Better to remain silent and be thought a fool than to speak and to remove all doubt.
And, here goes anyway.
One interesting observation when using the grey card to conduct an in-camera white balance versus using the white side of an x-rite color checker video card...
I set up a card holder stand straight on into full sun on a clear day. The URSA 12K was tripod mounted and framed up so that the white card and grey card both fully filled the WB sample area (no black frame on the white card and no white frame on the grey).
I activated the WB on the white card, hit record, and then swapped the white card with the grey card.
Next, I activated the WB on the grey card, hit record, and then swapped the grey card with the white card.
Interestingly (to me, anyway), WB on the white card provided a perfectly flat, white line (eg. aligned RGB levels) in the RGB parade scope, but the grey card RGB levels under that WB setting were quite obviously not aligned and showed distinctly different red, green, and blue levels.
Conversely, a WB on the grey card resulted in a perfectly flat, white line in the grey area (with flat lines above and below the grey line for the +/- 5% dots) on the scope, but the white card RGB levels were no longer aligned.
Also, the color balance (*K) and tint values changed quite a bit between the above two auto WB actuations. Visually though, the two shots looked pretty much the same on the color chart.
Bear in mind that until purchasing the 12K, I've really only used non-raw cameras - typically broadcast models. So, I'm expecting most of you will not be surprised with these results. I freely, if a little embarrassedly, admit to being a relative novice in RAW workflow. Please just allow for my learning opportunity and voicing this in my effort to better understand things. From my earliest tube cameras to my last HPX P2HD model and even my Phantom, my mental process has always been that the white balance on a white card was most important to get rolling and that you let everything else fall as it may from there. Having this grey card is forcing me to question that assumption and just possibly learn something new. Who knows what else I might be able to unlearn?
What I think my take-away from earlier discussions in this thread and elsewhere and this rudimentary experiment of mine should be is that using this particular grey card as my balance reference ensures that the middle grey / skin tones are the most technically accurate (which John rightly comments should only be your starting point). You can fix the highlights later. However, just using a white card for your WB setting will give you balanced highlights at the (likely) expense of properly balanced skin tones and possibly everything else. AND, the even better option is to simply shoot both the grey card and white card (and probably the color chart) to provide a starting reference for middle grey and highlights in post.
The majority of what I do probably doesn't require this level of workflow. And yet, I want to learn, grow, and understand those things that I don't know so that I'll be a better service provider for the clients I have.
#FoolDoubtRemoved
URSA 12K, DR Studio 17, SmartView 4K, SmartScope Duo 4K, VideoAssist 4K, Decklink 4K Extreme, Hyperdeck Shuttle II, MacPro (cylinder) 10.15.7, 128GB RAM, 12-core, D500, 12TB RAID5 USB, 36TB RAID5 mini-SAS