panchromatic said:
At my work we have two nikkor enlarging lens for sale. a nikkor 50mm f4 and a 80mm f5.6 (my boss will give me both for 50 bucks) My question is I saw there is a 50mm f2.8 and a f4 is there any quality difference between the two? is it really worth having the f2.8?
Buy both--for $50 you can't possibly go wrong.
Unless you're printing Ilfochromes with very long exposure times, or gigantic enlargements in B&W, you will never need the f2.8 lens. Even when I was printing Ilfochromes, I still used my 2.8 at f4 because it wasn't as sharp at 2.8. The chief advantage of the 2.8 is that it gives you a little brighter image for focusing, but you should focus at the f stop you'll be using anyway. Most enlarging lenses hit their optimum sharpness about two stops down from wide open, i.e. at around f8 or f11 depending. After that, you begin to get diffraction effects, which while not hugely noticeable, do lessen the appearance of sharpness somewhat.
I suspect at f8 or f11, the Nikkor f4 is every bit as good a lens as the f2.8.
Larry