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Topic: Mag Oxide
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John Pytlak
Film God
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Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 08-02-2001 01:49 PM
Found this interview with Thomlinson Holman, which hints at a significant formulation change: http://www.mel-lambert.com/Writer/Interviews/MIX.Tom_Holman.html "Did you continue to work with Dolby on the evolution of its 4-track 35 mm systems and 6-track, 70 mm formats? To a certain extent. What we did on "Return of the Jedi" was change the magnetic oxide. When we looked at the magnetic oxide they were striping on 70 mm prints in 1983, it was equivalent to Scotch 102 from the early Fifties! The problem was there was only one vendor, but a second vendor was interested and had bought up the old MGM striping plant. We went with them because they were striping a much better oxide. The interesting thing was that the difference you got in headroom was 11 or 12 dB -- a major improvement. "Jedi" was pretty good sounding on 70 mm, but there were still a few orchestral passages where you could hear IM. What was happening was that the accumulated distortion over all those [dubbing] generations had suddenly become audible; it wasn't audible on the [print] master but became obvious on the releases print -- it was just one generation too many. By the next year we pushed 3M into making much better mag-film stock for the post-production generations. When we had got to "Indiana Jones and the Temple of Doom," where was an incredible passage for IM where the bass drum is banging with choral music above it -- the [new formulation] passed the test, and it did not intermodulate audibly." ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 08-03-2001 06:32 AM
Other things changed in 1983 too...The 70mm track widths (how wide the head gaps are, not the actual striping) got wider and the reference level went up too. That is, we had a true 185nWb/m reference level. In recent tests I performed...the new reference level amounted to about 7.5dB in increased level on the film for Dolby Level. 1983 (Jedi) was a pivotal year for 70mm magnetic. I believe the 35mm magnetic levels and track widths changed as well.The original striping facility was Magnacraft. I believe CFI is the new facility Tom spoke of. Steve ------------------ "Old projectionists never die, they just changeover!"
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