Originally posted by tybeck I'm interested in a solid answer on these lens as well. So much so I've been thinking of renting them for a test session before I invest further. Nobody would practically need all three lens which is most likely why a "side-by-side" comparison hasn't surfaced. Anybody got any good criteria for testing wide-angle lens? Maybe I should start a seperate thread on this.
you can compare the technical stuff on photozone, i think they've got all of them
the sigma i'm not so sure if they have a review on the pentax mount
thom hogan, a nikon guy, used the 10-20 instead of the 12-24 before he went full-frame even if the 12-24 was superior to the 10-20 in pretty much every way (optics/sharpness, build, af-speed). i asked him why and he said he loves that extra 2mm and when stopped down, the sigma is excellent.
since i used it mostly on landscapes and on a tripod, i stopped it down most of the time. even wide open i liked it for those casual wide-angle fun. love the HSM (don't know if the pentax has HSM), very fast (much faster than my 16-50 SDM), and very quiet.
so do you need the speed, extra 2mm, flexibility of the zoom vs. a prime? i also liked the sigma because it was a lot cheaper than the nikkor and has excellent support/warranty where i'm from.
hope that helps!