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Author Topic: Multi-camera color balance  (Read 3242 times)

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Offline Elana

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Multi-camera color balance
« on: June 17, 2014, 12:49:18 AM »
Recently did a shoot w/ 3 cameras, Canon Vixia HF20 camcorder (wide left), Panasonic Lumix DMC-GF6 Camera (close left) w/ 14-42mm kit lens, Panasonic Lumix DMC-GF3 camera (right) w/ 14mm kit lens.

http://youtu.be/opUO14x4qRM
http://youtu.be/2H4jPnVQoHM

The color balance of the HF20 is off from the other two, and the GF3 is slightly overexposed (but it's not really that noticeable).

What's the best way to ensure the color balance is "synced" between the 3 cameras the next time I go to do another multi-camera shoot?  Not really used to doing video with more than one camera.  I don't think it looks bad but it would look better if the wide left were a bit brighter to match more closely to the other two.

I used premiere for these two videos, is there a way to adjust it there?  Rendering HD video on my current computer is *incredibly slow*, so I didn't want to just play around w/ filters to see what happened.  I really need a new computer, but can't afford the investment right now for the limited video editing I do.

Thanks

Online ScoobieKW

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Re: Multi-camera color balance
« Reply #1 on: June 17, 2014, 12:57:58 AM »
The standard way to do color camera correction is to shoot video with a color chart in the shot.

http://www.bhphotovideo.com/c/product/465704-REG/DSC_Labs_HCE_Handy_Camette_Test_Chart.html/prm/alsVwDtl

Then you have a common reference point to work against.



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Offline 2manyrocks

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Re: Multi-camera color balance
« Reply #2 on: June 17, 2014, 10:29:31 AM »
As mentioned, use a white balance reference card, but you'll still have some variation between cameras just because the white balance/color temperature settings will vary from model to model.  The reference card will get you closer, but don't expect perfection.

Offline Elana

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Re: Multi-camera color balance
« Reply #3 on: June 18, 2014, 09:28:28 AM »
Thanks a lot.  That helps. I'll get a card for the next time I do a multi camera shoot.

Offline beatkilla

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Re: Multi-camera color balance
« Reply #4 on: June 18, 2014, 09:43:16 AM »
Are you using auto exposure and auto white balance?If so you need to switch to all manual settings,and i think your inquiring more about proper exposure than white balance.

The far wide left is underexposed and the far right is overexposed.

White balance is something you can alter in post production but over exposure you can not adjust.

In your editing software you can adjust color by monitoring the Vectorscope to get accuracy.

Offline shoestringconcerts

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Re: Multi-camera color balance
« Reply #5 on: July 18, 2014, 03:11:26 AM »
You can boost the saturation and boost the gain(exposure) on the wide left shot to get it to better match the other 2 cameras.....I don't work in premiere but you should be able to find tutorials on youtube, look for 'color grading'
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Offline Ultfris101

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Re: Multi-camera color balance
« Reply #6 on: July 18, 2014, 11:07:42 AM »
When recording a show the light levels often vary a lot. I find that my cx550v does it's best to handle it but when there's strong white(r) light it often starts to look overexposed.

if you manually set the exposure how do you compensate for those dynamics?

Here's an example of a show where there was a lot more bright, white light than is even normal for the venue:

https://www.youtube.com/watch?v=yayqLQFs4KI

Would you say this is over exposed?
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Offline Bruce Watson

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Re: Multi-camera color balance
« Reply #7 on: July 18, 2014, 01:10:11 PM »
What's the best way to ensure the color balance is "synced" between the 3 cameras the next time I go to do another multi-camera shoot?

The short answer is, you can't. DSLRs and prosumer video cameras don't in general expose their internal color matrix to you so that you can manipulate it. The lone exception I can think of is the new Pannasonic AJ-PX270. You could match a handful of these to broadcast quality, which is indeed what they are for. You can make these match just about anything, including the Sony and the Canon "looks" and of course other Panasonic cameras as well. But the DSLRs you have are going to have the look that's baked into them. You can only change them in post. Sad but true -- and it's actually a selling point -- the Canon look vs. the Sony look and all that.

Best you can do with your motley collection of cameras is perform a manual white balance. But even then, you are fully at the mercy of the lighting at the venue. If you look at the blue lights across the top back of the stage you'll see that they are probably (but who really knows) LEDs. A serious curse to video. Ain't no way in heck you can white balance to something like that. Just be glad they weren't dimming them down, which can cause all kinds of nasty video artifacts in your footage as your 30fps video deals with LEDs running a duty cycle of 17 Hz. I wouldn't wish that kind of banding on anyone.

All that said, your white balance looks pretty good. A testament to the skill of the engineers who designed and built the cameras. And to the fact that the venue was using lights with enough varied spectrum content that the cameras' white balance algorithms had enough light to work with and made the "correct" decisions.

If anything, I suspect what's bothering you is exposure. The only way around that is manual exposure, and the way to do that reliably is to use a production monitor that can show you a waveform monitor view. Put your skin tones in the range of 40-80 IRE (depending on how dark or light the skin tones actually are, etc.), then match to the other cameras so that they'll show the same thing. Which is good until they change the lights, and since many houses bring up the lights after each song... You and your people have to stay alert. If your monitors have zebras it can make life a little easier for the operators -- you can say set your zebras at 75 IRE and keep the exposure set so that you always see just a little striping on the face (typically a highlight like a cheekbone, forehead, etc.).

But heck, from where I'm sitting you've got nothing to complain about. It looks great. You could tweak it in post to make it better, but you don't have a compelling need to. People will forgive all kinds of sins with video, but low quality audio they won't stand for. As anyone on this board well knows.

I used premiere for these two videos, is there a way to adjust it there?  Rendering HD video on my current computer is *incredibly slow*, so I didn't want to just play around w/ filters to see what happened.  I really need a new computer, but can't afford the investment right now for the limited video editing I do.

My typical workflow is to use a luma curve and a three way color corrector on each camera for basic color correction. These don't add a great deal of processing load to Premiere Pro's workflow, and save you from having to use AE for this which adds a huge amount (since adding an AE process to a PPro edit effectively idles all your processor cores but one, and this has been discussed to death on the Adobe forums a couple of years back, so that's all I'm sayin'). If you can keep it all in PPro, all the better.

Anyway, once you've done the basic color correction, run it through the multi-cam editor and pick your angles. Then you may want to lay another three way color corrector over the final timeline to give it a look that you like (this is technically called "color grading").

I'm not actually explaining this for you OP, but for anyone who comes along later and finds this thread. Based on the clips you've showed us, I suspect you already know most of this.

BTW, one way to lower the processing load is to transcode your footage out of AVCHD. Sort of ruins one of the reasons to use PPro in my book, but it does take a good 4+ core machine to run a single stream of AVCHD cleanly, and you'll need at least 8 cores and speed and memory to do a good job with three cameras all running AVCHD. I'm just saying that transcoding might save you some pain in the short term, but long term you're likely going to be better served by power and memory.

Offline shoestringconcerts

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Re: Multi-camera color balance
« Reply #8 on: July 21, 2014, 02:15:35 AM »


https://www.youtube.com/watch?v=yayqLQFs4KI

Would you say this is over exposed?

This looks fine to me, camcorders don't have the dynamic range needed to handle very dark and very bright that many concerts have. you did the best you can to handle the situation
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Offline NorseHorse

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Re: Multi-camera color balance
« Reply #9 on: July 26, 2014, 12:26:12 PM »
Richmond! Sweet, man.

When using different cameras and even different lenses on identical cameras, there will be color differences.

Step #1: make sure all the cameras have the same approximate settings.  They should all be set to 3200K/tungsten.  There shouldn't be any filters.  Use the "cinema" or widest-dynamic range setting you can.  (Or if that makes the cameras more different, go with a profile that looks the closet for all.)  Turn off any special color saturation, e.g. "vivid".

When you go to editing, edit the cameras on either side of the spectrum to make them similar to whatever camera is between the two.

Best bet -- use cameras that are all the same model.  Makes my life a lot easier.
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Offline fguidry

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Re: Multi-camera color balance
« Reply #10 on: July 27, 2014, 04:19:21 PM »
Do custom white balance on each camera if your cameras support it.

Shoot something white on each camera so you have a reference in post.

Fran

Offline 2manyrocks

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Re: Multi-camera color balance
« Reply #11 on: July 27, 2014, 08:29:34 PM »
What is the reason for setting all the cameras on 3200k tungsten?  Fixed reference point instead of the cameras making automatic adjustments to changes in lighting that are nearly impossible to match up? 


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Re: Multi-camera color balance
« Reply #12 on: August 13, 2014, 02:06:26 PM »
The standard way to do color camera correction is to shoot video with a color chart in the shot.

http://www.bhphotovideo.com/c/product/465704-REG/DSC_Labs_HCE_Handy_Camette_Test_Chart.html/prm/alsVwDtl

Then you have a common reference point to work against.

Shooting with an accurate color reference like above along with waveform monitor / vectorscope plug-in's and proc/encoder controls of the video in post can help you color and level match the cameras.
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Re: Multi-camera color balance
« Reply #13 on: August 13, 2014, 02:10:22 PM »
Do custom white balance on each camera if your cameras support it.

Shoot something white on each camera so you have a reference in post.

Fran

That's the old trick I used in TV when I used to do video.  Shoot a white sheet of cardboard or piece of paper (worst case) or even a drum head (if it's white) and use manual white balance.  Your cameras should be "close enough" that it won't be noticeable if you go that route.

Offline NorseHorse

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Re: Multi-camera color balance
« Reply #14 on: September 14, 2014, 10:29:04 AM »
Even filming a white sheet will not help you get close enough to be "legit" when you are using different brand/model cameras, but manually balancing is a great place to start.  Go into the settings and make sure any presets are turned off.  I did one gig with five matched cameras.  The newest one hadn't had all the settings cleared, and it was very difficult to match the other [same model] cameras.

And yes, I always set all cameras to the same color temperature.  Leaving it on automatic is a recipe for unwanted and uncoordinated changes.

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