how many sigma lenses have you owned and how many had to be sent it for calibration or rechipping. also, what was the outcome on the 18-50...were you happy with it when it returned from sigma and do you still own it?
let's just say "a lot." as for sending in, several had to go in for FF issues, one had to go in for incorrect EXIF data. by and far most were good to go. as for the 1850, they did correct the focus issue but as i posted at my site (only recently removed), i sold it only bc i wanted the range of the 1785. optically both the 2470 and 1850 are better than the 1785. but i'm pleased with the canon zoom as a walk around.

