for those that might be interested in acquiring this lens for the *istD, i tested a regular 82mm and a B+W Slim 82mm filter threaded to the lens cover with the cap removed. the ordinary filter vignettes slightly wide open and very noticeably at f22. the Slim filter doesn't vignette that i can tell at f22. all this is at the 15mm end, of course. for those of us that like wide angles, the 23mm equivalent FOV of the lens is an adequate replacement for a 24mm lens on a film camera, and is sharp within the FOV that the *istD delivers. it's pretty mediocre at the far edges when on a film camera body though. so, although i am looking forward to trying the Sigma 12-24, i think i can manage with the 15-30 for the time being for my landscape work. i use a circular polarizing filter a lot and being able to attach one without vignetting really matters. if, as i suspect, i can use the same filter on the 12-24, so much the better. if it turns out that i decide to get the 12-24, my 15-30 will go up for sale.
Herb...
