Sandro wrote in message <63muq4$npg$1@news.nettuno.it>...

>Hi. I would like to know some information about Nikkor 20 mm. Some say that
>the old 3.5/20 mm UD prong lens is still the best one, in terms of sharpness
>and colour rendition. Some other say that the best is the new 2.8/20 mm AFD,
>even though it's made of plastic. A friend of mine is always describing me
>how wondrful the 4/20 mm Ai is....
>I would really like to know different opinions, also because it's very
>difficult to find tests on old lenses. If you want to, please answer to
>gas5498@iperbole.bologna.it


If you really want to hear it from the horse's mouth (I will entertain opinions
regarding whether or not this is from other parts of the horse...;-), this is
what I found from trying at least a couple of each of these Nikkors:
- 20mm f3.5 UD (72mm filter), nice image quality if well stopped down
(f11-16) to bring in the edges
- 20mm f4, not very good at the edges, but OK if well stopped down
- 20mm f3.5 (52mm filter), better evenness of performance across the
frame than the f4, but never wonderful even at small stops
- 20mm f2.8 (MF versions - I hate plastic-barreled lenses [optics are the
same on those, though...;-]), useable at f2.8 if you don't mind poor edges,
but it is VERY fine by f5.6 everywhere (given its excellent performance
by f5.6 and its compact size and light weight, this is the best, though the
large-version [used] can be an excellent less expensive substitute)
For quite a while I dispaired of ever liking a Nikkor 20mm retrofocus. (When
the original 20mm UD came out, I tried it, and immediately bought the older
non-retro 21mm f4 - it was a better lens in some ways, though it had some
serious optical problems also.) This FL had so many weak entries for SO
long! But Nikon more than caught up when they introduced the really
excellent f2.8 version, which is among the best Nikkors
(which is saying something! ;-).
Hope This Helps
David Ruether - http://www.fcinet.com/ruether