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Old January 7th, 2007, 05:46 PM   #1
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White foam core that is spectrally-neutral ?

Hi,

Can anyone recommend a source for spectrally-neutral foamcore. I'm trying to cover a few 5' x 5' patches olive green ceiling areas with a decent reflective material.
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Old January 8th, 2007, 06:07 PM   #2
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I've been buying formcore for reflecting lights into camera lenses for about 20 years now, and all I've ever done is go to the local ART SUPPLY store and buy what they have on hand. (You may have trouble finding larger than 4x4 tho, which is a typical half sheet of 4x8 stock.)

I don't think I've EVER seen foam core reflected light on a scene that looked significantly different from the source hitting it.

I gotta admit tho, I've never tried to isolate the reflected light on a 'scope to judge it that critically.

There's another thread here about ceiling colors. You sure you want white? Yeah, it will increase overall light levels on your screen. But it also can reflect specular highlights off anything reflective and curved on your set.

That's why my studio ceiling is flat black. Ugly as hell, but you never see it in a reflection - YMMV.
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Old January 8th, 2007, 07:53 PM   #3
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Bill,

Just curious what thickness do you get?

Bill
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Old January 8th, 2007, 07:55 PM   #4
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What Bill says. Foamcore is pretty darn neutral. Many types of bounces are less so, like beadboard and muslin, which impart a warm tone (may be desirable under certain circumstances).
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Old January 9th, 2007, 01:59 AM   #5
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Thanks, guys. I bought some white foam core boards from Office Max that were about 3' x 3' and I ended up actually needing less material than I previously thought as the additional coverage didn't change light levels that much. Basically, I was just looking for a cheap way to increase light levels outside my home without increasing the wattage. I videotape martial arts, and sometimes I need some shots of the guys getting sick or recovering outside. The foam core really helped with bouncing the light without making my home exterior into a permanent lighting set.

Bill, that's a good point about white ceilings and specular highlights. You've alerted me to be prepared for any problems.
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Old January 9th, 2007, 02:25 AM   #6
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The joys of foam core.

Bill,

I think it's around .25 inch. It seems to be the standard weight at art supply houses. I think there's thicker, but I don't bother with it. It's a semi-consumable the way I see it. If it lasts a year, excellent. If it lasts a shoot - such is live. I love that my art supply store carries three types - white both sides, black both sides, and the really cool and black/white.

The best thing about quality foamcore is that if you score it with a matte knife about halfway through, it "breaks" cleanly and the paper backing stays attached. So you can build lots of useful stuff with it.

In fact, the lid of my larger Pelican case holds my "emergency" reflector. It's a piece of black/white scored in thirds. Pop it open and you have a nice big bounce fill, or cutter.

I also find lots of uses for the black.

In fact...

About four years ago, a CEO I work with decided to do a "retro" presentation and had the AV company set up an OVERHEAD projector with transparencies! (Hadn't seen one in years!)

Nothing like a dark room, 9 million watts of light shining straight up on the CEO's chin making him look like Dracula. PLUS the "open table" light source meant that everytime the camera had a shot of the overhead projector, a HUGE light smear appeared.

Drove me nuts until I took a piece of black foamcore - cut it into a 3 sided box and gaffed to the table so that it surrounded and stuck up about six inches taller than the bed of the overhead and BINGO, no more light smear!

God bless foam core.
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