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05/15/2009 06:35:49 AM · #1 |
| I am looking at getting 2 Alien Bee B400 monolights. At 160 True WS and 400 effective WS using shoot through umbrellas roughly how far away could I set them at 1/1 for portraiture. Camera set at ISO 200 @ f8. Then same question using white reflective umbrellas. |
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05/15/2009 07:49:42 AM · #2 |
it's not a distance thing at all. often closer is better for a soft light look.
what you'll have with lower wattage lights is less light - meaning smaller groups of people (like 1 or 2 at most) and a harder time overpower ambient light (so the studio will need to be fairly dark), and you'll shoot more at 5.6 than 11.
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05/15/2009 07:59:15 AM · #3 |
| Sort of the opposite answer of what you're asking:I have two AB 400s and, in my tiny studio, I find that I often need to attach neutral density filters to tone down even the lowest setting, since I like to put the lights close to the subject. Sorry I can't say how far away they can be! |
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05/15/2009 01:00:32 PM · #4 |
| Thanks for the replies. I just did our taxes (auto extension because I am overseas) and it looks like I might be able to go for the B800's!! |
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05/15/2009 01:07:04 PM · #5 |
Originally posted by david1707:
Thanks for the replies. I just did our taxes (auto extension because I am overseas) and it looks like I might be able to go for the B800's!! |
I have 300ws strobes, same output as the AB800, and I don't really ever need more power, even with large softboxes.
So go for the 800s (even if you have to skip dinner a few nights)
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05/15/2009 01:25:35 PM · #6 |
I agree--I get to use these regularly at a local studio, and the AB800's are the best choice. The 1600s are just too powerful for indoor portraits. You could get along fine with one 800 and one 400 if you want to save a few dollars.
And, yes, getting close at low power is beautiful portrait light (thru a softbox or shoot thru umbrella). If you get a convertible umbrella for one, and grid for the other's funnel reflector, you can do some cool stuff. |
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05/15/2009 02:20:42 PM · #7 |
Actually calculating the distance is fairly easy if you know the guide number. The calculations is guide number/f-stop=Distance.
So for the AB400 the Guide Number is 118, for the AB800 the Guide Number is 172. Keep in mind, Guide Numbers are rated at ISO 100, so if you wanted to shoot at ISO 200 you will need to move the flash further away.
But for your example (these numbers are for the 7" reflector which is rated very similar to the reflective umbrella):
AB400 - 118/8= 14.75 ft.
AB800 - 172/8= 21.5 ft.
For a shoot through umbrella you loose approximately a stop so even though you're still shooting at f/8 you would want to use f/11 as your f-stop in the calc.
AB400 - 118/11= 10.7 ft.
AB800 - 172/11= 15.6 ft.
Alien Bee specs can be found here:
AB Specs
Kind of confusing but hopefully this helps. |
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05/15/2009 02:42:16 PM · #8 |
| Those numbers are very helpful. In the large studio nearby that I get to use, though, we seldom run the 800's at full power (so you don't need to have 21.5 ft of linear distance in your garage/studio, because you can dial down the 800 and move in closer--and you get better portraits when you do :-) |
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05/15/2009 03:23:06 PM · #9 |
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05/17/2009 03:14:36 AM · #10 |
| Thanks for all the great replies. I now have authorization from Household 6 to get a kit with 2 B800's plus Cybersyncs to go with them!! I lost an opportunity to shoot the portraits at a Battalion's Ball coming up because I just didn't feel my Vivitars off camera through umbrellas would cut it. Last thing I want at something like that is to have to change batteries mid way through or to not have enough light to overcome the ambient. That won't happen again. |
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05/17/2009 08:20:28 AM · #11 |
| Just guessing why you're asking, but a light meter really is something you should consider. |
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