Pair of flashes for more power...

[rpcrowe]

I am thinking of my surfer shoot at Oceanside, California last year...



It's getting to be that time of year again. However, I'd like to use fill flash for the next shoot. Not really to open the shadows but rather to add a bit of "pop" to the image...

I have a Flashpoint (Godox) Streaklight 360 TTL as well as a Flashpoint Zoom R2 Manual Hotshoe flash... I am wondering about using both of these flashes in tandem (they will do HSS triggered with the Streaklight R2 Trigger). I shot the last event at ISO 400, using 1,250 second @ f/5.6 with my 100-400mm lens extended all the way out to 400mm. The weather conditions in the morning at that time of the year are pretty much the same day to day...

My idea would be to jury rig a mount with these two units in tandem firing off the R2 Trigger. I would be shooting the surfers from the Oceanside Pier which is a bit of a distance from the participants. I has hoping that the combination of the 360 TTL (all I have to concentrate light is the standard reflector) at GN 262 and the Zoom R2 at GN 127 would give me a bit more power than the 360 alone.. I have an older flash extender which was built for the Canon 550EX flash which I could also rig up for the Zoom R2 flash. I think that this would be more of a PITA

I would be using the two flashes on manual, at full power. I am guessing that the surfers average about 50 feet or so from shooting position on the pier.

[Shadowman]

Richard,

I wouldn't advocate using flash on anyone performing dangerous maneuvers but I guess surfers would be used to getting a bit of sun splashed in their faces, a bit tricky to undertake but have you considered using a flash extender, I believe you said you had one? Also, to anyone considering using one, supposedly they can start fires if pointed at the sun for too long, I've read the same warnings regarding lenses.

https://www.amazon.com/Better-Beamer...flash+extender

[apersson850]

If you combine flashes that are rated with guide numbers, then the combined guide number is the square root of the sum of the squares of the guide numbers.
So the combined guide number will be 89 m, assuming you listed them in feet. I assume your values are given in feet?
In which case it will be 291 ft.

[tclune]

Have you considered using a better beamer instead of a second flash?

[rpcrowe]

If you combine flashes that are rated with guide numbers, then the combined guide number is the square root of the sum of the squares of the guide numbers.
So the combined guide number will be 89 m, assuming you listed them in feet. I assume your values are given in feet?
In which case it will be 291 ft.

Anders,
Thanks for posting this formula. I was wondering if there was some way to mathematically figure out the approximate power of a flash combination...