sensitometer

A device used for measuring the sensitivity of photographic film to light.

A similar device for measuring the sensitivity of eyes to light.

An apparatus or device of any kind for testing or determining the degree of sensitiveness of photographic films, emulsions, etc.; also, loosely, the sensitiveness of a plate (generally expressed in numbers) as indicated by a sensitometer.

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.

An instrument used to measure the sensitivity of photographic film to light

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