"Bob":http://bobsplanet.com is really a great photographer. By his permission, here's an excerpt on picking lenses. Don't you love IM?

Bob Wise says:
good, how are you?
Rich Tong says:
Goofing off. Scanning 35mm film from 1999 and looking for cameras. Have to leave in 3 minute to go to work We should talk cameras and lenses though, I'm deep into it right now. Think I need the very light Digital Rebel for walking around in China (less obvious, doesn't say rob me) plus the 5D for the serious stuff.
Rich Tong says:
But the issue is what lenses to get? Went though the whole Canon inventory and picked out a few (they are on tongfamily.com), tell me what you think. Also now going through Sigma. The Sigma stuff seems cheaper and if you are smart pretty good.
Bob Wise says:
I love my 24-70L
Bob Wise says:
Going to sell the 17-40 probably
Bob Wise says:
Get the sigma 12-24
Bob Wise says:
only decent wide-angle zoom for FF
Bob Wise says:
I'm definitely a zoom guy instead of a prime guy
Rich Tong says:
So what do you have exactly? I agree, the zooms don't have the same tradeoffs in the old days
Bob Wise says:
I have the 24-70L, 50mm, 100mm macro, 100-400L, and 17-40L
Rich Tong says:
Wow, nice lenses. Here is what I'm thinking: Sigma 12-24, Canon 16-35L, 24-105L, 70-200IS. It is a tossup on the 24-70L vs the 70-105L with the main difference being the F/2.8 vs. F/4.0
Bob Wise says:
24-105L is good. Has IS which is nice
Bob Wise says:
I think you will find that the 16-35 or the 12-24 are redundant
Bob Wise says:
I'm very tempted to get the 16-35 myself
Rich Tong says:
Yup, I was thinking the IS plus the ISO 800 performance of the 5D would help. I agree on the 12-24 vs. the 16-35. One or the other.
Bob Wise says:
the 12-24 seems to have the usual sigma QA issues... a bit hit and miss on getting a good copy
Rich Tong says:
I haven't found a review of the 12-24 yet, but the 16-35L has great reviews and is a good fit for the main lense of the Rebel given its factor. On the Sigma, you get what you pay for I guess, it is way cheaper. Makes ebay look good. these things cost!
Bob Wise says:
I think I'm going to order the sigma and see how it like it. If I don't like it I will sell it and get the 16-35
Bob Wise says:
I have really liked the 2.8 speed on the 24-70, though!
Bob Wise says:
It's a beast of a lens, though.
Rich Tong says:
Yeah, you are right, the 24-70 has the 2.8, but not the IS. These are all very big lenses you are right. been looking at sizes and weights
Bob Wise says:
BTW, the 17-85 IS with the crop works out to be very close to the 24-105 on the FF
Bob Wise says:
I think that is your China rebel lens
Bob Wise says:
I was very torn about getting the 24-105, but had to shoot a low-light wedding and went for the 24-70 - no regrets.
Bob Wise says:
See "my photos":http://www.bobsplanet.com/gallery/main.php?g2_itemId=80
Rich Tong says:
Will check out. Hey, can I edit and blog this whole conversation. You are the font of all knowledge. Oops, got to go! Call me if you've got time, we can BS