In article <5huach$cbd@mcrware.microware.com>, tada@microware.com says...
>In <3342C82A.7419@dontspamme.org> duane
>[somebody asks if a 50mm 1.2 is "no good" wide open]
>[dg@dontspamme.org answers that a 50mm 1.8 beats both if you don't need the
> extra light, but when you need the light you don't have a lot of
> choice.]
>
> Maybe a better question here is which lense is better at f1.4? I tend to
>shoot a lot of available light and find that I have to use the max aperatures
>frequently to get reasonable shutter speeds. Since most lenses perform best
>at middle aperatures, and since 1.4 is closer to "middle" on a 1.2 than 1.4...
>
> Does anybody know the answer? I've considered trading my 1.4 in on a 1.2
>and getting a 1.8 for when I have my tripod handy. Don't really need two
>50s but the 1.8 lenses are cheap around here.
>
> Probably just save for the 20mm I've had my eye on though...
OK.... Here it is... Again... :-)
The current Nikkor 50's are very similar in performance from about f4
through smaller stops (the exceptions: the f1.8 has no linear distortion;
the f1.4 and f1.2 have a small amount of barrel distortion; and the f1.2
at infinity is a tad softer in the corners). At wider stops, their
performance characteristics diverge somewhat (assuming good samples of
each type). The f1.8 is the most uniform in sharpness to the corners at
f2 at all focus distances, but the others are infinitely better at
f1.4...;-). The f1.4 has slightly better contrast over most of the frame
at f2 than the f1.8, but is inferior at the far edges and corners.
Close-up performance is inferior to the f1.8 at wide apertures. At f1.4,
the f1.4 contrast is noticeably reduced. The f1.2 is notably poor on
the edges at wide apertures at infinity focus, and is also not wonderful
at minimum focus at wide apertures, but it is really excellent wide-open
at 4-15 feet or so (faster lenses often show more distance sensitivity).
Bottom line: where linear distortion, sharpness uniformity, and good
close-focus performance are important, choose the f1.8; where best
performance at f2 over most of the frame at a wide range of distances
is important, choose the f1.4; when the best possible performance at
f1.4 is important, and the distance setting is generally around 4-15',
choose the f1.2.
Hope This Helps