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Xenon short-arc lamp: Difference between revisions

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===Measuring Luminance===
===Measuring Luminance===


The [[Society of Motion Picture and Television Engineers|SMPTE]] specification is 16fL ([[foot lamberts]]) with uniform illumination across the projected area without film in the projector (open gate). Because spherical widescreen formats (1.66:1, 1.85:1) are the least light efficient, and 1.37:1 and Scope are more light efficient, you can split the difference with 15fL for [[Aspect ratios|1.85:1]] and 17fL for [[Aspect ratios|Cinemascope]].
The [[Society of Motion Picture and Television Engineers|SMPTE]] specification is 16fL ([https://en.wikipedia.org/wiki/Foot-lambert foot lamberts]) with uniform illumination across the projected area without film in the projector (open gate). Because spherical widescreen formats (1.66:1, 1.85:1) are the least light efficient, and 1.37:1 and Scope are more light efficient, you can split the difference with 15fL for [[Aspect ratios|1.85:1]] and 17fL for [[Aspect ratios|Cinemascope]].


If you’re checking luminance through the port glass with your meter subtract 1~2fL. It’s always best to take your final readings in the auditorium itself.
If you’re checking luminance through the port glass with your meter subtract 1~2fL. It’s always best to take your final readings in the auditorium itself.

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