The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Hauron, and consists in making two of the coloured elements of the three-colour set correspond to one of the pictures of the stereoscopic pair, and making the third element of the three-colour set correspond to the other picture of the stereoscopic pair. The effect of relief is produced by the difference in drawing which exists between one element of the three-colour set and the two other elements of the three-colour set. Amongst the possible methods of carrying out the idea the following may be mentioned: - The right eye looks through a turquoise-blue medium at the red and yellow images superimposed, the blue image being invisible to this eye. When the red pigment lies over the yellow the resulting red-orange appears black to the right eye, as the blue glass will not allow red-orange to pass ; where, on the other hand, there is only the red (purplish-red) pigment, the blue glass allows blue-violet to pass ; where the paper is only covered with yellow pigment, the turquoise-blue glass allows green to pass, green being one element of the yellow pigment. The left eye looks through ruby glass and sees as light and shade that which is printed in blue pigment, and it sees as orange-red that purple-blue which the right eye sees as blue-violet. Thus the right eye receives the impression of green and blue violet, and the left eye the impression 'of orange-red while each eye also receives an effect corresponding to a mono-chrome basis, which gives the requisite drawing in a complete sense. The principle of the anaglyph is applicable to stereo-scopic projection with the magic lantern. According to one method the two pictures of the stereographic transparency are projected upon the same screen by means of two lanterns, but in the course of the luminous rays of each lantern there is inter-posed a coloured glass ; the two colours being complementary to each other, the double and confused image on the screen being viewed by an anaglyphoscope, having glasses of corresponding colour, the stereoscopic effect is obtained. For projection pur-poses, De la Blanchere uses blue and yellow glasses, D'Almeida and Freshwater employ copper-ruby and signal-green. Gold-pink and a yellowish-green is a good combination. A rough test of the suitability of any two coloured glasses is the giving of a maximum of opacity when superimposed, but with the effect of great transparency when one of the glasses covers each eye. In carrying out stereoscopic projection by the anaglyphic method