::I’m with Dick on this one—I think the reverted change was far less readable, and somewhat off the wall as well as technically incorrect in a few places. I think we should stick with N as the symbol, for the same reasons as Dick; I don’t understand what Glockenlang1 means by “overloaded”. I also think we should stick with vast preponderance of reliable published sources rather than a self-published web page. 

 ::I don’t suggest that the article could not be improved. For example, I’m uncomfortable with the concept of “effective aperture diameter” because the effective f-number derives from an image distance greater than the focal length rather than a change in entrance pupil diameter.