I've been seeing Rodagon "N" enlarging lenses, and most recently, an El Nikkor "N" enlarging lens on EBay.

What does the "N" mean in each case?

As far as Rodenstock is concerned, the letter denotes the enlargement range in which the lens is optimum.

N for the usual range of enlargements from negatives (x2 to x15, according to their pdf). This is probably what you want.

D for close to 1:1 reproduction

See http://en.wikipedia.org/wiki/Rodenstock_GmbH

In the case of the Nikkor lens,some years back Nikon redesigned the lens barrels;more plastic,and an illuminated aperture scale.AFAIK,no changes were made to the optics. So,presumably,the N is for NEW.

Thanks.

Hi !
Well Nikon has _also_ made some change to the lenses : the 75mm f:4 was replaced by a six lenses design 80 mm f:5.6 N if my memory serves me right, these changes appeared at the same N other lenses.