PBase

I recently purchased a Canon 40D with a 24-105mm 1:4L IS USM LENS. I would also like an Ultra-wide zoom. The salesman recommended the EF 17-40mm f/4L USM.

The 24-105 appears to overlap about 70% of 17-40mm range.
AmI missing something here?

You're going to pay a lot to get that extra 7mm at the wide end when a few steps backwards will do it for you

Essentially, what range do you want? Would something in the 12-24 range give you better scope and be a better use of your money, or you could consider the other end and go for a 70-200 F2.8?

"You're going to pay a lot to get that extra 7mm at the wide end when a few steps backwards will do it for you."
Good point.

"Essentially, what range do you want?"
I was considering the 10-22mm lens.

I think I'll postpone any lens purchases until I'm more familiar with the camera.