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Old Mar 21, 2005, 9:34 AM   #1
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Hi, I am reading all the time that people set a custom white balance before shooting a important shot.

I am relatively new to Digital and I am discovering new techniques all the time, however I read my manual and shot a couple of frames,


Canon 20D; SS, 1/20 sec; EP, Normal Program; F/5.6; ISO, 200; FL, 55.0m; Auto White Balance; Meter Mode, Pattern.


Canon 20D; SS, 1/20 sec; EP, Normal Program; F/5.6; ISO, 200; FL, 55.0m; Custom White Balance; Meter Mode, Pattern.

I do not know about you, but I can not see much difference? So when is the optimum time to shot with Custom White Balance. Would it make a difference with flash? I was kind of expecting the background to be, well white!

Any hits or tips will be grateful received.

Thanks

Grant
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Old Mar 21, 2005, 10:53 AM   #2
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Custom white balance is not often needed, but it can be helpful.

This is how I would think its used, but the way I shoot I can't use it.

If you have different light sources, each with their own color cast, then a custom white balance is often helpful to let you correct for them. Take a picture of something white under that lighting and then use that to set the balance... and it will correct for the color cast.

But it is only useful if the lighting will be constant through the entire shoot. Since I shoot outdoors I can't use it.

If you are using a flash, then the camera already has a white balance that can bet set for that.

Eric
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Old Mar 21, 2005, 1:27 PM   #3
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Eric is right on. I use auto WB outside with very good results. The only time I set a custom WB is inside where lighing is non-white. A perfect example is a gymnasium. Whatever the bulb type most of them use, they often seem to give off a yellow or orange cast. In that case it is good to use custom WB (or just shoot RAW). But, be careful - you need to take your 'mapping shot' under the light your photo will take place under - which may be different than where you are seated. An example is an auditorium / stage. The lighting at your seat is likely different than the lighting on the stage, so using a white/grey card from your seat will not give you desired results for shooting someone on stage. In that instance, if you can't get to the stage to record 'mapping shot' then your best bet is to shoot RAW and set WB then.
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Old Mar 21, 2005, 1:44 PM   #4
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Sorry, whats a 'mapping shot'?
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Old Mar 21, 2005, 3:34 PM   #5
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The mapping shot is a shot of a white or grey card used to set the custom white balance. When using custom WB you must set it under the lighting you intend to shoot under so you have to reset it for each shoot.
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Old Mar 21, 2005, 3:54 PM   #6
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Oh I see, yeah I know how to set the custom white balance, I just did not understand the terminology :sad:
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Old Mar 21, 2005, 4:54 PM   #7
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Hi,

I was having the same concern as Grant. I have 2 optional present buttons for custom WB in my Toshiba digicam that I never usedsince I'm not sure what they're for. The manual says they're for custom WB but I don't know what it means until I read this post. However, I still have aquestionabout setting the custom WB.

To set it,all of you said to take a picture of something white under the lighting where we're going to shoot under. Can't we just shoot the lighting itself to set the custom WB? Will the white and gray cards give different WB compared to each other? And, why is it called white or gray card?

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Old Mar 21, 2005, 9:23 PM   #8
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The problem with "shooting the lighting" (if I understand you correctly) is that the single light (or even a few) really isn't all the light on the subject. The absolute best thing to do is to put a white card exactly where the subject is, then take a picture of that. You want the card to be in exactly the same light as the subject will be.

You take the picture of the card instead of the light because the light isn't necessarily white. You *have* to take the picture of something that you can then tell the camera "this is white" and will will say "well, I see a 5% yellow... so I'll remember to remove 5% yellow from all the pictures."

I believe you should use a white card, not a gray card, for white balance. A gray card is usually used to test exposure settings. A white card is used as a known "white" thing, that can be used to color correct with. I could be wrong with this, but I believe you should use a white, not gray, card.

A "white card" is called that because it is white. It is absolutely white with no trace of color. You'll be surprised how many things (like "white paper") isn't really white, but has a slight color cast to it. A gray card is 18% gray. It reflects an amount of light which the meter in your camera expects, so it knows how to properly expose a picture if you meter it off a grey card. This is useful because if you point your camera at a man in a tux the camera will try to turn it gray. Same with a woman in a white wedding dress. The camera thinks the thing being metered off of is 18% grey. If you *actually* do that (meter off the card) then you'll have the proper exposure setting for that lighting.

Does that help?

Eric
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