Canon 580 EXIIs and Alien Bees

[Ralph]

How many 580 EXIIs at full power are needed to produce the same effect as one Alien Bee B800 at full power? I can't seem to find a numerical comparison between the two flashes. I asked that because soon I'll buy an Alien Bee and don't know which model to choose. B1600 may be the most powerful, but even at 1/32 can still cause overexposure (theoretically) and the opposite for the B400.

[TakahiroW4047]

I would also like to know. For future references...since I just bought myself a 70-200mm f/4L so I'm just a tinsy-winsy short on cash at the moment [:P]





The stats that they have on Alienbees websites name Ws and Ls, but I have no idea what the equivalent is since all strobes seem to be described in guide numbers??


I currently use my two Vivitar285HV's and dual mount them onto a 43" Westcott umbrella. Highly doubtful, but if that's anywhere close to say even a B400...I just might consider saving myself $500 and get another Vivitar...or two. Quad mount anyone? []

[Jarhead5811]

I've been looking into the same thing.

AlienBees™ Technical Specifications[/b]]



<table width="405" cellpadding="0" cellspacing="0" border="1"]
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<div align="center"]<span style="font-size: 14pt;"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]guide numbers </div>
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<td bgcolor="#87cefa" class="bee"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] B400</td>
<td bgcolor="#87cefa" class="bee"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] B800</td>
<td bgcolor="#87cefa" class="bee"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] B1600</td>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]Standard 7-inch Reflector</div>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] #118</div>
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<td bgcolor="#f0ffff" class="bee"]
<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] #172</div>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]#236</div>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]11-inch Reflector</div>
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<td class="bee"]
<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]#220</div>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"] #320</div>
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<div align="center"]<span style="font-family: Arial,Helvetica,Geneva,Swiss,SunSans-Regular;"]#450</div>
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<span style="font-size: xx-small;"]We get a lot of questions asking, what is the "guide number" of your flash unit? This term is not wholly reliable because it relates more to the angle of the reflector than to the actual amount of light produced. For example, a flash unit with a given amount of light output will register a much higher guide number (f-stop at 10') if it has a narrow angle reflector (for telephoto lens) than if it has a wide angle reflector. But the actual amount of light is the same in both cases&hellip;it just covers more area with the wide angle reflector (at a lower guide number). In comparing flash units, the max GN of a flash unit is usually given for ISO 100 film. When it comes to choosing a flash unit, you have to be careful, as these measurements can be altered. It is common practice within the flash unit industry (for marketing reasons) to provide the max GN at the smallest coverage, as this will provide the longest focal length. Such a focused flash unit is more powerful, which produces a higher Guide Number, implying a more powerful output. Therefore, the max GNs of different flash units are usually not directly comparable. Studio flash units are designed to be used in many different configurations, with different accessories. The angle of coverage will be different in each case as will be the achieved guide number for a given amount of emitted light. As merely an indication of output, we publish the max guide numbers, noting that they are not true measurements of what you can do with our lights, as the real output will be determined by how you choose to modify the light.
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Click here to go to the AlienBees&trade;web site to see this in context.

[Jarhead5811]

I found [url="http://speedlights.net/compare-speedlight-specs/?model=580EX+II&amp;model2=285HV]this[/url] site looking around on Strobist.com's Flickr forum.


[url="http://speedlights.net/compare-speedlight-specs/]http://speedlights.net/compare-speedlight-specs/[/url]


[quote=Ralph]


How many 580 EXIIs at full power are needed to produce the same effect as one Alien Bee B800 at full power?
<div style="CLEAR: both"]</div>
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Does this make enough sence for someone to hazard a guess?


Somewhere between 4.8 and 8.9?


The whole flash zoom thing makes them very hard to compare. If only you could find the...oh, heck I don't know I'm over my head...Anyone help us?

[peety3]

The whole flash zoom thing makes them very hard to compare. If only you could find the...oh, heck I don't know I'm over my head...Anyone help us?
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Isn't that the truth!


I think I've heard the top-of-the-line flashes (Canon and Nikon) referred to as 50ws, so assuming the B400's 160 true WS rating is correct, it takes 3.2 580s to compare to a B400, 6.4 580s to compare to a B800, and 12.8 580s to compare to a B1600. But I'm no expert...

[TakahiroW4047]

Isn't that the truth!


I think I've heard the top-of-the-line flashes (Canon and Nikon) referred to as 50ws, so assuming the B400's 160 true WS rating is correct, it takes 3.2 580s to compare to a B400, 6.4 580s to compare to a B800, and 12.8 580s to compare to a B1600. But I'm no expert...

I guess that would explain the ~20lbs Vagabond battery pack. That's quite some power [:O]


Thanks for the info everyone!!! []