my shiny new Lens just arrived, 15 minutes ago (what a cool looking lens), so took this shot quickly as the light is fading fast, in fact quite dark and overcast (its now raining!) which I think contribued to the noticable noise that you can see in the 100% crop, I would ideally not want to go higher than iso 200 if I can.
canon 400D set to manual, 17-40L at 40mm
RAW (then converted to tiff using adobe camera raw plugin in Photoshop-CS2 on my Mac) no other processing apart from jpeg for this post
anyways here are the images, reduced to 30% and 100% crop
quite pleased with the bokeh at f/4, I was around 18 inches from the bird feeder, in fact I think the DOF is around 2 inches max at this distance at f/4