I am new to off camera lighting but I just picked up a 580ex II and I was wondering how much of a difference the 580 at full power is compared to the alienbees 800.
Nickc84 Goldmember  2,064 posts Likes: 80 Joined Jul 2010 More info | Mar 20, 2011 21:58 | #1 I am new to off camera lighting but I just picked up a 580ex II and I was wondering how much of a difference the 580 at full power is compared to the alienbees 800.
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msowsun "approx 8mm"  More info | Mar 20, 2011 22:08 | #2 The Canon 580EX II has a max Guide Number of 190 feet (or 58 meters) when the head is zoomed to 105mm. Off camera flash is often shot through an umbrella with the head zoomed to 24mm. At 24mm the GN drops to 92 feet (28 meters). The Guide Number (GN) is a standard measurement serving to indicate a flash unit's output by calculating the distance times the f-stop, with respect to the film speed. The guide number relates the film speed to the actual flash output. A Guide Number is determined by placing the flash unit at a desired distance from the subject (usually 10-feet), and metering with an accurate flash meter. The guide number can be calculated from the distance and the f/stop (GN = f/number x flash-to-subject distance). 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…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. These output readings have been measured with a Gossen Ultra Pro Flashmeter (ISO 100), placed 10-feet from the flashtube for direct reflector specs. The readings represent the output of each unit at its full power setting. Readings were taken in the center of a 20-foot x 27-foot white room, with 20-foot ceilings. Please note that readings may vary when taken in other environments and with other meters, as different brands of flashmeters can vary in their interpretation of correct values. The stated maximum Guide Numbers (GN) were calculated by multiplying the distance (10 feet) times the measured output in f-stops. Mike Sowsun / SL1 / 80D / EF-S 24mm STM / EF-S 10-18mm STM / EF-S 18-55mm STM / EF-S 15-85mm USM / EF-S 55-250mm STM / 5D3 / Samyang 14mm 2.8 / EF 40mm 2.8 STM / EF 50mm 1.4 USM / EF 100mm 2.0 USM / EF 100mm 2.8 USM Macro / EF 24-105mm IS / EF 70-200mm 2.8L IS Mk II / EF 100-400 II / EF 1.4x II
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ElectricDreams Member  76 posts Likes: 1 Joined Jun 2010 More info | Mar 20, 2011 22:14 | #3 #1 - The 580 works off AA batteries, unless you have an AC adapter. The AB800 is AC only. If you are shooting on location like a beach, alley in the city, or open field the 580EX II will probably be better since you won't need to lug around a power pack. Electric Dreams Inc
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Mar 20, 2011 22:25 | #4 Thanks guys. I was thinking about making a DIY beauty dish for it since I can connect it to my 7D wireless. Its kind of off topic but is there any way I can use the 580 and 285HV together. I put myself in a bad spot because I have a box of cactus v4's that I bought for the 285HV and after buying the 580 I realized im going to have to buy another v4 trigger since the 7D in camera flash has to be popped up in order for me to wirelessly connect to the 580 preventing me from putting the v'4 receiver on my camera hot shoe for to trigger the 285HV. Screwed myself
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Wilt Reader's Digest Condensed version of War and Peace [POTN Vol 1]  More info | Mar 20, 2011 22:28 | #5 The manufacturer's claims for Guide Number for many different brands have been substantiated by several POTN members to be optimistic by about 1EV...Canon, Metz, Sigma ETTL compatible flashes all seem similarly optimistic. In another recent thread in which I posted, where my own Metz 54MZ flash was supposed to reach 14' at f/8, it really only could reach 10' at f/8 as measured by a Minolta flash meter, for example. So MSowsun's comparison of 580EX vs. AB800 overstates the 580EX power because he used Canon claims for GN, truth be told! You need to give me OK to edit your image and repost! Keep POTN alive and well with member support https://photography-on-the.net/forum/donate.php
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CxThree Senior Member 713 posts Joined May 2009 More info | Mar 20, 2011 22:43 | #6 Watch this. Mark does a good job of showing you the differences between speedlites and strobes. Not the specific models you asked about, but the info is probably going to be useful to you as you learn off camera flash. Canon EOS 5D MKIII, 7D
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Mar 20, 2011 23:25 | #7 CxThree wrote in post #12059749  Watch this. Mark does a good job of showing you the differences between speedlites and strobes. Not the specific models you asked about, but the info is probably going to be useful to you as you learn off camera flash. http://www.youtube.com …ramaTV#p/u/11/s0ZmscWEc1c great vid...thanks
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yogestee "my posts can be a little colourful"  More info | One huge advantage studio flashes have over Speedlites is modelling lights.. These take the guess work out of flash placement and lighting ratios.. Jurgen
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Wilt Reader's Digest Condensed version of War and Peace [POTN Vol 1] More info | Mar 21, 2011 10:49 | #9 Yogestee, I think it is important to point out to the lighting newbies flocking out there, that you are a veteran in lighting who can set lights now without benefit of modelling lights, but it took a learning period WITH the modelling lights to learn how to set the lights well, later without modelling lights. You need to give me OK to edit your image and repost! Keep POTN alive and well with member support https://photography-on-the.net/forum/donate.php
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BrandonSi Nevermind.. I'm silly.  More info | Mar 21, 2011 12:21 | #10 ElectricDreams wrote in post #12059572 #3- The AB800 will also recycle faster than the 580EX, power output is relatively the same with the AB800 being a little brighter at full power. This is crazy talk. A B800 is in a different league all together concerning output. Maybe if you put 2-3 580EX's together, you might be close.
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Mar 21, 2011 12:33 | #11 BrandonSi wrote in post #12062815 This is crazy talk. A B800 is in a different league all together concerning output. Maybe if you put 2-3 580EX's together, you might be close. ahhh...thanks
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Wilt Reader's Digest Condensed version of War and Peace [POTN Vol 1] More info | Mar 21, 2011 12:48 | #12 So if the 580EX at 24mm coverage is really GN66, not Canon's overstated GN92, and if the AB800 is truly GN172, then we can estimate that one AB800 is equivalent to about seven 580EX flash units. You need to give me OK to edit your image and repost! Keep POTN alive and well with member support https://photography-on-the.net/forum/donate.php
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