In the well known internet lens tutorial
http://www.photo.net/learn/optics/lensTutorial
In the part about diffraction he uses N to derive his answer. To me it seems that it should be D. However, since I have not seen any indication that anyone has challenged it over the years, I am willing to accept that I may be wrong. But I would like an explaination of why. Can any of you do that for me.
-- graywolf http://graywolfphoto.com
"You might as well accept people as they are, you are not going to be able to change them anyway."
