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Lens Cell Cleaning



 
 
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  #31  
Old February 19th 11, 12:43 AM posted to rec.photo.equipment.large-format
Nicholas O. Lindan
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Posts: 1,227
Default Lens Cell Cleaning

"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


  #34  
Old February 21st 11, 06:06 AM posted to rec.photo.equipment.large-format
Richard Knoppow
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Posts: 751
Default Lens Cell Cleaning


"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



  #35  
Old February 21st 11, 08:55 PM posted to rec.photo.equipment.large-format
Nicholas O. Lindan
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Posts: 1,227
Default Lens Cell Cleaning

"Richard Knoppow" wrote
I have a prototype Angulon, its awful.


The two good samples I have had were both 'Linhoff' branded on the shutter
and were late production.

--
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


  #36  
Old February 22nd 11, 12:05 AM posted to rec.photo.equipment.large-format
[email protected]
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Posts: 428
Default Lens Cell Cleaning

On 2/21/2011 3:55 PM, Nicholas O. Lindan wrote:
"Richard wrote
I have a prototype Angulon, its awful.


The two good samples I have had were both 'Linhoff' branded on the shutter
and were late production.



The 135mm xenar I had was in a linhoff shutter too. It was abysmal..


Stephey
  #37  
Old February 22nd 11, 04:47 PM posted to rec.photo.equipment.large-format
Thor Lancelot Simon
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Posts: 163
Default Lens Cell Cleaning

In article ,
Nicholas O. Lindan wrote:
"Richard Knoppow" wrote
I have a prototype Angulon, its awful.


The two good samples I have had were both 'Linhoff' branded on the shutter
and were late production.


Interesting. I had a 90mm Angulon which I would characterize as just
barely acceptable -- but not truly awful like the contemporaneous 120mm
Angulon I tried around the same time. Mine too said "Linhof" on the
shutter.

I know at some point Linhof started doing very stringent re-QA on
every lens they sold. Supposedly they duplicated the entire QA
setup that Rodenstock used at the end of their production line, and
supposedly they did actually reject some lenses that had passed
manufacturer QA (though it is not clear whether this means the
manufacturer had actually tested the lenses that failed, or just a
statistically significant sample of lenses from the same run). I
wonder if this was because of spotty quality from one or more suppliers
earlier on.

--
Thor Lancelot Simon

"We cannot usually in social life pursue a single value or a single moral
aim, untroubled by the need to compromise with others." - H.L.A. Hart
  #38  
Old February 22nd 11, 07:06 PM posted to rec.photo.equipment.large-format
[email protected]
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Posts: 428
Default Lens Cell Cleaning

On 2/22/2011 11:47 AM, Thor Lancelot Simon wrote:
In [email protected] .com,
Nicholas O. wrote:
"Richard wrote
I have a prototype Angulon, its awful.


The two good samples I have had were both 'Linhoff' branded on the shutter
and were late production.


Interesting. I had a 90mm Angulon which I would characterize as just
barely acceptable -- but not truly awful like the contemporaneous 120mm
Angulon I tried around the same time. Mine too said "Linhof" on the
shutter.

I know at some point Linhof started doing very stringent re-QA on
every lens they sold. Supposedly they duplicated the entire QA
setup that Rodenstock used at the end of their production line, and
supposedly they did actually reject some lenses that had passed
manufacturer QA (though it is not clear whether this means the
manufacturer had actually tested the lenses that failed, or just a
statistically significant sample of lenses from the same run). I
wonder if this was because of spotty quality from one or more suppliers
earlier on.



I have heard this same thing but question this given the 135mm xenar I
had, that was horrid, was in a linhof shutter. Obviously some other lens
other than the original one could have been put in this shutter by
someone along the way to make it appear to be a better lens than it was.
I suppose seeing the linhof brand on a shutter could help "prove" it's a
good sample but given the age and unknown history, it's not a fact cut
in stone anymore.

Stephey
  #39  
Old February 22nd 11, 09:09 PM posted to rec.photo.equipment.large-format
Thor Lancelot Simon
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Posts: 163
Default Lens Cell Cleaning

In article ,
wrote:

I suppose seeing the linhof brand on a shutter could help "prove" it's a
good sample but given the age and unknown history, it's not a fact cut
in stone anymore.


Right. At one point in the mid-90s, the Linhof factory rep for the
U.S. used to very loudly hold forth here about the special Rodenstock
testing machine Linhof had acquired for this purpose, etc. etc. -- but
then again, he was also the Rodenstock factory rep.

He didn't typically respond to questions about what might be wrong with
Rodenstock's own quality control such that Linhof felt they needed to
repeat it! (Of course, this was a little unfair, since Linhof did not
relabel *only* Rodenstock lenses... but it was fun to yank the guy's
chain.)

I suspect Linhof was badly burned by questionable lenses at some point
and decided on this testing program to reduce warranty costs or brand
image problems. That would imply that after some point, Linhof-marked
lenses were particularly good, while before that time, they may well
have been particularly bad.

Since for Linhof's main competitor, there were always both budget
(Wollensak) and premium (Kodak) lenses available, someone having an
awful experience with a Raptar was not likely to abandon the Graphic
or Graflex cameras entirely. But if Linhof was getting all or most
of their lenses from Schneider at some point and Schneider was churning
out Xenars of poor quality -- which seems to have been the case! -- then
they would need some way to escape the damage this could do their brand.

--
Thor Lancelot Simon


"We cannot usually in social life pursue a single value or a single moral
aim, untroubled by the need to compromise with others." - H.L.A. Hart
  #40  
Old February 23rd 11, 03:14 AM posted to rec.photo.equipment.large-format
Richard Knoppow
external usenet poster
 
Posts: 751
Default Lens Cell Cleaning


"Thor Lancelot Simon" wrote in message
...
In article ,
wrote:

I suppose seeing the linhof brand on a shutter could help
"prove" it's a
good sample but given the age and unknown history, it's
not a fact cut
in stone anymore.


Right. At one point in the mid-90s, the Linhof factory
rep for the
U.S. used to very loudly hold forth here about the special
Rodenstock
testing machine Linhof had acquired for this purpose, etc.
etc. -- but
then again, he was also the Rodenstock factory rep.

He didn't typically respond to questions about what might
be wrong with
Rodenstock's own quality control such that Linhof felt
they needed to
repeat it! (Of course, this was a little unfair, since
Linhof did not
relabel *only* Rodenstock lenses... but it was fun to yank
the guy's
chain.)

I suspect Linhof was badly burned by questionable lenses
at some point
and decided on this testing program to reduce warranty
costs or brand
image problems. That would imply that after some point,
Linhof-marked
lenses were particularly good, while before that time,
they may well
have been particularly bad.

Since for Linhof's main competitor, there were always both
budget
(Wollensak) and premium (Kodak) lenses available, someone
having an
awful experience with a Raptar was not likely to abandon
the Graphic
or Graflex cameras entirely. But if Linhof was getting
all or most
of their lenses from Schneider at some point and Schneider
was churning
out Xenars of poor quality -- which seems to have been the
case! -- then
they would need some way to escape the damage this could
do their brand.

--
Thor Lancelot Simon


The curious thing is that Wollensak's prices were no
lower than Kodak's for their "premium" lenses. I think there
was some sort of design blunder made on the design for the
Raptar/Optar lenses used on press cameras and the Enlarging
Raptar lenses, which are also pretty bad. Kodak's Ektar
lenses are uniformly excellent as are the Enlarging Ektars.
Even Ilex lenses, also not cheap by any means were head and
shoulders better than Wollensak. Now, another curiosity is
that the Optar lenses made by Wollensak for the Series-D
Graflex are excellent. A different design even though still
a Tessar. They were offered as an alternative to the Ektar
lenses for these cameras but the price was about the same.
I think Wollensak got the reputation for being cheap
because they made a lot of OEM lenses for cheap cameras. So
did Ilex for that matter.
Wollensak shutters OTOH are excellent and, since they
use all hair-springs, can be rebuilt with new parts.


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



 




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