> > >So there is no way to make a *generic* conversion formula >between Lumen and Candela. And if so, why have both in the >first place ? > Thank Jan-Erik I was comparing LEDs from different manufacturers and they were giving the different specs. But your explanation made clear what has actually bothered me for a while. I can work with that. Quentin -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu