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Re: [OM] 21mm f3.5 SC or MC - SC FS

Subject: Re: [OM] 21mm f3.5 SC or MC - SC FS
From: dreammoose <dreammoose@xxxxxxxxx>
Date: Sat, 06 Jul 2002 18:37:40 -0700
I think you are reading more information than is there into Gary's tests. He says that comparisons between lenses are only valid at the whole letter grade level except in the instances where he did paired comparisons. He has also said his ratings for vignetting are subjective. I suspect that is also true for distortion.

Also look at the 2 tests of 21/2.8 SCs, one shows "slight pincushion (none?) and the other " slight waveforming with slight barrel" . Then look at the 2 24/2 MCs, "pronounced waveform" and " moderate waveforming with strong barrel tendency ". It doesn't matter how much of this variability is in the tests and how much in sample variation, there just isn't enough info here to conclude that the SC versions are generally better or worse in distortion than the MC versions.

C.H. Ling stated :

"Yes, in my experience the 24/2.8 SC is sharper than the MC, the 28/3.5
is also sharper than the 28/2.8. My S/N 5xx,xxx SC 50/1.4 is as sharp
as my S/N >1,100,000 but the 50/1.4 SC with S/N 3xx,xxx was very poor
at f1.4 when compared to the others."

I have no doubt that is true of the samples he had as C.H. is a careful tester. On the other hand, look at the resolution in Gary's tests of 2 24/2.8 MCs and the 1 SC that was tested with aperture/mirror prefire. By Gary's stated standards, these all are identically sharp, as the differences are almost all 1/3 grade. Then look at the SC on an OM-1 to see how much of the resolution and contrast depends on parts of the system other than the lens alone. (Of course, if it is only the lens, some SCs are apparently much worse than MCs?)
Then C.H. says:

"Believe it or not, some SC lenses seems to have higher contrast then
the MC, like the lens I mentioned above. But backlight performance is
another issue, the SC are usually poorer. "

Oops, there are even more things to worry about!

Moose

plp@xxxxxxxx wrote:

Gary's lens tests only include a SC 21mm f3.5, but the
Unofficial Olympus OM Zuiko Lens Page suggests that a MC
version of this lens is the current one.  Also, it seems
to be a trend that the cheaper wide angle lenses were
better in the SC versions.  The 24mm f2.8 comes to mind.
Has anyone compared the SC & MC versions of the 21mm f3.5
(if the MC version exists, of course)?  With the 24mm f2.8,
the distortion became worse in the MC version.  I am very
curious if the waveforming and/or barrel distortion became
worse in the MC 21mm f3.5.



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