Expo Disc White Balance Aid

N

NASACAM

Member
http://www.expoimaging.com/product-...Disc_Neutral&gclid=CJmR1Z_z06cCFZFoKgodciSg_A

I'm not sure if this has been discussed here,,but it is new to me. I'm shooting this week in some simulators here at JSC. One dome called the Alpha Dome has a mix of projectors relecting a seamless huge image on a dome. I was worried about white balance when a photographer handed me this funky round disc. It basically is a very cool white balance aid that he has been using in lieu of a gray or white card. All you do is hold it in front of the lense, point the camera at your main lighting source and white balance.

You guys probably already know more about this but I thought I would share anyway.

And maybe get back to the basic fun of shooting.!!!
 
The usual places. BH Photo Video, Amazon, Adorama. The cost betweej $75 and $100.00 And you really don't need to have an exact match on thread size as long as it covers the lense. I would do with a 77mm because it covers most lenses. Again, you don't need to attach it, just hold it over the lense.
 
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I've seen these used for stills, but haven't seen their results with video. Now I'm curious, especially for very mixed CT.
 
A friend got to play with one for some stills under a whole mixture of light... it was at night under a freeway overpass, so a mix of mercury vapor, sodium vapor, and I think some incandescent. The results he showed me were spectacular. They do make a video version... it's slightly larger, NASACAM is right, any size will work so long as it covers the lens.
 
I've got both the 72mm neutral and warm Expodisc versions for my Canon A1s. The neutral really works in mixed colours, fast and accurate. If you buy a large one to cover all your lens, make sure it'll fit inside your lens hoods. There are threads here back in the archives somewhere.

There's Eastern versions on Ebay and buyers complaining those are not worth anything. HTH.

Cheers.
 
Raster, can you put it on your lens and simply point at your subjects, or do you need to aim at the primary light source like they recommend?
 
Mike, I frame the shot, put the Expodisc on the lens, it clips on, and do a custom white balance. That takes care of the WB even tho I might zoom in for a closer take, but if I move the camera and reframe the shot I do another CWB, it only takes a few seconds and saves work in post.

The Expodisc case has a loop you can tie on your belt and I've found the more you use it, the better you get at knowing when you need to run it. For mixed lighting, say sunlight coming in on a biege wall, there's no contest. I'd get the neutral version, I use my warm one for head shots. HTH.

Cheers.
 
It seems ExpoDisc works like an incident filter so it has an adavantage for your camera by reading incident light vs. relying on a reflective surface on a white card or t-shirt as many of us used as WB reference in a pinch. I balanced to a projector in this case that was closest to me and it worked great. It depends on what you want as reference WB for your look. I ordered one last night from B&H for $99 since Mike (the photog) took his back. :)
 
I'll get one... I occasionally use a small cutting of Roscoe tuffspun over my matte box to do the same thing, but it looks as if this thing focuses the light, which is great, similar to the lens on a Spectra meter that turns it into a reflective. Problem with matte box, probably, but hopefully the largest one will work without having to swing it out.
 
One item of note, as I'm an Expo Disc user, is to read the manual. Expo Disc recommends different white balancing technique than we're used to with a white or grey card. Think of using it like a light-meter. From the documentation:

4. AIM THE CAMERA (MEASURE INCIDENT LIGHT). Use the ExpoDisc as an incident tool. Position the camera so that the light source illuminating your subject passes through the ExpoDisc, usually by standing at your subject’s position and pointing the camera back towards where you will be taking the shot.
Click to expand...
Good shooting folks!
 
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