600EX-RT VS. BX500Ri

I'm just trying to figure out the difference in power and how many 600EX's would it take to equal one BX500Ri on terms of power. Can someone please explain? Thanks

depending who answers a 600EX is generally considered to be in the range 50 -75Ws (opinions differ)

so between 10 and 7 600EX's to equal a BX500 as an approximation

though, for the cost of five 600EX one could purchase a profoto B1.
a very nice piece of kit

Thanks.

Lowest setting of the BX500Ri is about 600ex-rt at half power (give or take).
Highest settings is about 5-6 times brighter.

It will mainly be important in large places. If shooting close or smaller darker places, you can "get away with" the 600ex-rts.

Coming up with 'watt-second equivalence' for a spedlight is a rather futile effort, for a number of reasons.

• We know that manufacturer ratings of Guide Number for speedlights is about +1EV optimistic.
  
• the angle of coverage of comparison of the Canon really needs to be stated as 'with normal lens', as that corresponds to the 48 degree AOV stated with the BX500 output of f/90 at 1m (GN90 in meters, or about GN295 in feet).
  

• The Canon GN rating for a 'normal lens' is GN138, factored down (for optimism in rating) to about GN99.
  
• So at 10', Canon = f/10 and the Elinchrom = f/29, or a bit more than +3EV difference.