I'm using a DSLR and backlight (tablet) to scan 4x5 color negatives. All the tips I've found online are really just hacks: invert the Tone Curve, then use the color eyedropper on the clear/orange negative to set a white balance, etc. The results are poor for two reasons: (1) the colors from the scanning light source are not even over the entire spectrum, and (2) the scheme doesn't address the low gamma of color negative. All these articles and videos adjust contrast/luminosity ad-hoc. I'd rather have an accurate place from which to start.
I'm thinking of creating a Camera Profile, perhaps a Dual-Illuminant one using a ColorChecker Passport for this purpose. Does anyone have any experience/knowledge about doing this for color negatives? Also, I'm wondering if profiles using a ColorChecker profile corrects for luminosity and gamma or just for color.
Here's my current scheme: (1) photograph the ColorChecker Passport in 4x5 color negative under "daylight" lighting. (2) Scan the negative with the DSLR. (3) Import into Lightroom and simply invert the Tone Curve. (3) Export as a TIFF or perhaps 32-bit image. (4) Re-import. (5) Create a color profile.
Is there a better way to do this? Is there something already built into Lightroom that makes this simpler or more accurate? Or is there an entirely different technique I'm missing? (One other idea I have is to open the scanned image in VueScan, which already knows how to deal with low-gamma color negatives and let it get me closer.)