Flash Power - DPChallenge Forums

Canon EF 100mm f/2.8 USM Macro

02/26/2007 04:07:05 PM · #1

Can someone with a flash meter tell me how many more stops powerful an Alien Bee 800 or 400 Unit at full is compared to a shoe or handlemount flash like the SB-800, 580ex, vivitar 285, or sunpak 555 at full power?

Spork99

OM System OM-1

02/26/2007 04:18:32 PM · #2

Not sure exactly, but I have no problem getting f22 at 10' out of one head using my Speedotron pack on low power (400Ws) shooting into a white umbrella.

So, the answer is probably several stops rather than 1 or 2.

What exactly is it you're trying to figure out?

nicklevy

Canon EOS-350D Rebel XT

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

02/26/2007 04:19:47 PM · #3

According to both the alienbee and canon web site. Given the specs of both, the AB400 should be around 2x the power of a 580EX II.

02/26/2007 06:23:54 PM · #4

Originally posted by nicklevy:

According to both the alienbee and canon web site. Given the specs of both, the AB400 should be around 2x the power of a 580EX II.

So thats really only a one stop difference, correct?

For the question regarding what I'm trying to do, I want to overpower the sun by a stop or two using a light modifier. I have no problem shooting in the full sun with ambient underexposed by a stop or so, but the flash is harsh.

02/26/2007 10:11:32 PM · #5

eh?