[rollei_list] Re: OT - Bokken (was: Question on operatingand on screen for Rollei GX and Hood)
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 25 May 2005 16:24:41 -0700
----- Original Message -----
From: "Marvin Wallace" <Marvin0@xxxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, May 25, 2005 3:55 PM
Subject: [rollei_list] Re: OT - Bokken (was: Question on
operatingand on screen for Rollei GX and Hood)
> It is good to know that all Rollei Planars are the same;
> the question
> regarding Summicrons vs. Planars is asked in the light
> that both produce
> wonderfully detailed black and white negatives with
> information across the
> whole negative; including micro details and good shadow
> and highlight
> information.
> I am not a camera collector I am a photographer and like
> to use the zone
> system, I would like to ask your opinion on what the best
> standard lens on
> any format any one has used, in order to not get pedantic
> keep in mind that
> this is a Question of opinion, The 3.5 F I owned was
> stunningly sharp yet
> exquisitely detailed with a soft tonal range.
> Marvin.
>
The Zeiss Planar used on f/3.5 Rolleiflexes is a generic
six element lens known variously as an Opic or Biotar. The
prototype is the original (1896) Zeiss Planar of Paul
Rudolph. This design was further developed by Horace W. Lee,
of Taylor, Taylor, and Hobson (England) who made use of some
assymetry (the two halves have somewhat different power) in
order to help correct some residual aberrations and raise
the speed from f/4.5 to f/2. Lee's lens was called the Opic
(1924)but was not marketed well by TT&H so the design did
not become well known. It was again taken up abut a year
later by several designers including Tronnier of Schneider
in a lens designed, evidently for Leitz, called the Xenon,
and by Willie Merte of Zeiss for the very well known Biotar.
This is an extremely poweful design. It is the basis for
nearly all lenses of f/2 or faster for 35mm still cameras
and for motion picture cameras.
The first Leitz design using the Opic/Biotar was the Xenon
but that was followed in 1933 by the Summar designed by Max
Barek. The Leitz Summicron is not a single design but
several variations of the Opic with various arrangements of
additional elements, both cemented and air spaced. Mostly,
the approach seems to have been air spacing the cemented
component in the rear cell, but there are variations. The
reason for air spacing is that it gives the designer more
degrees of freedom to correct certain residual aberrations.
Cemented surfaces were popular before good lens coatings
became available because they have low reflection and thus
do not contribute significantly to flare. However, they do
limit the designer's options
The five element Xenotar-Planar type is actually another
variation of the original Planar. In it the positive element
in one side is elminated by separating the cemented pair and
making the negative one a thick, deeply bent meniscus. The
resulting lens still retains much of the advantages of
symmetry but results in a simpler structure. The five
element version is attributed (by Kingslake) to Charles G.
Wynne of Wray Optical (England) c.1944. The Zeiss and
Schneider versions of this lens are somewhat different in
arrangement but generally similar in performance. Five
element lenses were used in the f/2.8 Rollei cameras. The
design was changed to a conventional six element design for
the f/3.5 camera presumably because it proved to be less
expensive to make despite the additional element and
cemented surface.
In any case, all of these lenses, five element and six
element Planar/Xenotar, and the Leitz Summicron, are all
memebers of the same family of lenses.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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