I just got the 15-85 and so far am really pleased with it. I love that the wide end is 15; doesn't sound like much difference from 17, but is is almost 6 degrees wider angle of view. (FYI Bryan's lens spec page shows the angle of view for most lenses.)


I had the same decision between the 15-85 and the 17-55. I liked the wider appeture of the 17-55, but the larger focal range of the 15-85, especially at the wide end. I understand the IQ for both lenses is similar, but I don't have the 17-55 to compare.


I paired my 15-85 with the 70-200IS and this is a fantastic combination: very versitile. I also have the 100 2.8 macro (non-usm) and love this lens: a lot of interesting pictures can be taken with macros.


IMO if you are deciding between these two lenses, I guess your decision basically comes down to whether you want the faster 2.8 appeture or the larger focal length of the 15-85. This depends largly on the type of shooting you do. With your current lenses, do you find that you are always shooting at the extreme focal lengths and wishing for "just a little bit more"? Or do you find yourself wishing for a wider appeture so you can shoot handheld in lower light? Answering these questions will help you determine which of these is better for YOU.


Stephen