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What is the point of White Balancing

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Declan Smith
What is the point of White Balancing
on Dec 8, 2014 at 1:37:51 am
Last Edited By Declan Smith on Dec 8, 2014 at 1:54:04 am

We've all been taught to always white balance before shooting, which is something that I would never fail to do (ok, perhaps occasionally!!).

But, I have recently got another Canon XLH1. On a multi camera shoot, both XLH1's WB was set to preset Tungstun yet back in the edit there is quite a difference between them. As they are matching cameras, I was a little surprised. I took this further and have done WB tests against both the XLH1's, a Canon 7D, and even an XL2.

Even on custom white balance (against a grey card in controlled lighting conditions) there is no consistency between them. I have done tests under a daylight bulb on Daylight Preset, Daylight Custom, 6400k, and then under a tungsten light with Tungstun preset, Tungstun custom, and 3200k. Now even if there is a variance between the various cameras, I would have expected each camera to maintain WB under different conditions, particularly when using custom WB. Not so. There is so much variance I wasn't expecting, and this seems to be with every camera as well. So it makes me wonder 'what's the point of whitebalancing?' because all this variance means colour correction will have to be done in post anyway. This also makes the use of custom presets more troublesome as they base themselves on the basic WB.

Am I missing something fundamental or are my expectations unreaslitic?

Below are the Stills

6400k


Daylight Custom


Daylight Preset


3200k



Tungstun Custom


Tungstun Preset


Declan Smith
http://www.madpanic.tv
After Effects CS6/ FCS3 / Canon XLH1 / Canon 7D / Reason / Cubase

"it's either binary or it's not"


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Todd Terry
Re: What is the point of White Balancing
on Dec 8, 2014 at 3:45:49 am

I think your expectations might be too high... I think the comparisons of your two H1 cameras was actually pretty darn close.

I did not look at the other cameras, just the H1s... the other cameras are comparing apples and oranges, they are irrelevant and shouldn't be expected to match perfectly. Since one would expect to normally do at least some color grading to most any footage, I think those two are certainly well within tolerance for matching.

I would ask, are both H1 bodies set up EXACTLY the same... as in, the exact same picture profile? I mean, within the menu there are 23 (I think it's 23) different adjustable parameters that can be tweaked to precisely paint the image. If those settings aren't exactly the same on both cameras, right down to the tiniest digit, the cameras may not match.

You didn't say so, but I'm assuming that you are using the same identical lens on both bodies (matched lenses of the same make, model, vintage, and batch). If two different lenses aren't matched, they can have wildly different color balance properties. I usually shoot with a matched set of superspeed primes as my primary glass... and they all match perfectly. But in the occasional instances that I need to use a zoom lens, I have to adjust my color temperature as my zoom lens (a Russian FOTON) is much warmer than the primes... and I mean a lot... like more than a thousand degrees warmer.

Before we retired it two years ago, I shot daily with the H1 since they very first came out. I'll have to say, I don't think that I actually set an actual "white balance" even once. One of the things I liked about the H1 was that you could dial in the exactly color temperature (by degree) that you wanted (I know that seems common now, but it was a bit radical at the time)... so I always just did it that way.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Declan Smith
Re: What is the point of White Balancing
on Dec 8, 2014 at 8:40:56 pm

Hi Todd,

You're probably right about my expectations. This is the first time I've had two 'identical' cameras so I've always put white balance / colour differences down to the fact that the mulit-camera shoots I've worked on are using different cameras (which like you say is like comparing apples and oranges) and need colour correcting in post. I included them just to see if anything was consistent / close.

I must admit I hadn't realised that lenses themselves could make such a difference. To answer your question, both XLH1's are set at factory default, no presets, and both using the 20x stock lens for all the pictures in this thread. They are not matched as such in that they are just the lenses that came with the cameras and I haven't tried interchanging them.

I've included some re-arrangements of the tests showing the three daylight shots of one camera on the same slide, three shots of tungsten on one slide for both cameras. I've also shown the RGB settings of the grey patch. The colour is different from Fixed setting to degrees kelvin setting to custom, probably because the light source wasn't exactly tungsten or 3200k. When comparing like these though, I've noticed that the custom white balance is king and actually shows (on a per camera basis) that the cameras do hold white balance. i.e. on XLH1-1, custom WB on Tungstun is more or less the same as custom WB on daylight and the difference between XLH1-1 and XLH1-2 is negligible.

What is at odds, however, are the presets and the colour temperature. Comparing say both the 6400k slides, or both the 3200k, or both tungsten presets or both daylight presets, they are different between the cameras. So in my mind, the only 'safe' WB setting to use is custom. XLH1-1 is more red in the preset / kelvin colour temperature or the XLH1-2 is more green.

For many things, I can use custom WB, but sometimes it's more convenient to use the presets (or the colour temperature). One of the cameras has to go back for other repairs so wondered if this is something that is feasible to get corrected or whether to just fix these issue in post. I am more than comfortable with doing things in post production but my opinion over the years has gone almost 180 degrees in that the more that is right in pre-prod, the less work needed in post.

XLH1-1 Daylight


XLH1-2 Daylight


XLH1-1 Tungstun


XLH1-2 Tungstun


Declan Smith
http://www.madpanic.tv
After Effects CS6/ FCS3 / Canon XLH1 / Canon 7D / Reason / Cubase

"it's either binary or it's not"


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Todd Terry
Re: What is the point of White Balancing
on Dec 8, 2014 at 8:58:45 pm

I'd personally "fix it in post," even though I hate when people say that, because you are right in that it is usually easier/better/faster/cheaper to do it right in the first place.

However, since I virtually always do at least some kind of color grading to footage (even though it might be very minimal) it would be easy enough to match them. If you never do any color grading though and are reliant on camera raw footage being "good to go" then that might not be a workable solution for you.

And yes, lenses can make a drastic difference. "Real" cine lenses are known by their properties, which includes color temps. For example Cooke lenses are very warm, Zeiss lenses tend to be cooler and more contrasty, etc. And even of the same type/model of lens you can't expect them to look the same unless they are specifically from a matched set. They might be close, but not exact. Now the stock H1 lens is a very good lens, for what it is... but still it is basically a thousand-buck prosumer lens compared to a real Cannon cine zoom lens that might cost as much as 50x that...literally. An inexpensive lens is not going to have the same quality control or purposeful matching that the cine lenses do. Your lenses were very likely not from the same exact lot... they might have been made (and coated, which is the important part) week or months or even years apart.

I'd run a quick test with the two H1 bodies but using the same lens. If it is a lens issue, that would show you.

I'd really doubt that a technician could tweak-to-match them. If they can, they would A) really have to know what they were doing, and B) they would have to have both H1 bodies (and lenses, now that I think about it).

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Declan Smith
Re: What is the point of White Balancing
on Dec 9, 2014 at 12:59:26 pm

You're right. Now that I've seen that the custom WB between both XLH1s does get them almost identical, in those situations all is good, and for the others a simple primary colour correction will do. I do mostly colour grade anyway, so can fix any differences if needed like you say. I generally fix white balance issues by number and it would almost certainly be constant under a particular preset for the setups I'm talking about (event filming). Certainly learned some things going through this exercise and particularly about the lenses.

Thanks for your help.

Declan Smith
http://www.madpanic.tv
After Effects CS6/ FCS3 / Canon XLH1 / Canon 7D / Reason / Cubase

"it's either binary or it's not"


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Craig Alan
Re: What is the point of White Balancing
on Dec 22, 2014 at 4:01:03 pm

You could hook up each camera to a broadcast monitor with scopes and color correct during a shoot to a degree. Even a slightly different angle or black levels or lens will change the perceived color. Also do we really want to white balance out the look of sunset or the gel that a lighting designer added to a shot? Is there something really wrong with having natural light coming in a window when using 3200 lamps? That too is a rule. Gel the window. Are any two outdoor shots the same color temp? Depends on the clouds and anything else that filters the light. Does natural sunlight through a window really match daylight bulbs? Kino flos are warmer than fresnels of the same spec - do you ever mix these two light sources? Do you ever dim the hair light which warms up the temp? I'm beginning to believe that white balancing is a relative variable. I'm much more concerned with controlling exposure levels and depth of field. In post you can concentrate on how different shots in the same scene or in sequence play with each other. The human eye/brain will white balance a scene on its own. The camera won't but humans watch the film. I think we are much more sensitive to contrast than we are color accuracy. All that said if you are shooting with multiple cams of the same model, its good practice to have them match so you can cut between them. Just curious - are your tests taken with identical angles to the cards? Is there any way of calibrating the same model camera to match each other?

Mac Pro, macbook pro, Imacs (i7); Canon 5D Mark III/70D, Panasonic AG-HPX170/AG-HPX250P, Canon HV40, Sony Z7U/VX2000/PD170; FCP 6 certified; FCP X write professionally for a variety of media; teach video production in L.A.


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Rich Rubasch
Re: What is the point of White Balancing
on Jan 3, 2015 at 7:52:14 pm

We spent some time creating custom color profiles based on the Abel Cine Tech C300 profile. We matched our 5D Mark II to the C300 very close using these color profile settings. Now we barely have to touch the clips when cut side by side. Took a while but was worth the journey.

Rich Rubasch
Tilt Media Inc.
Video Production, Post, Studio Sound Stage
Founder/President/Editor/Designer/Animator
http://www.tiltmedia.com


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