It’s remarkable that you can use the lens at all, George. Tamron says that the 17-50 is for the “exclusive use” with 1.5/1.6 cropped cameras, not full frame. Maybe that simple fact would convince your employer to change?
See: http://www.tamron.com/lenses/prod/1750_diII_a016.asp
Having said that, I like the lens on my 40D. It’s light, small, inexpensive, sharp, great focal range – with none of the problems that plague the images from your full frame camera.
Then again, you could keep the lens and make lots of images with halos and vignetting. It might just win you a World Press Photo award. [rimshot]