It occurred to me that I have barely spoken about one of the biggest purchases I've made, even though I used it in the Trigun photoshoot, namely the Sigma 17-50mm F2.8 EX DC OS HSM.
First impression was that it was large. I had only used the plastic 18-55 before, and the difference in size and weight was substantial. It felt like a serious piece of gear. Of course I also looked at Canon's equivalent offering, the 17-55 f/2.8, but decided to pass on it because of price and size. For the money saved I could buy other gear (which I eventually ended up doing), and I was also more attracted to the shorter and thicker size of the Sigma.
Initial tests were good, and I was very satisfied with the image quality I got from the photoshoot, but I did notice a couple of issues, mostly dealing with low-light auto-focus (the trouble of most cameras) and wide-angle focus. Using it on the 1000D I would often find I'd get better results if I first zoomed in to focus, then zoomed out to wide-angle for the shot. A workaround, but not anything that would fly in the long run. Not really sure if the problem was the lens or the body, I prepared myself mentally to send the lens back.
On my way back from work the other day I decided to stop by the camera-store, since they get in used stuff sometimes that they sell on. Asking what they had, they guy brought out a 40D, same model I had looked at earlier but missed, as someone else got it before me. After some deliberation I went back today and got it.
And I must say the Sigma feels like a completely new lens when mounted on the 40D. On the 1000D it would often hunt for focus, and was just about on par with the 18-55 for speed, but on the 40D it feels a lot faster and more accurate. (Perhaps the Sigma is made with f/2.8 cross-type sensors in mind rather than the slower f/5.6 of the 1000D.)
And beyond the improved AF of the 40D there is also the possibility of exchanging the focus screen to get more accurate manual focus, thereby eliminating the dependance on automatic focus!
Update: just tried the Sigma on a friend's 450D, focus was good. Could it be that it doesn't work well with the 1000D AF sensor?