[pure-silver] Re: Old Kodak Lenses
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 16 Feb 2005 09:26:35 -0500
The Tessar design is quite a good one capable of producing very sharp
images. It's major drawback is being limited to moderate apertures.
For 50 mm lenses such as those used in 35 mm cameras this limits the
maximum aperature to f2.8.
What's more amazing is that these old lenses were designed without the
aid of computers. All done by hand calculation over a period of months
or years.
Jerry
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Gene Johnson
Sent: Tuesday, February 15, 2005 9:48 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Old Kodak Lenses
I would have never thought that lenses this old would be so good.
----- Original Message -----
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, February 15, 2005 6:31 PM
Subject: [pure-silver] Re: Old Kodak Lenses
>
> ----- 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=20
> > 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=20
> > (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=20
> spherical aberration when wide open. Spherical tends to soften=20
> highlights by spreading them out resulting in a sort of halo effect.=20
> The problem with unsymmetrical lenses, like the Tessar, is that they=20
> also tend to have coma or oblique spherical (similar to coma but from=20
> 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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