[pure-silver] Re: Agfa Paper Equivalent
- From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 10 Jun 2008 00:28:52 -0700 (GMT-07:00)
-----Original Message-----
>From: Bogdan Karasek <bkarasek@xxxxxxxxxxxx>
>Sent: Jun 9, 2008 8:48 PM
>To: pure-silver@xxxxxxxxxxxxx
>Subject: [pure-silver] Re: Agfa Paper Equivalent
>
>WOW!
>
>Thank you, Richard, that was a great little jewel of photo history!
>
>So Tri-X jumped from 200asa to 400asa, or was it around then?
>On that same item, when did XX morph into Tri-X?
>
>Cheers,
>Bogdan
>
As to speeds, exactly. I don't remember when Tri-X as roll film became
available, it think it was by 1958 but it had been available as sheet film
since the 1940's.
Super-XX was rated at ASA 100 by the old system and became ASA 200 in the
new system.
Kodak had been publishing "Kodak Speeds" in their data sheets for some time
before the ASA system was adopted (1943 I think). These speeds are equivalent
to modern ISO speeds when divided by two and to the old ASA speeds when divided
by four.
Loyd A. Jones work has become undeservedly obscure. He researched the
problems of tone rendition and practical film speed for some thirty years and
published copiously. I think Kodak's whole philosophy of what a good print
should look like was based on Jones work. I will find some citations and post
them.
When C. E. Keneth Mees founded the Kodak Research Laboratories, in 1912,
he decided that its publications should appear in established, peer-reviewed
journals rather than a house organ. This gave the labs work immediate
credibility but can make tracking down citations difficult. However, much of
Jones, and his associates, work can be found in the _Journal of the Franklin
Institute_, the Journal of the Society of Motion Picture Engineers (now the
Society of Motion Picture and Television Engineers), the _Journal of the
Optical Society of America_, the _Journal of the Chemical Society of America_
and _Photographic Science and Engineering_, among others.
A good bibliography and summary of his work on tone rendition and
sensitometry, at least up till the time of its printing, can be found in
_Theory of the Photographic Process_ revised edition, C.E.K. Mees.
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
Los Angeles, CA, USA
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