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Old June 6th, 2011, 04:17 AM   #1
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white balance in PP different from A/B

EX3. Within a Picture Profile you can set the white balance. In a certain profile I set it to 4300, When you set the WB switch on the left of the body to PRESET it uses the white balance as set in the PP. You can however also set it to A (auto) or B. In B I have my whitebalance set to 4300. This means that when I switch from PRESET to B the whitebalance setting goes from 4300 to 4300 and thus stays the same. However, when I do this the color temparature of my footage changes significantly. Though the viewfinder indicates 4300 in both situations, the picture turns much 'greener' when using PRESET and thus 4300 set in the picture profile. How does this happen?
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Old June 6th, 2011, 06:38 AM   #2
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Re: white balance in PP different from A/B

Quote:
Originally Posted by Cees van Kempen View Post
EX3. Within a Picture Profile you can set the white balance. In a certain profile I set it to 4300, When you set the WB switch on the left of the body to PRESET it uses the white balance as set in the PP. You can however also set it to A (auto) or B. In B I have my whitebalance set to 4300. This means that when I switch from PRESET to B the whitebalance setting goes from 4300 to 4300 and thus stays the same. However, when I do this the color temparature of my footage changes significantly. Though the viewfinder indicates 4300 in both situations, the picture turns much 'greener' when using PRESET and thus 4300 set in the picture profile. How does this happen?
First of all, "A" does not equal "auto".

The "A" and "B" switch positions of the white balance switch allow you to store two different custom white balance values. However, "B" is set at the factory to activate "ATW" which is auto-white balance. So, unless you change the appropriate menu setting, then "B" is the one that is auto -- not "A".

The reason 4300K isn't the same with the two white balance methods is because that display in the viewfinder is just a very crude way of giving an approximation of the actual white balance. In some ways it is a meaningless number. There's a lot more to the white balance then just one simple number -- even if the camera makes it appear that way. Here's an example: Imagine if you had a pair of audio equalizers that each had four different band settings. One of the bands is set the same on both equalizers (4300k) and we don't know what the other three bands are set on. So, the odds of the sound from both equalizers sounding the same would be low. It's the same way with camera, except with light.


Another reason for the difference is that you may have "Offset White" white turned on. Check the menus.

If you have a copy of my EX1/EX1R training DVD it might be worth it to take another look at the white balance chapter because there is more to explaining WB than I have time to write here.

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Old June 6th, 2011, 01:35 PM   #3
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Re: white balance in PP different from A/B

If you are at 4300 I imagine you are under flourescents which generally have excess green light. The white balance will adjust for the excess green but the preset will not.
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Old June 7th, 2011, 09:19 AM   #4
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Re: white balance in PP different from A/B

Doug, you are right. I mixed up A and B. I switched from PRESET to A and not to B.

Offset White is switched off.

Leonard, I im shooting a pair of kestrels breeding on my loft in a room with a lot of hay. Only daylight coming in through some openings in the wall. The pair is breeding just beside one of the openings. Though it is daylight, the presence of the hay and wooden construction inside gives a specific 'color temperature'. So a did a white balance check with a white (gray) object and came to 4300, which I set in A. Because I film there quite a lot I decided to copy the PP I usually use, only changing the white balance to 4300 in the PP. I then noticed that using the PP with 4300 gives a quite different result from using the same PP, but setting the WB switch to A, and thus also 4300. The latter gives the rseult I want. I know what to do now, but was (am) just wondering what happened and why.
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Old June 9th, 2011, 01:34 AM   #5
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Re: white balance in PP different from A/B

There are 2 possible explanations:

1. If there is some greenish light refllected into the scene then the Preset would look green while the white balance would balance it out.
The white balance button takes the green- magenta axis into account while preset doesn't.

2. Its also possible that your PreSet and white balance circuits aren't matched well. You can test this by balancing under a known color temp like a tungstun bulb for 3200, or bright sun for 5600. My Preset used to be more magenta than my white balance until I sent it to Sony and they fixed it.

I have tended to find that barring green or magenta issues that if preset and a white balance share the same color temp they should look pretty much the same.

If your preset tends towards green, you might be able to fix it by adding magenta in the phase menu item. Unfortunately this will also make the white balance more magenta un less you set a different PP for PreSet & White Balance modes.
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Old June 9th, 2011, 01:34 PM   #6
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Re: white balance in PP different from A/B

Leonard,

I think it's explanation 1. Now that I know it's easy to deal with it.

Thanks,

Cees
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Old June 12th, 2011, 02:07 AM   #7
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Re: white balance in PP different from A/B

Cees, Don't feel bad, It can fool a tech also - even the other way around.

After getting a new board in my camera last year I noticed the preset was more magenta than the white balance and my friend's cameras were fine. Sent it down to Sony and the tech said they were matching perfectly at his desk. So I asked him if he was under flourescent light. The answer was Yes.

In that case the magenta preset corrected what should have looked green (like yours) under the flourescents.
The Sony tech took the camera into the testing room where it was tungsten and saw that it indeed was balancing too magenta!
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