Colorchecker passport and the DNG profile editor

Question

I finally got around to getting a Colorchecker passport to use with the DNG profile editor.
I was secretly hoping I could save time by shooting the chart on location and make an instant profile out of that - then the colors would be at least "close ballpark" so I would just have to apply white balance and then move on to more specific adjustments. But of course it wasn't that easy, it still takes a fair bit of color tweaking to get right in most circumstances.
So I'm wondering if my energy would be better spent trying to perfect one good dual illuminant general profile. For this I would use 3000 K tungsten at one end and 5500 K studio flash at the other. Or would it be better to use overcast daylight? In either case it's obviously important to ensure the chart is absolutely evenly lit.
And then I should probably have a separate profile for fluorescent tubes.
I'm curious what other people's experiences with the colorchecker/DNG profile editor are? How are you using it?

Answer 1

The color profile changes with the lighting, so a profile that was computed for daylight won’t be right for tungsten or fluorescent.  Keep in mind that a custom camera profile is the set of corrections on top of an existing Adobe profile that the DNG has assigned to it, perhaps Adobe Standard, and all Adobe profiles are dual-illuminant profiles, so it makes sense you’d want to also create a dual-illuminant profile for general purpose use that has the same two lighting scenarios as Adobe used:  2850K and 6500K.  The 6500K is the tricky one because full sun is warmer, closer to 5000K, and you need the right amount of haze to create 6500K sunlight, unless you are using standard D65 bulbs, indoors, which is likely what Adobe does.
I use a dual-illuminant profile for general purpose use, but since the WB-Tint values of both the tungsten and daylight ends are close to zero, lighting that has a tint not close to zero needs a separate profile.  The common example is the greenish light from fluorescents, and I have several single-illuminant profiles for various artificial lighting scenarios with WB-Tint values that are relatively non-zero.  I also have ones for very red sunsets and very blue twilight.  If I had studio lighting I’d make a profile for that.  Sometimes I make a custom profile for a church or other venue that has significant non-neutral walls or ceilings, or where sunlight through the stained-glass windows shining on the walls are giving a significant color-cast including a non-zero tint value to the lighting.  If you know you’ll be doing some shots near a large amount of tall, green vegetation then a custom color profile can correct for the green tinge to the ambient lighting coming down from above mixing in with the sunlight. 
Adding to the suggestion about wearing neutral clothing, I’d argue for dark neutral clothing because something lighter clothing will reflect environmental colors (sunlit vegetation or brick walls, etc, outdoors) and not be neutral. 
Besides non-neutral clothing, try to avoid areas that have green grass or tree leaves or brick buildings that also color the light and reflect off the colorchecker.   For the sunlit shots, I put my colorchecker face up on the sidewalk or parking lot, to avoid coloration from the grass and far away from trees or buildings especially in the direction I’m pointing the camera, so the only lighting is direct sun and ambient blue-sky, possibly diffused by hazy clouds.  I point the camera down at the colorchecker, at a 45-degree angle and at a compass direction and not directly toward the sun, nor directly away from the sun.  I try to shoot the target that is face up on the ground perhaps at a 90-degree angle from the sun to minimize any residual glare from the colorchecker’s slightly non-matte surface.  Obviously directly away from the sun, the color-checker will have my shadow on it or I will be blocking the light from the sky near the sun.
I use the same sort of process for the tungsten end, choosing a room with neutral walls and put the target relatively flat on the floor facing up, perhaps tipped up somewhat toward the light, but not so much as to have any glare from the lighting, either, in other words, not with the lighting directly behind the camera, but somewhat over to the side.