Except for letting light in in indoor situations, I do not see the 4.5 aperture to be a big problem. Most journalists use wide angle lenses at a high depth of field, so stopping down the lens would be needed anyway.
The sigma 15-30 is heavy, bulky, washed out color, real tight to zoom..I returned it and got the 17-40. The 17-40 is my favorite lens. its smooth, light, tack sharp.nice saturated color. I have to stay around 20 mm if I use the onboard flash on the 20D, or the lens will get in the way of the flash
I bought my 17-40 L this past Sat. I am stunned at just how good this lens is. You will not be disappointed. It's awesome! Tack sharp, fast focus, and bright. There's now way I would by a different lens just for a little wider perspective. BTW, I am using it on a 10D.
I've got the 17-40L, and have heard great things about the 15-30 Sigma. The 17-40 is plenty wide on my 10D and 20D for most everything I do. Of course, it is *much* better on a 1D with only the 1.3x crop.
Have you thought about the 15mm fish from Sigma? That was also a great lens for my 10D.
Well I *was* leaning toward the 17-40, until I got some of my photos critqued in class today and several of them were commented on as 'not having used a wide enough lens' - and I was using my 18mm!! Sooooo looks like I'm back to the 10-22mm now, but I wish they would say when it is going to be available. 1.6x crop is not good sometimes...
Also, now I'm back wondering if I should get the used 10d or the new 20d. With the 20d I would be able to use the Canon on both cameras, with the 10d only on my Rebel. Also, I'm scared of buying a used camera that has some minor problem that I would not be able to detect immediately because I'm still relatively new to all this. Grrr. hopefully someday someone will pay me for doing this, more than the other way around...
