavy, and the Nikon 12-24 is better / brighter. So anyone have experience with the Sigma 12-24? I'm not even sure what they run for used because I rarely see them! Right now my widest Lens for film is a Sigma 24mm f1.8, Which's close focus distance and great sharpness at f1.8 makes it a fantastic lens to have. So I can benefit from the wide end. Thoughts?