Archived posting to the Leica Users Group, 1997/02/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I don't know whether all lamps dissipate about the same proportion of energy in the IR range, but that seems to be the base assumption here (it actually surprises me a lot about fluorescents). That said, I realized that what has confused me while reading this discussion is that David is talking about lumens, which are a very weird unit that was made up just for humans. Lumens are a measurement of light at 5.4 x 10^14 Hz, which is a cool yellow that we happen to perceive as particularly bright. Even if all lamps dissipate about the same amount of energy in the IR range and the rest in the visible spectrum, it is possible for two lamps that dissipate the same total energy to have very different luminous efficacies because they can produce different-colored light. Which I think is what David was saying but I didn't understand it because I was thinking of lumens as measuring all visible light and was wondering where the rest of the energy was going (gamma rays? sound?).