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Sekonic C-500 CC index to Resolve tint value correlation


Daniel Reed

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i'm only asking for help on how to convert the Sekonic color meter "CC" index reading to apply to the Resolve "tint" slider value in the camera RAW section.

(no mired/kelvin issues for this.. just the CC value and translating that value for post work)

 

On p12 of the Sekonic manual paraphrased, each CC index number is multiplied by 2.5 to get a Color Correction filter number...

 

OK, that's awesome... for knowing what CC gels to use on lights...

 

...but how does that meg/grn adjustment number relate to the +/- 150 value in many applications (lightroom/resolve)

 

 

I would also like to know how to apply that same meg/grn measurement to shots in post too.

 

 

 

Here's an example: hypothetical fumbled studio shoot.

 

Tungsten lamps, checked/metered in advance, all good.

Power goes out, comes back on an hour later.

one of the bulbs is now dead and is replaced.

In a rush and don't re-meter lights

notice after the talent leaves that something is off with the key (fill bounced)

re-meter, yup for some reason the new lamp shows a CC index value of G2 (previous bulb was 0 on the Sekonic C-500)
Write down the value...
Fast Forward
I am now sitting in front of Resolve and looking at the "tint" slider in camera raw window on the "color" tab.
what do i set the slider to...
+5
-5
+2
-2
.... or something completely different? Please explain in detail.
Thank You so much in advance, I have given myself a headache from googling and re-reading manuals =)
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I asked Sekonic in japan via email and google translate. I'm also working on getting an answer from BM.

If I hear anything, I'll update this post. Thanks

Edited by Daniel Reed
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REPLY FROM SEKONIC:

 

Dear Mr. Daniel Reed,

Thank you for your inquiry.
I am Minoru Oda(Mr) from Sales Operation Sec.
of light meter in Sekonic Corporation in Japan.

Unfortunately, we could not know the unit of "tint" slider value of the software programs in our survey.

As you already know, our color meter measures color temperature of light source. And indicate in kelvin and CC index.
And our 1 CC index is equivalent to 2.5 CC filter number.
However, we do not understand our 1 CC index become what amount of "tint" slider value, because we do not know the unit of "tint"
slider value.
Please kindly ask about the unit of "tint" slider value to the software maker.
The scale might be just a guide, because the software is used for getting favorite color with looking the picture which is affected by
"tint" slider in general, and "tint of picture color" and "the deviation from blackbody locus of light source" are different thing if strictly
speaking.

In addition, if C-500 shows 2G in CC index, the direction of compensation of "tint" slider is needed minus direction (to green direction).

We would like to apologize not to meet for your expectation.

Sincerely yours,

Minoru Oda
Sales Operation Sec.
******************************************************
SEKONIC CORPORATION
7-24-14, Oizumi-Gakuen-Cho,
Nerima-Ku, Tokyo 178-8686
Japan
Sales Operation Sec.

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REPLY FROM BLACKMAGIC:

 

 

Hi Daniel,

The numbers have no direct correlation to specific gels or filters. It's just a variable tint control with a +/- 150 range around the center point.

 

What the settings are doing exactly depends on what raw clip format you are using. In the case of other vendors raw clip formats, whatever their decoding algorithms do when that value is changed. In the case of the BMD raw clips, I don't know exactly what is being done to the image. It doesn't look like a hue rotation exactly. By observation, it appears to be shifting the colors up and down the Green/Magenta axis.

Regards,
Dwaine


Dwaine Maggart
DaVinci Product Support
Blackmagic Design USA

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I find it hard to fathom I'm the only one to wonder about this. If Sekonic has calibrated their color meters to industry standard CC gels, why would Resolve use arbitrary values for their M/G "tint" slider?

If i can match a color R/B shift via a meter and resolve, I suspect i should be able to do the same for M/G shifts.

 

Perhaps this is an oversight on BMD, or they just wanted to get the M/G slider function in there and are still working on it.

Its also entirely possible I am misunderstanding something in terms of colorimetry. Either way, I've asked BMD support to escalate my inquiry.

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  • 8 years later...

I know that this is an old thread, but I just wanted to let you know, Daniel Reed, if you are following this topic, that you are not alone-- I also have been searching for a correlation between Resolve's tint controls and photometric standards of green/magenta color shift. I'm trying to use Resolve to test color biases between lenses; I want to know what standard filters I can use on a lens to help it more closely match a lens that I've chosen to be my standard.

I understand that Resolve's controls started out being display referred (unrelated to and disinterested in scene photography or even the input color space). However, as features such as the HDR palette become color space aware, I'd love Blackmagic Design to use a standard index on its Tint control.

Meanwhile, I intend to shoot some tests with CC filters, etc., to make my own correlation in Resolve.

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