What is "sensitometer"

Sensitometer \Sen`si*tom"e*ter\, n. [See Sensitive; -meter.] (Photog.) An instrument or apparatus for comparing and grading the sensitiveness of plates, films, etc., as a screen divided into squares of different shades or colors, from which a picture is made on the plate to be tested.

n. (context photography English) An instrument used to measure the sensitivity of photographic film to light.

n. a measuring instrument for measuring the light sensitivity of film over a range of exposures