A handbook of photography in colours / Thomas Bolas, Alexander A. K. Tallent, Edgar Senior.

  • Bolas, Thomas.
Date:
1900
Catalogue details

Licence: In copyright

Credit: A handbook of photography in colours / Thomas Bolas, Alexander A. K. Tallent, Edgar Senior. Source: Wellcome Collection.

    100/458 (page 78)
    complementary to the above spectral blue will be a greenish-yellow ; these complementaries must over-lap as little as possible, or in other words they must correspond to separate parts of the spectrum or the prints will be muddy and incorrect in colouring. Captain Abney’s paper is to be found in the Journal of the Royal Photographic Society, March 1899, page 192. Captain A bney on plates for the most perfect effect. Ordinary, or unstained plates are, Captain Abney points out, the only plates which will most perfectly reproduce all spectral tints, as every part of the spectrum acts on the ordinary plate, although with very unequal intensity ; still without dark clouds or patches in the spectral image, a point Captain Abney illustrated by projecting upon the screen the spectrum as photographed upon various colour sensitised plates and upon ordinary plates. Obviously the ordinary plates must be used with sufficiently intense screens corresponding to the colour sensation curves and the relative exposures for the three negatives will be about as follows : “ Red ” negative 100 ; “ Green ” negative 8 ; “ Blue ” negative 1. Obviously for ordinary com- mercial work, which of a necessity involves somewhat of a compromise with scientific principles, colour sensitive or stained plates will be used in order to lessen the above wide difference of exposure for the three negatives.