Quote Originally Posted by darinwc View Post
Shawn: wow, I did not know there was usch a diffrence. I will definately look into that. THX
You're welcome. =)

Here is a great resource for modern lenses:
http://www.ebonycamera.com/articles/lenses.html

Scroll down the chart under glossary of terms.

"The flange focal distance of a lens is the distance from the rear surface of the lens shutter (i.e. the front surface of the lensboard) to the focal plane (i.e. the film plane) when the lens is focused at infinity."