I have yet to see a good MF f/2.8 Tessar-type. There is a reason Zeiss
and Schneider added a couple more degrees of freedom to get to that
speed.
My super Ikonta 6 x 9 has a front focusing 3.5 coated Tessar... it
does not hold a candle to the 80 f/2.8 Planar on my 2.8C, even at f/8
or f/11
Eric Goldstein
On Wed, Oct 10, 2018 at 3:09 PM `Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
---
I don't have actual knowledge but on the surface it makes no
sense. I would expect that if there were bad lenses it would
have become very widely known quickly as the bad f/2.8 Tessars
became notorious at the time. That was not a design problem but
rather was due to old production having become scrambled during
the war. There were two Planar designs used for the f/3.5
version, a five element and a six element type. My memory is that
the six element version was easier to manufacture. This may be
the source of the rumor. Only the five element design was used
for f/2.8 lenses.
There is a long standing disagreement about whether the
Zeiss Planar or Schneider Xenotar is the better lens, in fact
there seems to be little or no difference.
All of these lenses were intended to provide better
performance at large apertures than the Tessar. Tessar type
lenses have an inherent fault, a sort of coma called oblique
spherical aberration, at large apertures that makes them blurry
in the margins. While many f/3.5 and f/2.8 Tessar type lenses
have been used the basic design is really about an f/6.3 lens.
Nonetheless, Zeiss and others produced some very good Tessar
types up to f/2.8 nonetheless, other designs are better and
faster Tessars were used mainly on lower cost cameras or those
requiring focusing by means of a moving element.
I would sure like to know if there is any truth to this
story but I am very skeptical for many reasons.
On 10/9/2018 7:00 PM, tom rogers wrote:
Myth or fact?
In the 70s, a Zeiss designer attempted to "improve" the Planar
formula and result was a bad batch of Rolleiflex 2.8F lenses
This is from a well-known individual making after market
components for cameras.
The early 50s bad 2.8 Tessar batch is well documented; First I've
heard anything about 2.8 Planars.
Comments?
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
---
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