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Old August 3rd, 2010, 02:23 PM   #1
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Hmmm...Maybe Goofed on White Balance?

So we just finished our first two camera shoot and are now editing our video in Vegas. It looks great except for the fact that colors are very *slightly* off between the cameras. It's not terrible, but it's noticeable to my extremely critical eye.

So I'm wondering -- did we white balance incorrectly? We used two identical Canon XH-A1s. One was pointed squarely at the subject and one was off to the subject's side. When we white balanced, we placed each camera into its respective position (either in front of the subject or to the side) and then had the subject hold up the white card. So we white balanced both cameras from each's respective position.

Is that right? Or should I have white balanced both cameras from the same very spot and then moved the cameras to their respective positions?

Thanks for any thoughts on this.

Norm
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Old August 3rd, 2010, 03:04 PM   #2
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White balance from the same position, then separate the cameras.
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Old August 3rd, 2010, 03:10 PM   #3
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Gotcha. Fortunately Vegas does WB correction. Hopefully that'll fix it up well enough.
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Old August 3rd, 2010, 03:49 PM   #4
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Perrone's response is right of course IF the primary concern is that one object/subject is the centre of attention and must be identical in both cameras. IF however you need a larger room to look the same on camera from two positions and the various areas fall under different light, your approach would need to reflect that. White balancing is part hard science, part art and part "fudging" to get the intended result.
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Old August 3rd, 2010, 04:02 PM   #5
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Honestly, these days I prefer to saturate the blue channel with the lighting, and not even worry about a white balance. Our lighting is so blue deficient in most cases, doing a white balance does more harm than good.
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Old August 3rd, 2010, 04:06 PM   #6
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Quote:
Originally Posted by Shaun Roemich View Post
Perrone's response is right of course IF the primary concern is that one object/subject is the centre of attention and must be identical in both cameras. IF however you need a larger room to look the same on camera from two positions and the various areas fall under different light, your approach would need to reflect that. White balancing is part hard science, part art and part "fudging" to get the intended result.
Hmmm...interesting...OK, let me provide more details and see what you think.

We shot an MMA fight in a boxing ring. We used two cameras like I mentioned before. The ring canvas was sort of a grayish blue. From one camera the canvas is a bit bluer than the other. I would have liked the canvas to appear identical from both cameras.
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Old August 3rd, 2010, 04:28 PM   #7
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I'm going to take Perrone's previous response as very tongue in cheek - what I meant by my previous comment was that white balancing to exactly the same temperature MAY NOT ALWAY be what you NEED in order for your MOST IMPORTANT item to look right. If one camera position is lit primarily by daylight and one is lit primarily by tungsten, you'd be doing yourself a disservice by white balancing to the SAME temperature - this happens routinely in mixed lighting environments where cameras are separated by some distance. And my comment was NOT intended as a correction of Perrone but instead as a further discussion of what white balancing SHOULD be used for, which is making as natural an image as possible and providing a seamless a transition between multiple camera angles.
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Old August 3rd, 2010, 05:06 PM   #8
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Quote:
Originally Posted by Norm Kaiser View Post
From one camera the canvas is a bit bluer than the other. I would have liked the canvas to appear identical from both cameras.
Keep in mind that big show live broadcasts often have studio cameras that are manually and CONSTANTLY updated by a Shader or Colourist who uses a Camera Control Unit (CCU) in tandem with reference monitors and 'scopes in the control room to match cameras EXACTLY. Even pro level cameras may have SLIGHT difference in colour, even if all settings and colour balance are identical. As well, MINOR discrepancies in exposure can also exacerbate the issue.

Sounds like a relatively quick fix in post - for multicamera live switched, this is potentially much more of an issue...
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Old August 3rd, 2010, 06:32 PM   #9
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Prosumer cameras rarely match, even when on a preset, they are just not that consistent. Add in the variables of if the two LCDs on the camera are not adjusted identically and don't match, you won't be able to see what you are trying to match accurately anyway. If you have a pro, calibrated monitor with two line inputs, you can A/B between them to at least get the colors in the ball park.

I agree with Perrone. There is a good post, I think somewhere by Frank Glencairn, that shows why you may be much better only operating your prosumer camera at 5600k WB, regardless of the type of lighting. My advice would be to shoot 5600k preset on both cameras, shoot a chip chart under the lighting you will be shooting under and use Color, Colorista or whatever PC users use to color correct to make them match and correct them in post. You aren't going to get an exact match with prosumer cameras and as Shaun posted, you need pro cameras with CCUs and a really talented engineer painting the cameras in real time anyway to get a great match and that is with expensive pro cameras.

Or you can do what I did a few weeks ago. I shot an eight camera concert. None of the cameras matched in the least and I wanted it that way. It is a mixed media approach that can work well for music and live events.

Dan

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Old August 3rd, 2010, 09:16 PM   #10
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After watching Panavision's series on digital sensor technology and lighting, I completely changed how I do white balancing. I honestly can't remember I did a true white balance on a camera I was operating. You should SEE the looks I get on set as a DP when I let the image go significantly blue. Not enough to clip the channel, but enough to know things aren't "right".

Shooting on a tungsten preset assumes you will have an abundance of RED/Orange light and a dearth of blue light. If you feed a lot of blue in at this setting, you'll go blue very quickly. Enough to cause clipping in the blue channel. If you move to a pre-set of 4500k, you'll go blue with daylight fixtures or lighting, but probably not enough to clip anywhere. If you go with a daylight preset, but can get the blue channel to still go blue, you can ensure that you are getting a fairly clean blue channel in your footage, and it will look REMARKABLY better than most. Certainly better than if you shot tungsten sources and white balanced in the camera. That is just a recipe for noisy video.
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Old August 4th, 2010, 08:20 PM   #11
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My apologies - I thought Perrone was being facetious. I haven't heard of this "loading" up of the colour channels before.

This discussion is interesting to me: coming from the "old" days of pre filtration on camera where CTO filters were placed in the Filter Wheel to change 5600k (or steps such as 4300k, 6300k such as on the D600 BetaSP camcorder) light down to 3200k (where CCDs were "naturally" balanced), I though the loss of filter wheels in prosumer cameras was asking A LOT of the proc amp, in terms of leveling out the balance of the red, green and blue channels.

This sounds like an interesting solution. I will look more into it as I already shoot wide gamut in anticipation of colour correction in post.
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Old August 4th, 2010, 08:43 PM   #12
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Shaun:

Check this out. Makes perfect sense to me and I agree, my HPX170 looks a LOT better on the 5600k preset.

Why white balancing in your camera, may be a bad idea. Frank Glencairn

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Old August 4th, 2010, 08:55 PM   #13
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Thanks for that Dan.

It's funny, when I FIRST started shooting DVCam on a Sony PD150, we were in post and I hit the Blue Only button on the broadcast monitor and was FLOORED by just how much mosquito noise there was. It was obvious that a LOT of material was being "thrown away". Never really gave a lot of thought about WHAT to do about it though...
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Old August 5th, 2010, 12:20 AM   #14
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This is another reason that daylight balanced lighting like HMI and 5500k or 6500k balanced fluos are a godsend for getting clean video; I wish I could get all 6500k sources for scenes without a lot of skin tones. Honestly, tungsten light looks really nice on Caucasian skin.


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Old August 5th, 2010, 12:33 AM   #15
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Quote:
Originally Posted by Perrone Ford View Post
Honestly, tungsten light looks really nice on Caucasian skin.
Shooting news, we always had DIMMABLE tungsten on camera lights and outdoors if it was overcast and the person we were interviewing looked a bit pale or washed out, I'd dial in JUST A BIT of tungsten, even if prevailing temp was over 6500K. Added just enough warmth to make the face POP.
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