This test is on an older Sigma 90mm f2.8 macro lens which, although very much designed as a film camera lens, performs extremely well on both my Nikon and Fuji S2 bodies. In fact this is one of the sharpest lenses I’ve used with digital - with portraits the Sigma 90mm macro is maybe even a wee bit too sharp at times. Not every person benefits from that amount of sharp detail.
It’s only real drawback is a considerably cooler color rendition than my Nikon lenses but with digital that’s not exactly a huge problem. Build quality is excellent, with only the smooth and narrow manual focus ring to complain about. Although classed as a macro lens it doesn’t actually focus down to 1:1 with film, but with digital SLR cameras the focal length multiplier takes you most of the way there. I bought this lens on ebay and it didn’t come with Sigma’s usual lens hood, but as the front element is well recessed that hasn’t been a problem.
Overall this is an excellent lens, and feels so well made that the main concern, if you get hold of one, is with compatibility - especially with Canon DSLR’s - check that it does function correctly with your camera before you buy. I’ve found that older Sigma lenses are usually OK with Nikon or Sony /Minolta, but not always with Canon.
The Sigma 90mm f2.8 AF Macro is a really good lens, well worth a search on ebay for one of these or the 50mm version.