[rollei_list] Re: 2.8F opton?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Sun, 6 Jul 2008 20:15:47 -0700
----- Original Message -----
From: "Eric Goldstein" <egoldste@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Sunday, July 06, 2008 6:00 PM
Subject: [rollei_list] Re: 2.8F opton?
Richard -
From the company history we have been told, it would seem
that the
Biometar on the 2.8 B and the Planar on the 2.8 C are very
similar in
their construction...
I'd be curious how the patent data say they differ.
Eric Goldstein
The Planar as shown in diagrams in the Rolleiflex books
is the first one patented by Zeiss. The cemented component
is in the front. I think from the construction that this
must have been a difficult lens to make because of the thin
and deeply curved surfaces especially as they had to be
cemented. The Biometer and Xenotar has the cemented surface
in the second component and the cemented surface is plane.
The Biometar does not resemble this lens except in generic
type. However its closer to the forms mentioned below. Zeiss
did have patents on other forms of the lens with the
cemented component either second or third position. I can
post some data on these if you like. I've just posted the
prescriptions for the Biometar and two forms of Xenotar.
These are all f/2.8 lenses, Schneider has a patent on an
f/3.5 version also.
The limited computer analysis of the three lenses, i.e.
original Planar, Biometar, Xenotar, suggests that the Planar
was very slightly the best of the three with the Xenotar
coming next and the Biometar last, however, the differences
are very small.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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