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Author Topic: Camera Scan Lighting  (Read 2748 times)
jcbenner
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« on: January 05, 2010, 07:29:31 PM »


For my own work, I use one with the diffuser removed. I don't want a piece of dust to show up in a lot of images.

It does mean that you need to make sure the light is well-diffused.  I've found the need to triple-diffuse my strobes - A softbox with a baffle, and then a piece of milk plexiglass between the softbox and the film stage a foot or so back).


Hi Peter,
 
I have a few questions about you lighting.  I have found the lighting set up to be very critical in terms of getting accurate colors, and I wanted to see what exactly you were using? How many watt-seconds?, what size softbox?, set-up how far away?, etc.  Any chance you have a photo of your lighting set up?

Thanks!

John
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peterkrogh
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« Reply #1 on: January 05, 2010, 07:40:13 PM »

John,
LIghtbox color should not be critical for accuracy, as long as it is a basic daylight (tungsten is too far to the red part of the camera's sensor sensitivity zone).
I use an 18x24 inch chimera on a Balcar head connected to a Luz pack (any old-timers remember these great packs?). The pack is 800 ws, and I set it up to shoot around f/8 (test your lens for best combination of sharpness and DOF).

Typically, the head is about 18 inches from the film, and I use a second diffuser made of milk plexiglass between the film and the lightbox.

No good photos handy at the moment, sorry.
Peter

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jcbenner
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« Reply #2 on: January 05, 2010, 08:08:09 PM »

Thanks for the reply.

 The color sensitivity I was referring to relates to how diffuse the light is.  More diffuse light seems to give better color accuracy.  I am going to invest in a decent flash head for this work, and was interested in what others are using.

Thanks again.

John
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peterkrogh
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« Reply #3 on: January 05, 2010, 08:36:40 PM »

John,
I agree that diffusion is a good quality in a light source for this.  I printed on a diffusion enlarger, and it minimized the film artifacts.

One issue is that light-head modification is generally about making an even spread of the light, as it spreads out *from* the light head.  That is pretty different from making light evenly diffused as you point the camera *toward* the light source.  The former can be accomplished with one or two levels of diffusion, and the latter wants two or three levels.

To be more precise, the softbox I use has an internal baffle, so the light is actually diffused three times. twice through fabric (which does not do a complete diffusion) and once through Plexiglass (which does).

Peter

Peter
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jcbenner
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« Reply #4 on: January 08, 2010, 08:25:03 AM »

Peter,

In your experience, would you expect that a 640 W/s unit (Alien Bees B1600) would have enough power for a softbox + baffle + plexiglass triple diffused lighting set-up? With your 800 W/s unit are you in the middle of the power range or near the high end?

Thanks,

John
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peterkrogh
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« Reply #5 on: January 08, 2010, 11:53:33 AM »

John,
Typically, I found I had to turn the flash way down. I'm sure 640 w/s is plenty.
Peter
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