"Nicholas O. Lindan" wrote in message
m...
"Thor Lancelot Simon" wrote

The Schneider web site says they made the large-format
Xenars until
the mid 1990s (this is a surprise to me). I wonder if
the later ones
were any better.

If the mid 80's sample I had was anything to go by the
later LF Xenars
were every bit as horrible as Schneider's earlier output.

Quality of Angulons was probably worse, but some rather
good
samples did manage to escape the factory.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/da-main.htm
n o lindan at ix dot netcom dot com

I have a prototype Angulon, its awful. It has severe
color fringing, something a lens of this type should not
have at all. My lens designer friend tell me that the
prescription in the patent shows up pretty bad when set up
in a lens optimization program. Later Angulons do not seem
to have this problem so it must have been changed in some
way. The Angulon is similar to a Dagor but uses a different
order of powers in the cells. It also has some power shifted
from being exactly symmetrical to improve its correction for
distant objects. It should be no worse than a W.A.Dagor but
it is. Originally Schneider claimed 105 degree coverage. In
fact, the lens has a circle of illumination that large but
the image quality beyond about 90 degrees is pretty bad. The
Dagor claims 97 degees but also isn't good beyond about 90
even the WA Dagor. Modern WA lenses are much better than
these things but are also much larger and heavier.
My impression is that Schneider was not a quality brand
before 1945 but their lenses after that were very good to
excellent. However, I've checked a couple of f/4.5 or f4.7
Xenars for Speed/Crown Graphics which showed excessive
something, maybe coma or maybe oblique spherical aberration
leading to smearing of highlights away from the center. This
is very similar to the problem with Wollensak Raptar/Optar
lenses for press cameras. Even when stopped down to f/32 the
marginal image is not sharp.


--
--
Richard Knoppow
Los Angeles, CA, USA