[rollei_list] Re: 2.8A Jena Tessar question
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Fri, 14 Jan 2011 11:00:54 -0800
----- Original Message -----
From: "Dan Daniel" <dan.daniel.photos@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Friday, January 14, 2011 10:18 AM
Subject: [rollei_list] 2.8A Jena Tessar question
I was recently given a non-functioning 2.8 Tessar
Rolleiflex. In breaking it down for cleaning, I noticed
that the barrels of the taking lens set are stamped with
serial numbers. The numbers match for the front and back
set.
Would this have been done by F&H after coating? Or does it
indicate in any way that the issue of de-coupled pairings
that I have heard about didn't happen with this set?
Thanks for any info. I haven't been able to take any
photos with the camera because of problems with the film
transport so I can't say anything about the quality of the
lens itself.
I have seen threads asking for info on these models, so
here it is:
Body: 1101075
Viewing: Nr. 819302 Heidoscop-Anastigmat 1:2.8 f=8cm
Taking: Nr. 2448307 Carl Zeiss Jena Tessar 1:2.8
f=8cm T[in red]
The barrels of the taking lenses are stamped 448307; there
is no '2' at the beginning.
There is a hand=written note on the barrel of the viewing
lens: F=79.4 No other markings on viewing lens barrel.
Dan Daniel
San Francisco, CA
The serial numbers on the cells were put there by Zeiss
not Rollei. If the story about the mis-matched components is
true they were mis-matched before being mounted so the
serial number match is of no significance. In a Tessar most
of the power is in the back combination and most of the
correction is in the front group. However, I've recently
found that one can interchange cells without a lot of effect
on the image although there is a change in focal length. I
am not sure what aberrations became objectionable in the
Rollei f/2.8 lenses, knowing that would give an indication
of what went wrong. Note that at f/2.8 a Tessar is working
right at the limit of the design capability. Tessars tend to
have something called oblique spherical aberration
inherently. This looks something like coma in that it
produces smeared imags of points as one moves away from the
optical axis. Its stop related so it gets better as the lens
is stopped down. In an f/3.5 lens its gone by f/8 but causes
a noticable loss of sharpness at the corners and edges when
the lens is used wide open. The f/2.8 lens would have had
even more and probably would not have been sharp wide open
even if made correctly. There are some fairly good f/2.8
Tessars but none of them can match the performance of more
complex lenses at higher speeds.
I also understand that Rollei may have exchanged lenses
in cameras with really bad ones so if your lens is a good
one (and some were) that may be the reason.
This whole episode is an indication that QC was not very
good at either Zeiss or Rollei at the time.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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