C300: MKII White Balance best practice?

A

Alex P

Member
Trying to white balance my C300 MKII to a set of Aputure Light Storm 300D lights I can´t get a consistent kelvin reading from the camera. Auto White Balance on an 18% grey card gives an reading of 6000K. Manual White Balance of an 18% grey card (Lasolite Ezybalance) gives a reading of 5500K, which gives some very warm looking footage. Dailling in 5500K on the Kelvin setting gives a much cooler look to the footage? Manual balancing of non reflective white gives a reading of 5100K, all readings in the exact same lightning conditions (Single light source - Aputure 300D with Aputure Light Dome).

Ever since I got the C300 MkII more than a year ago, I´ve had a hard time achieving correct white balance with the camera. Most of the time having to correct a little in post.

Any tips for best practice white balance with the C300 MKII? Should I just spend the money and get a dedicated color meter?

Thanks

/Alex
 
First, let's distinguish what you mean when you say "auto white balance" and "manual white balance". To me, "auto white" you are pointing the camera at a white target and activating the auto white balance feature of the camera and it's going to adjust its color channels to make the target white. And when you say "manual white", you are just activating one of the presets in the camera and not actually adjusting any of the parameters 'manually'. If a light source is not "true" and you are just using a preset, the camera is expecting to see a true 3200k or true 5500k, etc., then the color will be off because there has been no compensation for a light source out of the expected, preset parameters. The same is true for "dialing in" the kelvin temp., if the light source is too far outside of the norm(ex: an LED that pushes green).
 
By Auto White Balance I mean AWB setting on the camera, and pointing it at a white or grey object that fills the whole screen. By manual I mean "Custom White Balance" - point the camera at a white/grey object filling the whole screen and press SET to set the white balance. When I use the Custom White Balance I get a reading of 5500K (The Aputure lights are rated at 5500K) but the final image is very warm/yellow. However if I switch over to the K setting on the camera, dailling in the same 5500K the image is way cooler/bluish. What i don´t understand is the difference in final image with the same 5500K setting? Furthermore the different results in kelvin reading balancing of a white vs grey object.

@jcs: I would love to try out the Cine Meter II app, but i can't find a EU dealer of the Luxi photosphere which is needed for the color metering feature.
 
1. I would suggest never using AWB. You will have inconsistent looking footage as it is constantly adjusting itself.
2. When you set a Custom White Balance the camera is adjusting more than just how warm or cool the image is. To render your white reference card correctly it will subtract or add custom amounts of color gain to individual channels (RGB).
3. When you set your white balance to the adjustable kelvin setting you are only affecting the Red and Blue channel balance.

These are my observations as a C300 MKII owner/operator.
 
Those Lasolite Ezybalance cards are not white. At least mine isn't.

I never use the AWB setting, but I regularly use the custom white balance. Part of the problem with LED's is that they are not full spectrum so they can easily screw up the sensing of the perception of white based on just the RGB values from the sensor. Also, I've noticed that the Kelvin temperature reading when a custom white balance is done can be a little odd. Most LED's don't have a very good CRI and the kelvin reading given by the camera is just an approximation. The green or magenta bias from LED's can give you a Kelvin reading from AWB that doesn't at all match the image when the same kelvin is entered manually for the white balance. It is a bit of a guessing game.

For me, I tend to rely on the RGB waveform and make sure that I get a true white source for the custom white balance. Make sure the RGB values on the waveform are all the same and trust the sensor. If I have to set a kelvin, I will also use the RBG waveform to make sure that the R and B peaks are approximately the same.
 
I also tend to avoid AWB, it was mostly to check if there would be some consistency in two different methods of white balancing the camera.

Good idea with the RGB waveform, I will definitely try that.

I do a lot of coporate interviews/talking heads, and have to deal with different mixed lightning conditions. It would be great if other C300 MKII users/owners would share their "White Balance workflows" when working with mixed lightning. I use a GH4 and GH5 for B/C cam, and with those I get great results with custom white balance of the grey card, unfortunately they don't give a kelvin reading.
 
The RGB waveform is a good idea. I've also been carrying around a sheet of white diffusion, like Lee's 216, drape it over the front of the lens, and set the custom white balance. It's a super cheap version of the Expodisc.
 
Alex P said:
@jcs: I would love to try out the Cine Meter II app, but i can't find a EU dealer of the Luxi photosphere which is needed for the color metering feature.
Click to expand...

You don't need the Luxi, you can use a gray card (white paper can also get close if nothing else available)
 
drummondb said:
The RGB waveform is a good idea. I've also been carrying around a sheet of white diffusion, like Lee's 216, drape it over the front of the lens, and set the custom white balance. It's a super cheap version of the Expodisc.
Click to expand...


The RGB parade waveform is your best bet for actually knowing what you are getting white balance wise. Get the white in your frame all at the same level and you should be good to go.

You don’t mention what monitor device you are using to judge color .... If you are working off the LCD on the camera for critical color judgment, that can be an iffy proposition.
 
I always use a combination of my 2017 iMac, an iPad pro and a LG UHD televison to judge color. On location I "rely on" the camera LCD, however it´s a bit of guessing with the built in Rec709 lut.

After more testing I think that some of the issue, was/is me having to high expectations for the Aputure 300d lights, expecting/dreaming of close to HMI levels whites and skin tones.

I did find though, that there is a very defined shift in the overall tonality of the image with only +/- 100 Kelvin on the camera, in this case it´s between 5300K and 5400K, and none om them seems right, its either to cold or to warm. When I say warm it is also a matter of the green in the image is becoming very noticeable. I have experienced this with different light setups as well.
 
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Alex P said:
I

I did find though, that there is a very defined shift in the overall tonality of the image with only +/- 100 Kelvin on the camera, in this case it´s between 5300K and 5400K, and none om them seems right, its either to cold or to warm. When I say warm it is also a matter of the green in the image is becoming very noticeable. I have experienced this with different light setups as well.
Click to expand...


Don’t know if this applies to your case or not , but I have noticed with my 300 mk2 that a manual white balance gave a result where red and blue channels were always slightly elevated compared to green. So what i did in the camera profile that I often use was to make an edit in the white balance setting and reduced the blue and red gain by a pioint or two each to equalize the individual channels when making a white balance. you could effectivelty do the reverse of this by adding a point or two of red and blue gain to your camera profile to null out the green bias . You would be surprised what a point or two shift in the camera profile white balance setting can do for the image. In my case, it was the difference between pretty good and the camera sees things the way I see things, which is a great place to work from.

Edit: I would only make this CP edit if I wanted to affect overall white balance in all situations not for a specific lighting situation with specific lights .... LED lights are all over the map color spectrum wise even tough to the eye they may look good. Cameras are not as easily fooled by skewed lighting spectrum as our eyes are.
 
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And....make sure you did a black balance at the start of the day before you do any WB......and on the AWB, it will always drift on you so don't use it.

Jim Martin
CinemaWorks
 
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