B800s to much? Help with SB vs shoot through

Just got three B800 a few weeks ago and things are starting to rock and roll with my other gear and I am ready to start test shooting. Here is my problem, well one of my problems, I have a huge octabox 63" and my first few test shoots I flashed two b800 onto solid white background, used my kids as subjects, and here is what I got. With both B800 on BG I had to turn them all the way down to get an F10 on my Light meter next the soft box was at 45 angle and about 4 feet away turned all way down and it was giving me f9 on side of my sons face at ISO 160 SS of 250. Well his face was blown out and the BG was too. I want the BG blowed out a bit so that wasn’t too bad But some of it was bouncing back on to him. I ended up shooting at f10 and f11 and they looked better but not great.
My question is, why did the large soft box and the B800 turned down still give me an f9 on my subject? Did I buy too much light or am I doing something wrong? Does the soft box need to be a lot further away? I do not have much room for testing right now but I can assume that is my only option for now. Would a shoot through umbrella do better or maybe a bounce back one?
Thanks for your help.

Well, one way to compensate is to move back the light about 40% more than what it is. That'll bring you down about a stop.

Does your octabox have a diffuser panel that you're able to put inside the softbox? That'd lose up to another stop of light, and soften it even further.

The B800s are powerful little guys, so I wouldnt be so suprised if 3 is too much for a small studio, but I use 3 quite a bit, and never feel like I have way too much light

Why you shooting at ISO160?

In my quick tests with my photoflex 5' octodome, I get f8 at ISO100 at a distance of 8 feet with AB800 at 1/2 power. I have both internal and outside diffusion panels installed.

Using AB800 with a medium SB, I get f2.8 with power at lowest setting with subject at a distance of 4-5 feet.

BigAlz-

Something is not right there. Dont forget to fire your strobe after you change the power setting to clear the capacitor. There is no good reason to use anything else in studio besides ISO100. Bobbz power measurements are consitent with my AB800s. What brand of SBs do you use?

-Scott

With B400 at somewhere in the middle between 1/4 and 1/2 power, I'm getting ISO100, f/8, with the large (3x4') softbox around 3-4 feet from the subject. Does that sound reasonable for your purposes?

Kristic wrote in post #7561537
Well, one way to compensate is to move back the light about 40% more than what it is. That'll bring you down about a stop.

Does your octabox have a diffuser panel that you're able to put inside the softbox? That'd lose up to another stop of light, and soften it even further.

The B800s are powerful little guys, so I wouldnt be so suprised if 3 is too much for a small studio, but I use 3 quite a bit, and never feel like I have way too much light

Kristic... are these really that powerful? i was thinking of upgrading them from 285hv. i want to have a stand fight against the sun in mid daylight.

Marloon wrote in post #7563216
Kristic... are these really that powerful? i was thinking of upgrading them from 285hv. i want to have a stand fight against the sun in mid daylight.

Are they powerful? Absolutely, they're studio strobes. But lets keep this all in mind:

Alien Bee B800 - 800 Watts
Sun - 386000000000000000 Watts

:p

Kristic wrote in post #7563229
Are they powerful? Absolutely, they're studio strobes. But lets keep this all in mind:

Alien Bee B800 - 800 Watts
Sun - 386000000000000000 Watts

:p

thanks for the quick reply. how much Ws does a normal strobe have? thats what i've been trying to find out, but i cant find an answer.

Well, I can tell you that the B800 is over twice as powerful as a 580EX. As for actual wattage, I couldnt tell you

Depending on how you like to shoot, the 800's can be waaaay too much power.

I like to shoot 2.8 to 5.6 with my lights in close, and I am always working with the lights turned all the way down. At ISO 50. This can certainly limit your creative choices.

What's more, you will get unpredictable flashes at the lowest power settings on the AB's. Meaning the actual power and color of the light will vary from shot to shot. Not good!

Buying more power than you need is bad advice, yet I see people say it all the time!

Here is an old thread about exactly this -

https://photography-on-the.net/forum/showthre​ad.php?t=456455

580ex is ~80ws. AB800 is 320ws, or ~two stops brighter.

suyenfung wrote in post #7563433
580ex is ~80ws. AB800 is 320ws, or ~two stops brighter.

thanks. can i also assume that my vivitar 285hvs are more or less 80ws as well? ALSO... after buying 285hvs, i've been put off the idea of buying more canon flashes. i HATE ETTL flash, because it has become so unpredictable to me after i've learned how to manually control my lights. also... during small events, i put up 285hvs in the corners of the room and have a perfectly lit event.

WOW thanks guys for the replies, and as for the 160 ISO, according to all the tech data I have read here and other places, it actually has less noise then ISO 100 do to the digital algorithms. It is true for 320 over 250 and 640 over 500. But only those three, the rest of the 40D ISO range fall in order in noise.
Here is a chart listing noise levels from lowest to highest on the 40D.
ISO 160
ISO 100
ISO 200
ISO 320
ISO 125
ISO 250
ISO 400
ISO 640
ISO 500
ISO 800
ISO 1000
ISO 1250
ISO 1600
ISO 3200

Note how poorly ISO 125 does. Here is some more info for you guys on this matter.
http://forums.canonpho​togroup.com/showthread​.php?p=5225

Time to go shoot with my new toy, 70-200L 2.8 IS. My first real lens.
Again thanks for your input

You cant measure WS of hotshoe flashes against studio lights. Unless you have one of the good sunpaks from back in the day, they are not a bare bulb. You are comparing an internal reflector in the hotshoe flash vs what in the studio flash? Bare bulb? Umbrella? 80 degree reflector? 40 degree reflector? What zoom setting is the hotshoe flash? 28mm? 105mm?

Too many reflector variables to figure how much actual light you get out of each one compared to the other.

BigAlz1 wrote in post #7565089
WOW thanks guys for the replies, and as for the 160 ISO, according to all the tech data I have read here and other places, it actually has less noise then ISO 100 do to the digital algorithms. It is true for 320 over 250 and 640 over 500. But only those three, the rest of the 40D ISO range fall in order in noise.
Here is a chart listing noise levels from lowest to highest on the 40D.
ISO 160
ISO 100
ISO 200
ISO 320
ISO 125
ISO 250
ISO 400
ISO 640
ISO 500
ISO 800
ISO 1000
ISO 1250
ISO 1600
ISO 3200

Note how poorly ISO 125 does. Here is some more info for you guys on this matter.
http://forums.canonpho​togroup.com/showthread​.php?p=5225

Time to go shoot with my new toy, 70-200L 2.8 IS. My first real lens.
Again thanks for your input

You not going to find any noise difference between ISO160 and ISO100 and that too in a studio environment.