I recently had a chance to check out a Leitz Rangefinder
Double Aspheric Horribly Expensive ($3800 when new) 35mm f1.4
lens, courtesy of Nick Silva (who kindly shot the tests to order
and supplied the film to me). I shot similar test film (B & W and
color) using a Nikkor 35mm f1.4 to attempt a comparison. Though the
Leitz lens remained in California and my 35mm f1.4 Nikkor remained
in New York, I have reasonable confidence that the results of this
long-distance comparison are reasonably valid. So, here is what I
found:
-- At f1.4 and infinity, the sharpness of the center and corners
are similar in the two lenses, but the Leitz is better at the edges
and a bit worse 1/2 out from the center to the corners than the Nikkor
(the Leitz is somewhat sharper in most parts of the frame at f1.4).
-- At f2, the Leitz is uniformly and noticeably better than the Nikkor.
-- At f2.8, the two lenses are closer in performance, with the Leitz
somewhat better, especially at the edges and corners.
-- At f4, the two lenses are close in performance, with the Leitz
slightly better.
-- At f5.6, they are nearly identical, with the extreme corners
of the Leitz slightly better.
-- At f8, they both improve again slightly, and continue to be
virtually identical in performance at infinity focus.
Performance checks at about 5' with the two lenses were more difficult
to compare, but they indicated that the results were reasonably similar
to those at infinity. F5.6 is required with both lenses to clean up the
far corners. Illumination is more even at wider apertures with the
Leitz, and exposure from stop to stop going toward wide-open is more
uniform with the Leitz than with the Nikkor. The Leitz lens shows
some asymmetry in its performance indicating a slight optical
misalignment in the checked sample. The Leitz double aspheric
35mm f1.4 rangefinder lens is a very fine performer, and somewhat
better than the 35mm f1.4 Nikkor at the widest stops - but it
achieves this at a VERY much higher price! (And for the fun of it,
and to put all this in perspective, I added a recent version Nikkor
35mm f2.8 PC, and a MF Nikkor 35-105mm f3.5-4.5 [selected sample]
to the mix. Briefly, the PC showed about equal center performance
and better corner performance than the Leitz at f2.8 and infinity.
At f5.6, the Leitz showed slightly better center performance, though
the Nikkor PC had better corners. The 35-105mm Nikkor at 35mm and
infinity had better corner performance than the f1.4's throughout,
though the rest of the frame lagged slightly behind.)
Hope This Helps