Thursday, May 8, 2008

product of illuminance and time

Unit of measurement: lux second [lx s]Exposure H is defined as the product of illuminance and time (at constant illuminance).H = E * t E = illuminance (in lx)t = time (in seconds)Exposure meters are used in photography to determine the ideal exposure time for a given illuminance. Exposure is also an important factor in assessing safe display times for light-sensitive exhibits in museums.

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