Film grain
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Film grain or film granularity is the random optical texture of processed photographic film. Film grain develops due to the presence of small particles of metallic silver, or dye clouds, developed fro
Photomicrograph of grain of different photographic plates
Film grain used for artistic effect
Rallycross car pictured on Agfa 1000 RS slide
Detail of the same photo to show the grain better
Film speed
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Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system introduced in 1974. A
Film grain
…halide grains play crucial role in the image characteristics and exposure behavior. There is a tradeoff between the crystal size and light sensitivity (film speed); larger crystals have better chance to receive enough energy to flip them into developable state, as they have higher probability of receiving several…
This film container denotes its speed as ISO 100/21°, including both arithmetic (100 ASA) and logarithmic (21 DIN) components. The second is often dropped, making (e.g.) "ISO 100" effectively equivalent to the older ASA speed. (As is common, the "100" in the film name alludes to its ISO rating.)
A box of Agfacolor Neu with the instruction "expose as 15/10° DIN" (in German)
Weston Model 650 light meter from about 1935
Early Weston Master light meter 1935–1945