If you have the money, it would seem that any of these L zooms could help you out. I wouldn't worry too much about IS unlesss you contemplate walkaround conditions (not landscape right?).
Wide and Fast: 16-35 f/2.8 L
Wide and Value: 17-40 f/4 L *
Almost wide and fast: 24-70 f/2.8 L
Almost wide and versatile: 24-105 f/4 IS L **
* I'd get this if I was low on cash - great lens for the money.
** Just released
Bear in mind, with the 20D, none of these choices are super (dramatically) wide, but they cover the bread and butter focal length ranges. For really wide coverage, you would be looking at the dedicated EF-S 10-22. Not an L lens, but I get great results with it. You will still need another lens to fill in the gap between 22mm and 70mm though.
Thanks Bob. I really do need another lens. Working with a minimum of 112MM effective using my 70-200 is getting unuseable in lots of situations. Yes, that 24-70 f/2.8 L Iwas thinking about too. But I was thinking about a smaller lens, like the 16-35 f/2.8 L. I know there would be a gap, but the 16-35 x1.6 becomes a 25-56, which seems like a really nice range. Then, x1.6, I'd only have a gap between 56-112, or 56mm gap. Sometimes, I cannot walk back far enough for the 112. I'm trying to kill two birds here. If I get the 16 to 35 I have landscape fairly well covered, and could use it for smaller areas too.
On the other hand, the 28-70 becomes a 45-112, and 112 is too darn big for lots of stuff, and I already have 112 on my 70-200 effectively. I also want to avoid a slower lens because I want the shallow DoF when I need it.
So is my reasoning sound here? If so, goodie. Now I get to drop another 1400.00 and yet ANOTHER heart attack.
