So where do we find the "highest evolution" of the Tessar lens? Late Contaflex
(Super BC / S), late Rollei 35 Tessar (Singapore) and last version of
Rolleiflex T?
Jan
On Jun 6, 2020, at 9:56 PM, `Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
I have a much earlier edition of this book. I need to find this edition
but its a bit expensive new so I will see if I can find a used one.
Kingslake meant this as an introductory book on photographic optics rather
than a text book. He is usually very clear in his explanations.
A note: Cemented elements are frequently used by lens designers to
simulate a type of glass not available. Kingslake's remark about being able
to duplicate the performance of a Tessar with a high index glass in a triplet
is very interesting. I was told by a lens designer friend that computer
design programs could not improve the old Tessar designs much and that high
index glass did not improve them a lot. I have a program with the old
notebooks (lost a name again) from Zeiss. They experimented with aspherical
surfaces in the Tessar. The problem is that aspherical surfaces had to be
individually hand figured so were not suitable for mass production. Computer
controlled machinery has changed that. I was also told or read that the
original Tessar could not be built any more because the type of glass it
called for were no longer made.
Kingslake's remarks about the Dialyte are also interesting. This is the
basic type of the Goerz Dogmar and Apochromatic Artar. It was also used by
Kodak for several lenses including the old 70 series. The only one of those
that survived was the 201mm, f/7.7 Kodak Anastigmat which was renamed an
Ektar when coated. These lenses can have nearly perfect correction for
chromatic aberration, both longitudinal and lateral and chromatic difference
of magnification so were widely used for process, enlarging and copying
lenses. This is why the Apo Artar, designed for close to 1:1 magnification
works well at infinity focus.
Anything Kingslake wrote is worth reading.
