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Re: Lumens per liter

George Booth <booth at frii_com> wrote:

> >Date: Wed, 6 Dec 2000 08:53:49 -0700 (MST)
> >From: "Roger S. Miller" <rgrmill at rt66_com>
> >Well, all those details are far too involved to constitue a "rule of
> >thumb".  I suspect that the 30-50 lumen per liter rule is based on nominal
> >lumens -- i.e. on the lumen rating of the light source.  If you need to
> >base something on actual lumens then probably you're better off getting a
> >meter, measuring lux and converting to lumens.
> Gosh, once you have a lux meter, why go back to goofy lumens? That's sort 
> of like figuring out how many gallons of gas you put in your fuel tank by 
> dividing miles traveled by what your car thought it did in miles per 
> gallon. Why not just read the gas pump meter? Lux is what you really want - 
> the actual intensity as produced by the lumens coming form the bulb and 
> bouncing off the reflector.  Hey you can even tell how bright it is at the 
> bottom after all the shading and light piping takes place. Cool!

OK, but I guess the idea here is to have an estimate of the illuminance level 
*before* you buy/build/design the lighting system. The light meter will
only work with an existing, operational system, not with one still in the 
design phase.

- Ivo Busko
  Baltimore, MD