Those of you who've read my posts know that I absoluetly love my 17-55 f/2.8 IS. It's probably the best all-around general purpose lens with superb image quality (that is, on a 1.6x body). However, I'm unsure that the 17-55 will be a cure-all for Sheiky. The reason is simple--the 17-55, in my opinion, hunts for focus a little to often in low-light situations. I've run into this problem on several occasions where I simply couldn't obtain focus even though I thought there was enough ambient light to do so.


Therefore, in this situation, with the poster's specific needs in mind, I'd be inclined to suggest the two-lens setup. However, my best advice is to save up a little extra money and rent the 17-55 first. If it focuses well enough in low light situations for your needs, then buy it--it's a more useful lens than the 17-40. However, if you find that it doesn't focus well enough in low-light situations, thenrent the 50 f/1.4 and see if it will perform up to your standards under those same conditions. If so, then buy the 17-40 and 50mm combo.