Gary,
I've made the same type of Math error. My saving grace was shooting the same speed polaroid as sheet film. So I was able to see my error in my initial test shots the day of the shoot. It sounds like you have a good set of strobes.
Good luck,
Mike Davis
The only time you worry about shutter speed with flashes/strobes is when you want to balance existing light. But if you are only using the strobes then you basically set the shutter speed fast enough and ignore it.
Unless you increased the shutter speed past the speed of the strobes you should have gotten something. The thing is no LF lens has a shutter so fast it can't handle your lights.
On the Speedotron website you can download the current manual.
800ws is pretty power full at six feet.
You can gel the lights to lower power. You can move them further away. So you don't need to change either F/stop or shutter speed.
I have a feeling that this is a metering issue.
As your 'blad and your large-format lenses are leaf shutters, we don't need to worry about shutter speed.
You also don't need to worry about flash duration, it's fine, it takes care of itself. It will always be faster than your fastest shutter speed on a leaf shutter.
With a flash meter that shows lighting ratio (ambient -v- flash) it's easy to see what the break point shutter speed is. That is the point at where you start to drag the shutter and allow ambient light to start illuminating your background. Usually speeds slower than 1/60th will allow ambient light to have an affect.
So I would re-read the manual on your Polaris and understand how it behaves. This weekend I was helping my gf on a baby shoot. I set up my power pack to give out enough juice to correctly expose at 100iso, f8 at 1/125th (as metered by my trusty Minolta V).
Once you figured out the metering and maybe always stick to one film, you'll be good.
The metering could be a part of it. I've been searching for the manual for a week. It's somewhere...
I don't have my strobes with me to test, but 800ws, direct with no diffusion, at 6 feet should be pretty close to f11 on ISO 25 film. Maybe 1 stop under, but should have exposed something if shutter was fired correctly and the dark slide was pulled.
Ya I'm having the same problem. I can't imagine a metering problem that would lead to totally blank film. Over exposed maybe.
If you metered the modeling lights instead of the strobe then you would have over exposed most likely.
He said it was 800ws of bounced light at 6 feet.Originally Posted by gregstidham
I don't have my strobes with me to test, but 800ws, direct with no diffusion, at 6 feet should be pretty close to f11 on ISO 25 film. Maybe 1 stop under, but should have exposed something if shutter was fired correctly and the dark slide was pulled.
There is no way that 800ws of bounce at 6ft would overexpose PL25 at f11.
No I was thinking of the other films that also ended up blank. How did they all end up blank?
Well, we know that the 200 and the 400 had images when pushed. This makes me think that everything else was under exposed. I don't know by how much. But I do know that if you start trying to use shutter speed to control lighting with the flash, you are going to have trouble.
That can be a tricky realization sometimes. Those of us who shoot mostly natural or hot lights are used to using a combination of shutter speed and aperture to control the lighting and dof. With the flash, a slower shutter won't double the amount of light as it would with hot lights.
Mike
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