White Balance Question(s)
 

Hi All
I'm in the process of shooting copies of my super 8 productions of many moons ago. All is working well--the projector and PDX-10 work together well, and I get no flicker. Shooting at 1/30, and have a variable speed control on the projector that helps, too.

The problem I have is with the white balancing, and I'd like some opinions/help. Here's my set-up:

I have a pure white matte foamcore board on the wall as a screen. When I turn on the projector (without film running through it) and use the light of the projector's beam to get a manual white balance, the overall cast to the resulting video image is a slight, but definite, greenish. When I switch to either the tungsten or daylight settings, they are VERY blue and yellowish, as I guess I would expect, so the manual setting is much closer to "real". But the image of the projected film is quite warm, and the manual white balance renders them considerably colder than their true colors. Much greener.

Is there any way to adjust the white balance so that it is completely neutral, and lets me record without negating that warmth I am seeing? Some way to "trick" it? Any tips?

I of course can correct this in post, but I'd like to get it as close to correct before I resort to doctoring..

Thanks for any ideas you might have.

As someone who designs scenery and lighting, then films them with both video and still cameras, I can tell you that white balance is a compromise at best. It gets really frustrating; you simply can't accurately capture the same colors that your eye sees. Just setting the white balance to the raw color of the lamp will get you sort of into the ballpark, but there will be problems with rendering all the colors correctly. I really see this driven home in our current production. We have singers and scenery lit with halogen stage lights in front of a big screen with 40' wide DV projections. The projectors have Xenon lamps. So if I white balance for the stage lighting all the projections look too blue. There is really no solution to such a dilemma.

I think you just need to do some trial and error to find the best compromise... or at least that's my approach. You don't mention setting the WB shift in the custom presets; have your tried that? After white balancing you can "warm it up" by shifting the white balance. You might also want to either saturate or desaturate the colors using the "color lvl" custom preset.

How about gels and filters?
 

> We have singers and scenery lit with halogen stage lights in front
> of a big screen with 40' wide DV projections. The projectors have
> Xenon lamps. So if I white balance for the stage lighting all the
> projections look too blue. There is really no solution

Have you not tried gels for the halogens and/or filters for the xenon projectors?

Thanks, Boyd.
What you describe is very similar, indeed! And it sounds like a real problem. It's frustrating to see something's true color and not be able to coax the equipment into "seeing" it the same way.

I've gone back and tinkered some more, and one interesting thing is that there is a subtle halo effect in the color of the raw beam. In other words, when I WB using the beam, the center of the framed beam is whitest, gradually falling off into an ever-deepening greenish color--this effect is more apparent when the WB setting is more heavy-handed, like the presets for tungten and daylight. I assume it's the different color temperature of the bulb's output, varied either by it's design or age or by whatever diffusion lens the projector has to even out the light. I changed to a new bulb, and while it's better, it's still there. None of this effect is really visible to my naked eye, but the camera sure sees it!

You mention something that I have not played with at all--the custom presets. I just haven't gotten around to that area of the camera yet! It sounds like that is where I will find my best compromise. I'll go in there and play with the WB shift.

That's precisely the type of info I was looking for! Something that I might not have thought of, since I haven't spent any time with it (yet!). So thanks again.

By the way, Boyd--I love the design stuff on your site. Just beautiful. I'd love to see a production or two some day. Maybe next season! I'm down here near Frederick, Maryland, so it's not too far of a drive at all.

Try doing a manual WB while projecting the film. It may take several attempts to get satisfactory results.

Re: How about gels and filters?
 

<<<-- Originally posted by Ignacio Rodriguez : Have you not tried gels for the halogens and/or filters for the xenon projectors? -->>>

Well of course the stage lights (there are about 400 of them) have a variety of gels, some of them with color scrollers even. But not really sure what you mean here. We do shows for live audiences, not for video. The video is just for our archival purposes so it wouldn't make sense to try to re-light the show or change the projections to suit the shortcomings of DV. The challenge is finding the best combination of camera settings and post color correction. Even so, it's a poor facsimile of the original. I've learned that most of the effects which we really like on stage involve a contrast range way beyond what video, or even film, can handle.

But even so, I like the video coming out of the PDX-10. I would not want to go back to the VX-2000 for stage use.

<<<-- Originally posted by Chris Long : the center of the framed beam is whitest, gradually falling off into an ever-deepening greenish color -->>>

Sounds like this is caused by the condensing lens/reflector in the projector. You could try using the custom preset WB shift and color lvl to make the greenish part more neutral. Also, have you experimented with different exposure settings? This can make a big difference as well.

Thanks for the nice words Chris!

If you are not able to adjust the presets within the camera to where you like it, you can try tricking the white balance by holding gel in front of the lens while setting the balance. For a greenish cast, use a Minusgreen (magenta) gel. The best weapon is the Jungle Book (available through Rosco. It will take some trial and error but eventually you can find a filter pack that will deliver the right white balance for true color rendition. Very useful for regular shooting as well.

Yes, white balance, focus and flicker are the film transfer problems I come up against. I do a lot of film to video transfer and I've had to accept that I'll do a lot of colour correction in post. The other two must be right at the start. With the Canopus Storm colour correction is instant and therefore very gratifying to do, but even with different rolls of Kodachrome 40, there's always improvements that can be made in post.

tom.