Full title: British Imperial Trans-Antarctic Expedition, 1914-1917 / Paget plates by Frank Hurley
Author/creator: Hurley, Frank, 1885-1962.
Call Numbers: ON 26
Record Identifier: nmQd03Pn
Formats: Pictures, Photographs
Contents: 32 photographs (2 boxes) - 12.0 x 16.3 cm - colour glass phototransparencies (Paget plates)
The Paget Colour Plate system used by Hurley was not like today's colour film. It used a ruled set of colour lines, called a screen, sandwiched with a standard black and white glass half plate negative. The subject was exposed through the colour screen, which acted like a series of colour filters, onto the black and white negative. The negative was reverse processed into a positive transparency and placed back in contact with the screen, giving the effect of a colour photograph.
NOTE: With time, many of the screens have shrunk at a different rate to the black and white positive, so that the image now has a strange magenta/green colour shift that does not resemble the original colours. On the other hand, some of Hurley's Paget plates seem to have the correct rendering.
TECHNICAL DETAILS OF PAGET COLOUR PLATES: Early colour processes were based on introducing minute colour filters into a black and white emulsion. For instance the Autochrome system used minute potato starch grains, one third dyed red-orange, green and violet on a glass plate. Red light would pass through a red starch grain and give a black dot on the negative. Reverse processing would then produce a clear spot. When the glass plate was held up to the light, a red spot would be seen, corresponding to the original light.
Several colour screen processes, using machine ruled lines on the emulsion, were introduced before WWI.
Geoffrey Whitfield of London devised a system in which the screen was produced on a plate first dyed red. The surface was covered with parallel lines printed in a water resistant material and the plate bleached. The clear spaces between were dyed green and a second pattern of cross resist lnes was printed, followed by a second bleach. The clear spaces remaining were dyed blue, giving a pattern of two blue squares to each red and green square. The elements were about 1/300 inch in size..They were marketed as Paget Colour Plates in April 1913. Exposures were about 1/25th second at f4. It was possible to buy separate screens, which were sandwiched with the black and white plate before exposure and realigned after processing.
Colour screen processes fell out of favour in the 1920s, when the price of screens became prohibitive. Naturally, enlargement of any colour screen process soon reveals the pattern of lines or, in the case of an Autochrome, the potato starch grains.
-- Curator of Photographs, Mitchell Library, 2001
5 x 4 positive film colour transparencies (reproductions) separately located at the Colour Transparencies films copy sequence at ON 26.
Digital order no:Album ID : 823227
MMS ID: 110315564