Hi Mary
I have owned this lens for about 10 years and it is my weapon of choice for product photography work. It is built like a tank with very low distortion and is sharp.
It is slightly wider than the 28mm and 2/3 of stop faster
I took my son's wedding photos with this lens on a 40D
example here
http://www.worldphotographyforum.com...hp?photo=41847