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Author Topic: using white balance card correctly  (Read 4293 times)

soboyle

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using white balance card correctly
« on: January 03, 2011, 01:52:43 pm »

This one's probably been beaten to death.
I'm doing more color work lately, so want to get reasonably accurate color balance as a starting point. 
I picked up a x-rite passport, and have been shooting the gray card and charts at each location as the light changes.
What I'm finding is that you get quite different results depending on how you hold the card. If shooting under full sun the difference is quite radical if you hold it in the sunlight vs. shading it.

So is there a correct technique for holding the card when shooting in sunlight?
If held directly in the sun I get a very warm light falling on the card, which translates to a cool balance. When the card is shaded it is just the opposite.

PeterAit

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Re: using white balance card correctly
« Reply #1 on: January 03, 2011, 06:09:40 pm »

This i exactly what you would expect. In shade the card is illuminated mostly by sky light, which is blue. This is why shadows in sunlit photos often have a blue cast - it is simply an accurate representation of the light (which the eye can compensate for but the camera cannot). If you're shooting in sunlight it seems likely that the important elements of the image are in sunlight, so use that for the card.
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Nick Rains

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Re: using white balance card correctly
« Reply #2 on: January 03, 2011, 06:36:18 pm »

Yes, your results are as expected.

Accurate colour  for outdoor photography is almost an oxymoron. I find that by using a grey card you run the risk of removing the very colour casts that give the light its qualities. Why would you want to sterilize the light's characteristics?

In a studio setting where product colours are important then a grey card is a good starting point but in outdoor situations I find them superfluous. Shoot raw, set the white balance to daylight and off you go.
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Nick Rains
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Bart_van_der_Wolf

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Re: using white balance card correctly
« Reply #3 on: January 03, 2011, 06:37:10 pm »

So is there a correct technique for holding the card when shooting in sunlight?

I position my reference card/object to be parallel to the main surface of the subject.

Cheers,
Bart
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MarkM

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Re: using white balance card correctly
« Reply #4 on: January 03, 2011, 06:42:48 pm »

Quote
Accurate colour  for outdoor photography is almost an oxymoron. I find that by using a grey card you run the risk of removing the very colour casts that give the light its qualities. Why would you want to sterilize the light's characteristics?

That's my feeling too. I used to let the camera auto white balance, then lightroom would pick up these settings. Everything got neutralized and started to miss the way slide film worked in changing light: changing light=changing colors. Now I use daylight as a starting point and since I have a raw file, I can adjust from there if I choose.
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Wayne Fox

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Re: using white balance card correctly
« Reply #5 on: January 03, 2011, 07:54:07 pm »

I find that by using a grey card you run the risk of removing the very colour casts that give the light its qualities. Why would you want to sterilize the light's characteristics?

Something missed by many.  Shoot a grey card and balance for it in a shot of a sunset, and then wonder where all the beautiful color went ...
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soboyle

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Re: using white balance card correctly
« Reply #6 on: January 03, 2011, 08:03:16 pm »

My thought is that a "correct" white balance is a good place to start, certainly better than auto white balance, and will give consistent balance for the shoot, rather than being all over the place. Using the presets, such as daylight is also a workable solution.

Nick Rains

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Re: using white balance card correctly
« Reply #7 on: January 03, 2011, 08:14:08 pm »

Grey card and auto WB will give similar results by compensating for supposed colour casts. You might actually want those casts when the light is warm.
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Nick Rains
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Bart_van_der_Wolf

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Re: using white balance card correctly
« Reply #8 on: January 04, 2011, 05:20:13 am »

Something missed by many.  Shoot a grey card and balance for it in a shot of a sunset, and then wonder where all the beautiful color went ...

Hi Wayne,

That would suggest the grey card is being used in the wrong way. A grey card should be used to get a neutral reference. Nobody is forced to stop there, in fact it is just step one in getting ones colors right. Same procedure as with shooting a sunset, or when shooting under a heavy tree canopy, or on a green lawn. First one establishes a neutral starting point, next one sets the mood.

By the way, not all grey cards are neutral enough for White balancing, and the positioning/angling of the grey card makes a significant difference.

Cheers,
Bart
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Nick Rains

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Re: using white balance card correctly
« Reply #9 on: January 04, 2011, 05:30:23 am »

Not sure how a grey card can be at all useful in the warm evening light. Why would you want to neutralize the warm colours.

Agree about green casts under trees and open shade so I guess the only ' technique' involved is deciding whether to use a card or not.
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Nick Rains
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NikoJorj

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Re: using white balance card correctly
« Reply #10 on: January 04, 2011, 05:39:50 am »

Grey card and auto WB will give similar results by compensating for supposed colour casts.
With one difference though : gray card is incident metering, autoWB is reflected metering (which is even worse, the worst being probably the pringle-lid-lens-cap solutions).

As said, you generally woudn't want to neutralize the outdoor light (except perhaps the odd case of a portrait under the shade of a tree, quite common for the average Joe the marriage photographer indeed, doh it seems like people have read in my mind as I wrote this).

Otherwise, for better accuracy one may wish to do a complete color calibration with a ColorChecker (ie DNG profile).
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Nicolas from Grenoble
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Bart_van_der_Wolf

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Re: using white balance card correctly
« Reply #11 on: January 04, 2011, 05:59:54 am »

Not sure how a grey card can be at all useful in the warm evening light.

Hi Nick,

It's quite easy. Just WB on the card, and subsequently dial in an amount of color temperature to your liking. This will make sure you eliminated green/magenta casts, and you are strictly setting the ambiance in a consistent way by color temperature. Color temperature represents natural sources of incandescent light with continuous spectra, and objects are perceived as having natural colors (and our eyes can cope with the (re-introduced color temperature) casts involved much better than with e.g. magenta).

Cheers,
Bart
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soboyle

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Re: using white balance card correctly
« Reply #12 on: January 06, 2011, 03:05:51 pm »

I got started with this because I was seeing a slight red cast in images from my 5D mk2.
So I am using the x-rite passport and software to create a profile I can use in LR on the images.
I'm seeing a slight improvement there vs. the Adobe Standard camera profile, and when adding the white balance am getting overall better color quality (vs. my previous way of working with auto WB, because I was often converting to B&W and didn't worry about it).
I do see the point raised by Nick and others: why neutralize a beautiful color cast?
The point is that you don't have to if you don't want to, but you will have a known reference to work from if you choose to do so.
I suppose that setting the camera to a particular WB setting, like daylight, would be similar in that it would give you a consistent starting point from which to correct (or not).
My goal is to get the best color that the camera is capable of producing, so whatever techniques would be helpful in making that easier are what I am after.
« Last Edit: January 06, 2011, 03:37:57 pm by soboyle »
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