I assume that you are talking about the autofocus glass and not the FD mount glass of yesteryear (which is really good glass as well) Stay away from any and all consumer glass if you are serious about what you do with the exception of the 35mm-70mm 3.5-4 zoom with a metal mount. Although slow, this lens actually makes very nice photos. I have one for travelling.
There is a comment below about the 16/17-35mm lenses not being very sharp. I have to agree, BUT if you can find a pre-USM 20-35 2.8 L then jump all over it. It is better than any wide angle zoom made by any company and is what I still use with my canons. It is smaller and heavier than the 17-35 and although it is a little noisy focuses fine.
The problem is finding one. On the used market they almost always sell quickly and for more money than the newer (but used) USM 16/17 lenses.
Seeya,
Shane Bevel
Staff Photojournalist
The Times
