Simon, glad to see another of the converted to DSLR's.

Sigma make extremely good lenses and in some cases they do actually make as good or better than the own brand equivalent. 50mm Prime 1.4 to name just one. As a rule of thumb though, major brands are that bit better.

I took my pictures at the ring last year with a Sigma 70 - 200 1: 2.8 APO DG. Take a look at the pictures that took and I'm sure you'll see that it is a more than capable bit of glass. These retail at around £660.00. Now, I have recently upgraded this lens focal range by purchasing a Nikon lens which was a few sheckles more than I wanted to pay but pushed myself a bit. So, my Sigma is going begging. It is 2 years old and in very good condition. I am looking about £350.00 for it.

Have a look at the pics in the ring thread, if you like what you see and want to give it a try, just ask.