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Old July 19th, 2013, 05:24 AM   #1
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Any advantage to grey target instead of white for white balance?

In the old days we used 18% grey cards because they doubled as incident light meters with film cameras, but nowadays using white targets seems to be the norm; there is nothing special about 18% if you are not going to be using the card for metering.

So this brings up the question: Is there an advantage to using a 18" grey target these days, to calibrate a video camera?

I would think the white might be better since the camera gets a stronger signal, and video cameras seem to be designed for white targets.

But then again I suspect that a white target may tend to clip the sensor during calibration more than an 18% grey target would. Electronic things tend to be most accurate in the middle of their gain ranges. If cameras don't adjust their exposure while doing a white balance, then a grey card would simulate skin tones better than a white card.

The practical question is whether it actually makes sense for me to buy a lastolite ezybalance target with the 18% grey, or whether a lastolite triflip white would work just as well. I suppose it's likely the white of the ezybalance is more exactly white than the triflip white.
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Old July 19th, 2013, 04:48 PM   #2
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Re: Any advantage to grey target instead of white for white balance?

Tom, I think you covered the issues in your question.

At a Canon-sponsored event a few years ago, they said the same: Use a white card rather than gray for the stronger signal, lower nose, and more accurate white balance. But don't clip. Move the card so it's not as bright or temporarily lower the exposure of the camera if needed to custom white balance without clipping.
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Old July 19th, 2013, 05:27 PM   #3
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Re: Any advantage to grey target instead of white for white balance?

Tom,This comes up a lot. It's a real chicken or the egg conversation all the time.

I have the Lastolite that is white on one side and 18% gray on the other.

I find myself using the white side for white balance and the gray side for exposure..

That probably doesn't clear things up, but I hope you're not confused at a higher level.:)
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Old July 21st, 2013, 06:33 AM   #4
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Re: Any advantage to grey target instead of white for white balance?

John, that's good advice: Essentially get as high as you can before you close to nonlinearity (clipping).

I'm not enough of a camera guy to know so perhaps someone can tell me: is a matte white piece of card material at subject position typically in clipping or not? Do zebras typically appear in white balance mode?

I'm wondering if grey is safer for novice camera ops that might end up not noticing clipping during whibal, while white is better for people who know what they are doing.

I suppose this could be a reason that some people angle the grey card downards... if angling it towards the light overexposes that could be why they find it effective to angle away.
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Old July 21st, 2013, 11:58 AM   #5
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Re: Any advantage to grey target instead of white for white balance?

Quote:
Originally Posted by Tom Morrow View Post
...is a matte white piece of card material at subject position typically in clipping or not? Do zebras typically appear in white balance mode?

I'm wondering if grey is safer for novice camera ops...
Quote:
Originally Posted by Jon Fairhurst View Post
But don't clip... temporarily lower the exposure of the camera if needed to custom white balance without clipping.
Jon's guidance on temporarily changing exposure to bring the white target below clipping is simple and effective. Even a novice should learn this level of control!

For Zebras to possibly show in the way you suggest, they would need to be turned on, and set at 100%. Whether they would show on the target depends on illumination and exposure, there are correctly exposed scenes with no true white at 100% or above. An experienced cam op should be well familiar with this... but may likely have zebras set at 75 to 85%, which is a handy range for exposing to the highlights on caucasian faces.

IMO a "novice" cam op needs education & practice with industry standards, such as balancing to a white target. Conforming to this standard is going to serve you and serve them best; an experienced op on one of your shoots will find familiar procedures, and your novices will be learning skills that they can use anywhere.

Maybe you're not concerned about that last one... but there is a cost to being an island of non-conformity, in constantly explaining to people "no, we do it this way here." And there will be some who are balancing to white, not grey, no matter what you do! Do your projects depend on a wider community of pros?
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Old July 26th, 2013, 02:22 AM   #6
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Re: Any advantage to grey target instead of white for white balance?

I've seen a number of methods used for setting the white balance exposure with white target, some people switch to auto exposure, some just use the zebra levels (70% or whatever), others just do it eye, so it's not clipping. They all seem to work in practise.

Just to throw in a wild card, I've seen people do a white balance by using a wide shot of the room. Surprising, it does work for many locations, although.you'd need to be careful of extreme colours, It tends to get used following fast action on documentaries.
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