1600 watts
Some enterprising Media Diploma studies students interviewed the owner of the oldest cinema in England [ 5 minutes, 67Mb, mpg, excellent sound ] – The Electric Cinema in Birmingham.
One throw-away comment as the proud proprietor was demonstrating his projection room: 1600 watts of light – each 1/24th of a second, a 35mm movie film frame gets 1.6 Kw of light passed through it, I guess in four blasts as most film projectors use a ‘maltese cross’ arrangement to chop the 1/24th of a second into 1/96th of a second to reduce flicker.
A movie film frame sits horizontally across the film (18mm by 24mm) so that is something like 3.7 watts per square millimetre of film stock, or around 154 milli-Joules of light energy for each square millimetre of film. Serious heat – no wonder they need infra-red filters.
