[5] Variations of the technique have also been used for scientific purposes, in shadowgraph studies of flow in transparent media and in high-speed Schlieren photography, and in the medical X-ray.
William Henry Fox Talbot called these photogenic drawings, which he made by placing leaves or pieces of lace onto sensitized paper, then left them outdoors on a sunny day to expose.
[20][21] The relative ease of access (not needing a camera and, depending on the medium, a darkroom) and perhaps the interactive to the point of feeling incidental[22] nature of creating photograms[23] enabled experiments in abstraction by Christian Schad as early as 1918,[24] Man Ray in 1921, and Moholy-Nagy in 1922,[25] through dematerialisation and distortion, merging and interpenetration of forms, and flattening of perspective.
Some argue that he was the first to make this an art form, preceding Man Ray and László Moholy-Nagy by at least a year or two,[26] and one was published in March 1920 in the magazine Dadaphone[27] by Tristan Tzara, who dubbed them 'Schadographs'.
I simply laid a glass negative on a sheet of light-sensitive paper on the table, by the light of my little red lantern, turned on the bulb that hung from the ceiling, for a few seconds, and developed the prints.
"In his photograms, Man Ray made combinations of objects—a comb, a spiral of cut paper, an architect's French curve—some recognisable, others transformed, typifying Dada's rejection of 'style', emphasising chance and abstraction.
[31] The shapes became the matrix for an abstract painting to which he applied colour and added drawn geometric lines to enhance the dynamics, exhibiting them at the Galerie L'Equipe in Paris in 1938–1939.
A contact-print onto a fresh sheet of photographic paper will reverse the tones if a more naturalistic result is desired, which may be facilitated by making the initial print on film.
Alice Lex-Nerlinger used the conventional darkroom approach in making photograms as a variation on her airbrushed stencil paintings,[48] since lighting penetrating the translucent paper from which she cut her pictures would print a variegated texture she could not otherwise obtain.
Direct sunlight is a point-source of light (like that of an enlarger), while cloudy conditions give soft-edged shadows around three-dimensional objects placed on the photosensitive surface.
The cyanotype process ('blueprints') such as that used by Anna Atkins (see above), is slow and insensitive enough that fixing an impression on paper, fabric, timber or other supports can be done in subdued light indoors.
[26] Conventional monochrome or colour, or direct-positive photographic material may be exposed in the dark using a flash unit, as does Adam Fuss for his photograms that capture the movement of a crawling baby, or an eel in shallow water.