Hi there,
Last sunday I was taking pictures of our horse Isis, the results were the worst I've ever seen. Everything was unsharp, all of the pictures were focussed on the fence instead of the horse. Damn!!
Last summer/fall I had to send my Sigma 50-150mm F2.8 back for repair, due backfocus issues. They updated my circuit and reinstalled my firmware, but it seems like all the problems came back.. From like 250 photo's, 5 are well focussed, all the rest are focussed on a fence, or just the background. Sometimes images appear 'sharp' but they still look like they've been taking with a point and shoot camera. It's really terrible. I only and a one-year warranty, so thats a bummer too, since I've had it for 1,5 years now.
I was lucky that I could borrow my friends Canon 100mm F2.8, which is an amazing lense, for a photoshoot last tuesday, or else I would've been screwed..
: o