Liz,
I shot a couple of Sheltie Specialties over the weekend and wanted to share both the formals and the portrait session where I used the 28-135 IS.
For the formal, I used a single Alien Bee 400 slightly forward of the dog and 10 feet away bounced off of a silver umbrella and shot manual exposure at F8 and 1/200 sec. Shot RAW, processed for basic exposure and pre-sharpened only in Photokit Sharpener.
The portrait was taken outside, in open shade, at Aperture Priority at F5.6 to diffuse the background. Again, original in RAW, adjusted for brightness only, pre-sharpened in Photokit Sharpener.
I'm satisfied with both the sharpness of the lens stopped down and the bokeh opened up. And the color is typical Canon: warm and smooth.
Thought you'd like to see these.
Jim