From 92a5a6fb73675168876ef9408c93ad5f95a28840 Mon Sep 17 00:00:00 2001 From: mattmcw Date: Wed, 27 Jul 2022 14:03:04 -0400 Subject: [PATCH] Added more sections but still in progress. Committing work without compiling new pdf --- NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md | 94 +++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) diff --git a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md index 477e9a1..52464f3 100644 --- a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md +++ b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md @@ -840,3 +840,97 @@ Any way, the two films ehare one exposure adjustment and filtration. When films will be physically bipacked they should first be wiped with a lubricating film cleaner. This is good practice for all optical printing when delicate originals receive heavy handling. + +## EXPOSURE COMPENSATION + +For superpositions from random pictorial originals: + +For double exposures, the typical exposure adjustment is one stop of decrease from normal, during each exposure. + +> With this adjustment a double exposure of picture A with picture A ie the same as a single normal exposure of A. + +For bipacks there is no recipe. +Exposure adjustment is extremely dependent on which tones coincide with +which. +The adjustment is an increase from normal. +In ignorance of the originals (why?) and ignorance of the intentions (why?) guess 2 1/2 stops increase. + +> No exposure adjustment can make a bipack of picture A with picture A the same as picture. A printed the same. But a gamma 1/2 bipack of +picture A with picture A is the same as picture. + +## SPECIAL ORIGINALS +For superpositions not from random pictorial originals tones might not combine at all. +One image might fall on the other's black, or clear, and exposure compensation is different, perhaps unnecessary. + +With special, rigged, originale superposition is not image combination in the earlier sense but image apportionment--implantings and supplantings. + +The rules of tone combination still apply, but trivially, and a simpler logic prevails. +Double exposing from positives, where one image is black the other image appears, unaffected by the double exposure. +Where one image is very light it appears, hardly affected by the double exposure. + +Double exposing from negatives, where one image (the picture, not the film) is clear the other image appears, unaffected by the double exposure. + +Bipacking, where one image is any even tone, the other image appears, unaffected except for brightness. +The clear parts of one film are windows for the other film. +But it is possible, with enough extra exposure, to force one image through the blackened window of the other. + +The most extreme cases of rigged originals involve high contrast masks, discussed below. + +## TEXTURING + +In a bipack, an image.of a plain white eurface, showing just its texture, imparts this texture to the other image. + +## MULTI-EXPOSURE + +Triple, quadruple, etc. multiple exposures are made similarly to double exposures. +If there would be 5 exposures from the same or nearly the same original, then each should receive 1/5 normal exposure. +From Chart C, 1/5 of full shutter equals `ND.70` compensation. +More likely the originals are special, and the compensation less. + +## MULTI-PACK + +Tripacks, quadripacks, etc. are unmanageable in simple optical printers. +For such effects intermediate prints must be made. +For example, to quadripack A,B,C,D make printed bipacks of A with B and C with D and bipack these two prints. +The order of the originals doesn't matter. + +## NATURAL SUPERPOSITION + +Of the three types only (1), the double exposure from positives, corresponds to possible camera original. +An original double exposure made from two real scenes is practically the same as a printer double exposure made from positive images of the scenes. + +Type (2), the double exposure from negatives, is an artifact of the "log linear" response of negative films. + +Type (3), the bipack, is an artifact of the transparency of film images, at least one of them. + +Type (1) is nature's super. +Pressing one eyeball produces such superpositions. + +## FLASHING + +Double exposing an image with no image -- sere light -- lightens +(or with colored light and color print filma, colors) the blacks +and darker tones while having little effect on middle tones +and even lese on lights. It is8 not a true method of contrast +reduction. + +Sepia toning can be simulated by both color flashing and color +filtering when printing B&W original onto color reversal print filr +A healthy yellow, magenta, or cyan flash when printing onto color +reversal film yields, respectively, the yellow, magenta, or cyan ~ +image, as if this dye layer were prised from the original film. +There ie no photographic method for unflashing a flashed image. +There is image addition (double exposure} and image pultipliocation +(Dipack) and even image division (bipack of positive with +negative), but no image subtraction. + +CONTRAST ADJUSTMENT Gammas add or subtract in a bipack, so bipacking + +can adjust contrast. A bipack (printed gamma 1 or +Viewed raw) of an original with its duplicate is +like a double contrast original.