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Old November 28th, 2012, 11:39 AM   #1
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White balance conundrum...

Yesterday I was scouting an office location for a shoot today, and the room we're shooting in largely illuminated by light filtering through those 90's era greenish reflective glass panels that we see on so many office buildings. Visually the light coming through the windows was a yellow green hue.

The problem is not that the camera totally misread the color as being in the 7800-8700k range... I'm used to that with this camera. It consistently reads my kino-flos at 6800 and produces a yellow result, so we manually set the camera to 5800 for best results.

The issue is this...in hunting around for a correct white balance I hit on 6500k first using the "push wb" feature. This looked good in camera, but as I shoot in log...it's always hard to tell. Later I dialed in 6500k using the kelvin set function and shot another test clip. When I brought both clips into xf utility, and checked metadata...they have identical WB settings except for the method of achieving white balance (push versus kelvin input), but the color response couldn't be more different...

(also amazing what it did to the models pants and hair... :-)
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White balance conundrum...-screen-shot-2012-11-28-9.32.39-am.png   White balance conundrum...-screen-shot-2012-11-28-9.32.07-am.png  

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Old November 28th, 2012, 12:04 PM   #2
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Re: White balance conundrum...

Dialing in Kelvin will not take out any green hue from windows that have ND or flourescent fixtures. If you want to take out the green in camera you have to white balance the camera. Sometimes just tilting the white card in different direction (toward the green source) can dramatically change the white balance.

Same can be said of outside sources, shade, full sun.
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Old November 28th, 2012, 12:25 PM   #3
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Re: White balance conundrum...

So are you saying that the camera, in addition to setting the kelvin at a measured value (when using push white balance), is also applying a tint to correct beyond the base kelvin temperature? (This is how still cameras work, but I assumed that video didn't as you have no control over tint beyond kelvin -- other than going deeper into the camera setup via color matrix etc). If so...I've learned something.

Barry
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Old November 28th, 2012, 01:00 PM   #4
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Re: White balance conundrum...

Quote:
Originally Posted by Barry Goyette View Post
So are you saying that the camera, in addition to setting the kelvin at a measured value (when using push white balance), is also applying a tint to correct beyond the base kelvin temperature?
A camera that is white balanced against a white card makes adjustments to the red, green and blue channels at the proc amp to try to bring all three signals up to equal balance, thereby creating white (colour additive model: equal parts of red, green and blue = white)

A camera that is set to a "known" colour temperature is making adjustments to the proc amps based on assumptions around spectography of the light and is best used for "normal" light: tungsten, HMI, daylight and NOT heavily "polluted" spectographic sources like sodium vapour/halide, LED and fluorescent which contain peaks in the spectrum that are not linear like other sources.

Colour temperature is not the EXCLUSIVE representation of colour spectrum. It is far more a representation of where on the Red/Blue continuum the light lies.
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Old November 28th, 2012, 01:39 PM   #5
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Re: White balance conundrum...

I have a lot of problems with getting correct white color balance with this camera more than any other that I have owned. There seems to be a green tint happening and small adjustments with a white card, a slight turn etc...produces different results. I now just dial in a setting for outdoors with this and this is usually 56k for a sunny day here in Aus. I recall a picture profile from another forum that is downloadable that fixes this problem but I haven't loaded this in yet,I might do this today and get back with some results.

I also shoot a lot of green screen and man what a headache I have had with this green tint that I stopped using the C300.

Its a subtle green tint that I see and most would not see this but I do.
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Old November 28th, 2012, 02:41 PM   #6
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Re: White balance conundrum...

Simon,
Read this and try one of these profiles if you don't use CLog.

Canon C300 Scene Files from AbelCine | CineTechnica
I've been using the JR45CINE profile with very good results.

None of this has to do with white balance however.
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Old November 28th, 2012, 03:18 PM   #7
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Re: White balance conundrum...

Thanks Bob,

I forgot about that info, I'll read this again.
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Old November 28th, 2012, 03:55 PM   #8
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Re: White balance conundrum...

Thanks Bob I have been dealing with the same issue. Forgot Andy put together the PP, just downloaded and will give a few a shot.
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Old November 28th, 2012, 04:06 PM   #9
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Re: White balance conundrum...

Hi Paul,

Here is a link to another PP for the C300. I have found the TRULog pretty good for getting this green tint. I need to do more testing though before I commit this as a profile.

Sorry I mean to get rid of the green tint.

More Canon C300 CP's! - Cinema EOS User Forum
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Old November 28th, 2012, 04:14 PM   #10
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Re: White balance conundrum...

Hi Simon,

Thanks you sent me these in an email. I have been using the truvid2 with decent results. But will try the TRUlog. Time for me to only shoot LOG with my type of shooting it will be worth it.

Hope you are saying the TRUlog gets rid of the green tint? Not getting it?
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Old November 28th, 2012, 04:30 PM   #11
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Re: White balance conundrum...

I forgot I sent you those, getting old.

It seems to help with getting rid of the green tint with my limited shooting time with it. One thing is this profile is a bit less saturated than the Canon CLog. Get into Clog man it will really help with your stuff.
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Old November 28th, 2012, 04:33 PM   #12
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Re: White balance conundrum...

Will use CLOG for my next test shoot prior to the next job. But right now I have 10 balls in the air. Trying to catch them all with a little juggle, all fun.
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Old November 28th, 2012, 04:38 PM   #13
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Re: White balance conundrum...

How's it all gong with your rig anyway? I have just purchased the Small HD DP4 EVF to add onto the 300.

I'm shooting most of my commercial stuff with the 300 and loving it. I do hope a firmware comes out soon.
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Old November 28th, 2012, 05:10 PM   #14
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Re: White balance conundrum...

Its making money, 30 days since 1 Oct. My Movcam rig with a few mods is great. Stable, light, easy to hold all day, packs small.

Agree with the firmware update. Also trying to get a extended warranty but can't get Canon to get back in touch with me. I am CPS Platinum member with my still gear be nice if they would let you add the C300 to that but they don't.
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Old November 29th, 2012, 10:43 PM   #15
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Re: White balance conundrum...

There is another option for dealing with the green tint. I was the B camera on a two camera C300 shoot recently.We used the EOS standard CP preset and the Tungsten WB preset hoping to match, but my camera had a green tint. There was no time to get into Matrix settings. We had some luck white balancing through 1/4 blue and 1/4 green gel swatches, and then I tried the White Balance setting in the CP menu. In this particular case, I used +4 R Gain, -2 G Gain, -2 B Gain to achieve a close match. The white balance offsets seem to affect all presets and any subsequent white balances. I'm not sure if you would want to do this in C-Log. Technically, you are locked out, although you can get around that, but you would probably just dial out green in grading rather than in the field.
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