DekHog initially got me interested in the Sigma 10-20 4-5.6mm UWA earlier this week in one of the other forums here. I located one within 24 hours, and initial results have been very pleasing. NO visible CA in the usual places like foliage or cables or edges of buildings. It's not the sharpest lens I ever had, with less sharpness obvious at the edges of scape type shots. However I bought it for inside use, where it seems fine, and for blurring clouds/water. It also seems pretty good as a general lens for street photography with that wide angle able to give another slant on a take. ( ahem ) Anyway, I have a very colourful bridge near me that attracts me again and again. A bonus of a cloudy sky seemed to be telling me go there again. Canon 60D Sigma 10-20mm 4-5.6 EX DC Niks color efex pro was used give this more effect. But, that Sigma gave me a number of all important keepers which was my starting point. TY DekHog for drawing my attention to the "Siggy"