GN differences - DPChallenge Forums

03/09/2006 07:02:27 PM · #1

How many stops of light are there between a GN of 150, a GN of 140, and a GN of 120? Specifically pertaining to sunpak flashes 555 and 544 and a vivitar 285.

Also, has anyone used both the 555 and 544 flashes by sunpak? Can you comment on the main differences?

Canon RF 24-70mm f/2.8 L IS

03/09/2006 07:52:27 PM · #2

anyone know?

kirbic

Canon EOS R5

03/09/2006 09:07:16 PM · #3

From a GN of 150 to 120 is -0.65 stops, all other things being equal. Given they are the same brand of flash, the numbers might even be comparable, but bear in mind that often GNs are assigned based on different assumptions that render them NOT comparable.

Canon RF 24-70mm f/2.8 L IS

03/09/2006 09:41:48 PM · #4

Originally posted by kirbic:

Thanks, do you know of any sites that do know accurate numbers, I guess manufacturers base their numbres to make the flashes look as appealing as possible. Also, do you know of any sites that have flash durations listed at all powers for popular flashes?

kirbic

Canon EOS R5

03/09/2006 09:49:40 PM · #5

If you find someone who has compiled this kind of info, you're a better googler than I!