PLASA Photometric Standard Now in Public Review

A draft standard that would change how we measure the output of LED luminaires is now posted for public review at http://tsp.plasa.org/tsp/documents/public_review_docs.php. The proposed new standard, BSR E1.48 - 201x, A Recommended Luminous Efficiency Function for Stage and Studio Luminaire Photometry, specifies an luminous efficiency function V(lambda) based on recent human eye response research. Most light meters in use today use the 89-year-old CIE 1924 V(lambda) function. It's wrong, particularly at the long and short wavelengths, so meters using it significantly under-report the output of RGB LED luminaires and any other sources that put out significant energy in the extreme ends of the spectrum.

The draft E1.48 standard is available for review now. The review runs through September 2, 2013. The review will be over and the links to the draft document will disappear when the "Review End Date" of September 3 is reached.