Alien Bees Guide Number?

Hi Everyone,

 

I have been using a couple of Morris Midiflash units for product photography, but now I am starting to

wish that they put out a little more light. An extra 3 or more stops would be really helpful.

 

I have been looking at the Alien Bees units, but I can't figure out how they compare to my liittle Midiflash

units. The Midiflashes are rated as "Guide Number 55 (@iso 100 in feet)". The Alien Bees 800's are listed

in effective/true Watt Seconds, or in Lumen Seconds.

 

Can anyone give me any idea how to compare those numbers or convert the units?

 

Thanks!

It's on their web site:http://www.alienbees.com/specs.html

 

output measurements B400

 

Standard 7-inch Reflector f11 2/10

 

11-inch Reflector f22

 

48" Silver Bounce Umbrella f8 - f11

 

48" Shoot-Thru Umbrella f5.6 - f8

 

Medium Softbox f11? f16

 

So, the B400 would be GN 125 approx. B800 would be 175 approx.

I think I got the math close enough.

Doug

AB rates the B800 at 172 with the standard reflector, but 320 with the 11" version. 3-5 stops more light than your Midiflash. Of course these are all manufacturers ratings, and they might be optimistic.

The AlienBees web site has aperture settings for all of their lights, each with several types of modifiers (different reflectors, umbrellas, softboxes, etc.) on their web site. I have not seen this complete information on any other competitor's web site.