As well you should be worried. An output measured in lumens would be better described as "light power." If multiplied by a time duration (or if variable, integrated over the run time), it would be "light energy." In any case, it derives from radiant power output vs wavelength multiplied by the CIE luminosity function which estimates how well the human eye senses light at each wavelength.
________________________________ From: Pat Naughtin <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Sun, October 24, 2010 3:34:30 AM Subject: [USMA:48705] Re: flash light standard On 2010/10/24, at 06:31 , m. f. moon wrote: I recently bought a new mini maglite led flashlight marked with a set of parameters labelled FL 1 Standard. These parameters were all in metric and included "243 cd, 31 m, 9 lumens, 1 m" . I found by google search FL 1 standard the new standard from NEMA which defines all of this and more. Some surprise to me -- so look it up it is interesting. > > >m moon Thanks for the reference Marion, I found this YouTube site to be a good explanation for the light unit naive (like me): http://www.youtube.com/watch?v=aO_l5ciKsPg It's not all metric but clearly they are heading in the right direction. (But I was a bit worried about "light energy" being measured and quoted in "lumens". When I think energy I think joules!) Cheers, Pat Naughtin Author of the ebook, Metrication Leaders Guide, see http://metricationmatters.com/MetricationLeadersGuideInfo.html Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/ to subscribe.
