AB800/Sunpak 383/580EX measurements

[tim]

I just did a few quick measurements with the lights I have set up to see their relative power, I figured someone else might find them useful. All readings and distances are approximate. I just set up the lights, put them on full power, and pointed my Sekonic L358 at the light with the dome up, and took a reading, ISO100.

NB: since flash coverage is different for each flash these measurements can't really be considered all that accurate.

AB800 (reflector): 1M F32, 2M F16.8
AB800 (big soft box): 1M F11.9, 2M F8.6 (meter is 1/2m from the front of the soft box)
AB800 (45" white shoot thru umbrella): 1M F11.9, 2M F8.0 (meter is 1/2m from the front of the umbrella)
AB800 (45" silver umbrella): 1M F16.5, 2M F11 - meter is 1/2 meters from the strobe
Sunpak 383 (no modifiers): 1M F22.7, 2M F8
Sunpak 383 (45" white shoot thru umbrella): 1M F8, 2M F5.6
Canon 580EX (35mm): 1M F22.3, 2M F8

If anyone wants any other readings I can probably do them this evening.

Note - 1M means one meter, which is about three feet or one yard. F32 means a reading was taken with my Sekonic L-358 light meter at ISO100, and it read that aperture.

[Franko515]

I just did a few quick measurements with the lights I have set up to see their relative power, I figured someone else might find them useful. All readings and distances are approximate. I just set up the lights, put them on full power, and pointed my Sekonic L358 at the light with the dome up, and took a reading, ISO100.

AB800 (reflector): 1M F45, 2M F22
AB800 (big soft box): 1M F16, 2M F11
AB800 (45" white shoot thru umbrella): 1M F16, 2M F12
Sunpak 383 (no modifiers): 1M F22, 2M F16
Sunpak 383 (45" white shoot thru umbrella): 1M F11, 2M F5.6
Sunpak 383 (45" silver umbrella): 1M F11, 2M F8
Canon 580EX: 1M F22, 2M F16 (same as the sunpak).

If anyone wants any other readings I can probably do them this evening.

I am really surpised the shoot through and silver umbrella had the same output at the same distance.

You didnt by any chance do the 580EX II with the shoot through and silver umbrellas did you? Just curious as to the numbers.

Oh and which umbrellas are u using?

Thanks for doing this and thanks in advance for your reply

[Curtis N]

I'm surprised the B800 gave only a stop more than the Sunpak, shooting through the same umbrella. I would expect about a 3 stop difference, based on my own testing with a B1600 and a silver bounce umbrella.

It would be good to know what zoom setting you used on the 580EX for the direct shots.

[Franko515]

I'm surprised the B800 gave only a stop more than the Sunpak, shooting through the same umbrella. I would expect about a 3 stop difference, based on my own testing with a B1600 and a silver bounce umbrella.

It would be good to know what zoom setting you used on the 580EX for the direct shots.

Good catch Curtis, I only looked at the small flashes.

[tim]

I've remeasured everything, this time using a tape measure and with both the Sunpak and the 580EX at 35mm, so things have changed a little. Seems the AB800 is about two stops more powerful than the 383 when using a white umbrella. Remember with the silver umbrella the light travels from the strobe a meter to the umbrella, then another two meters to the meter, but the silver umbrella focuses the light whereas the shoot thru spreads it out more.

I have my 383s powered by sealed lead acid batteries so they charge just slightly slower than the AB800s, both at full power. Pretty impressive from the little flashes. My new skyports have been 100% reliable so far.

[SnlpeR]

can you put two 383s side by side and pop them at full power?

[tim]

I could, but it's not worth the bother as I know what happens - you gain one stop.

[mrandrew]

What is your unit when defining the power?

1M = ?
2M =? F22.7?

[tim]

1M is one meter (for the Americans that's about three feet or one yard). F22 is a reading from a light meter, at ISO100.

[tim]

I suspect my methodology was flawed. The AB800 probably covered a wider area than the hotshoe flashes, I think if I adjusted for light spread the ABs would win hands down. Next time I have them out (which could be a while) i'll check that out.

[Karl Johnston]

I guess I'll be surprised then !

[40Dude6aedyk]

http://www.flickr.com/groups/strobist/discuss/72157609375924090/ shows some other measurements of flash output that might interest folks reading this thread.

http://www.scantips.com/speed.html shows some flash duration results that might interest folks as well.

Both include ABs and some speedlites.