Quote Originally Posted by Rafal Lukawiecki View Post
Unfortunately, my flash meter, L-508, only shows f stop value, there is no readout in lux-sec.
Make a reading at your box with the flat diffuser. Count the number of stop from f/1.0 for example if it displays 5.6 3 then 5.6 is 5 stops from f/1.0 plus .3 then it's 5.3
The Lux.second is (2^5.3)*2.5=98 lux.sec