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Topic: Anyone ever seen nostril pixie-dust on a print?
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 03-03-2000 06:43 AM
Sounds like a classical form of heat damage from "hot spotting" the lamp. The darker areas of the print absorb much more radiant energy. If there is a "hot spot" due to misalignment of the lamp, when the dark area (e.g., dark nostril) crosses the area of most energy, the dark areas heat up enough to damage the film. The excess heat causes the emulsion to delaminate internally, causing "voids" which refract light. These "voids" often take on a crystalline or "snowflake" pattern when a single frame is viewed. Looking at the film projected at 24fps, the damaged area seems to "crawl" with these tiny patterns.A misaligned lamp that is "hot spotted" may also cause an opalescent spot in the area of damage, especially in very dark or black scenes. Look at dark scenes in the print by reflected light --- if you see a colored "spot" in the same area of each frame, you need to check lamp alignment and back off on the focus of your lamp. The "spot" will usually be magenta-colored when viewed from the emulsion side, and greenish-yellow when viewed from the back side. Unfortunately, the print has been permanently damaged by the misalignment/misfocusing of the lamp --- correct it as soon as possible, before another print is damaged. Any lamp 2000 watts or larger should only be used with infrared heat filters or a dichroic mirror. ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Professional Motion Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 03-04-2000 02:57 PM
The title of the feature would be useful information. Although Kodak Vision Color Print film is very resistant to heat damage, it is very important to use proper heat filtration and not "hot spot" the lamp, especially with large lamps.Because B&W (silver image) prints absorb much more infrared energy, they are more sensitive to excessive radiant energy. Some recent color prints (e.g., "Seven", "Evita", "Saving Private Ryan") have used a "silver retention process" that deliberately leaves some silver in the image area to achieve darker blacks and a higher-contrast desaturated look. Because of the retained silver, they will be more sensitive to heat damage. ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Professional Motion Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
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