[pure-silver] Re: Old Kodak Lenses
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 15 Feb 2005 18:31:30 -0800
----- Original Message -----
From: "Gene Johnson" <genej2@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, February 15, 2005 5:32 PM
Subject: [pure-silver] Old Kodak Lenses
> I've been shooting quite a bit with 3 old Kodak lenses
> lately out of pure coincidence. A 170mm f6.3 Tessar in a
> Compound, a 6 3/8 inch Anastigmat in a barrel, and a 80mm
> Anastar on a Kodak Reflex II TLR. I am very impressed
> with all 3 of them for sharpness and contrast (lack of
> coating considered where appropriate) even wide open. All
> but the Anastar are uncoated. All exhibit excellent OOFA
> qualities too. I now have all I need, so I'll tell
> everyone. Don't be afraid of buying them because they're
> so cheap. I am now a believer, Kodak made darn good
> lenses.
> Richard, and anyone else, I've done some portrait work
> with this 6 3/8 Anastigmat, and frankly I just love it.
> It softens just slightly wide open and generally gives
> very pleasant skintone rendition. I've never heard
> anything good said about Tessar designs for this purpose,
> with Heliars and such getting all the ink. Is there some
> technical reason for Tessars to be poopoo'd for
> portraiture?
>
Tessars work fine for portraiture. Many lenses have some
residual spherical aberration when wide open. Spherical
tends to soften highlights by spreading them out resulting
in a sort of halo effect. The problem with unsymmetrical
lenses, like the Tessar, is that they also tend to have coma
or oblique spherical (similar to coma but from a different
source). This makes tear drop shaped smears out of the
highlights which most people find unpleasant. These
aberrations are absent at the center of the image but become
progressively visible as the angle increases. Both disappear
rapidly with stopping down. Spherical, OTOH, is constant in
all parts of the image.
Kodak made two series of Kodak Anastigmat lenses. The
Series 30 are Tessars, the Series 70 are four element air
spaced of the generic type sometimes called a Celor or a
Dialyte. A great many very fine lenses are of this type, the
Apochromatic Artar and Goerz Dogmar being examples. They are
limited in coverage and have 8 glass-air surfaces leading to
flare if not coated, so they were never as popular for
general use as the Tessar. Most of the Kodak lenses are
similar to the Dogmar in being not quite symmetrical. The
shifting of a little power from one cell to the other helps
to optimise the lens for distant subjects. The last of this
series was the No.70 K.A. which became the f/7.7, 203mm
Ektar. The 100mm Enlarging Ektar is also of this type. The
other Series 70 K.A.s were discontinued around 1947, I don't
know the exact date. Around this time Kodak also changed the
names of all the remaining K.A. lenses.
Some of these lenses became Ektanons, some other names.
The front element focusing lenses previously known as Kodak
Anastigmat Special became Anastars, lower quality, three
element lenses became Anastons.
The Anastar in the Kodak Reflex is a four element air
spaced type, the one in the f/3.5 rangfinder version of the
Kodak 35 camera is a modified tessar. The rear component of
this lens has the order of powers reversed from the normal
Tessar. A Kodak designer, I can't remember whether it was
Aklin or Altman now, says this results in better performance
where high index glass is used.
Some of Kodak's cheaper lenses are quite remarkably good.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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