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p.1 #1 · p.1 #1 · Help needed comparing Olympus flash guide numbers | |
Hi,
Can someone explain to me how to compare flash guide numbers, specifically Olympus flashes? For instance, here are the specs for some Olympus flashes:
FL-LM2 - 33' at ISO200 at 50mm
FL-300R - 28' at ISO200 at 35mm
FL-600R - 50' at ISO200 at 8mm
FL-36R - 65' at ISO100 at 24mm
Fl-50R - 79' at ISO100 at 24mm
Different distances, ISO and focal lengths are specified in the guide numbers. So what formula do I use to determine the output for each of these flashes for a given distance, ISO and focal length. For instance, how would I determine the F stop to use for each of these flashes at 50mm (35mm format, so 25mm m4/3 lens), 10 feet away at ISO 100? Also, how does shutter speed affect on the situation?
I found the general guide number formula of GN=distance* f-stop but I don't see how this formula works when determining if a flash has enough power to do the job in a specific situation.
Thanks for the help.
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