Hi, Neo-Tech,
Welcome to CPF!
I don't think you can do a direct conversion.
WS/Joules is the amount of energy stored in the capacitor.
Candela is the amount of light in a particular direction.
Too many factors influence the conversion of joules to candela for us to give a conversion factor.
Among those factors are:
--efficiency of the discharge circuit (how much energy is lost in the wires),
--efficiency of the flash tube (how many joules produce how many lumens)
--design of the reflector (how many lumens produce how many candelas in the direction you're measuring
For example, I have two lights I'm playing with (both incandescent, both alkaline powered). Light A produces approximately slightly less than 2x the lumens of light B while light B produces at least 6x the candela of light A!
Another factor with strobes--and I'm not sure where it kicks in--is that peak lumen output is a factor over time. For example, if the same energy in the capacitor was discharged over 1ms to produce 100k lumens, and then the same energy was discharged over 0.1ms it MIGHT (if all was linear and with arcs I'm never sure) produce a peak of 1M lumens.
Then we get into the metric of how our eye responds to pulses--the integration time.
Aaargh.
Can you perhaps run these two side by side and look at them <smile>.
Cheers,
Richard
