Well received my 40 in the mail today. Hoping they'll allow me to take it to the concert tonight and see how it works in low light. I would have to say that the focusing is faster than the 35mm f/2 but definitely not as fast as something with a USM or even the Af motor of the 50mm f/1.4. It is pretty quick and almost quiet. If I get anything good for pictures in the next day or two I will post some.