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Add emulsion position section

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Matt McWilliams 2022-07-26 15:45:57 -04:00
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NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
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@ -303,3 +303,49 @@ Determine how much vertical adjustment separates their framelines.
Make that puch adjustment to the aimframe setup.
The framelines of the original can always be eliminated from the print by setting the magnification slightly greater than 1.
## EMULSION POSITION
A priori, a film of an alphabet could be any of these eight ways.
**![Graphic depicting eight strips of film with letters F and G oriented and labelled](#)**
Each sketch shows emulsion facing out.
For double perf film there are only four ways.
The a and b ways become the same.
Camera original is (IIIa).
A contact print from camera original is (Ib).
A contact print from a contact print from camera original is (IIIa) again.
Etc.
All the others are shams--either optical printing errors or else films of alphabets somehow reversed.
Given a double perforated (I), (II), (III), or (IV) it is easy to make a double perforated optical print which is any of the four.
Single perforated films are a pain in the side.
Given, for example, (IIIa), it is possible with a usual optical printer to make either (Ib), (IIb), (IIIa), or (IVa), but none of the other four.
These could be made via a double perforated intermediate.
With a prism or other image rotator, or a special reversed gate, it is possible to convert any of the eight ways to any of the eight ways.
Figuring out how to do these is a good exercise for the student.
The two non-sham emulsion positions are sketched again,
this time with emulsions facing in shown dotted.
**![Two graphics depicting CAMERA ORIGINAL and CONTACT PRINT FROM CAMERA ORIGINAL](#)**
Notice that when pictures "read right" single perfs are on the left, and "before" is above.
Notice that camera original reads right with emulsion facing away.
Contact print of camera original reads right with emulsion facing toward the viewer.
Except when optical printing is done in alliance with contact printing, it is usual to maintain emulsion position through all optical printing steps.
Starting with camera original each generation is again (IIIa).
For this there is a simple rule.
> To reproduce the emulsion position of the original, insert it in the printer gate with emulsion away from lens, heads up, running upward.
Optical printing "through the base" does not degrade image quality.
The optical printer can also imitate the contact printer, if the original is inserted in the printer gate with emulsion toward the lens.