I shoot my astrophotography images in RAW with daylight 5300k white balance. I don’t correct WB in post.
Now I have a light pollution filter which introduces a strong blue-violet cast. I am looking at a rigorous way to compensate for the LP filter in PP and restore the 5300k look.
This is why I came up with:
1)shoot a colorchecker card at noon sunshine with the filter on and in-camera WB set to 5300k
2)open the RAW in RT and pick the WB drop tool on the white patch- that should adjust WB and give me “corrected” temp and tint values.
3) apply those temp and tint to pictures when I shoot with filter on and 5300k set in camera
The white balance setting in your camera should have no effect on the captured raw image.
But you do.
Considering that the light pollution filter passes through a narrow band of the spectrum and your camera further has a Bayer filter, practice and experimentation are needed.
Other things to try:
Shoot the moon through the filter to white-balance your camera, when the moon is near zenith to avoid pollution near the horizon. The moon has a neutral color and reflects sunlight, so hijack it as your personal gray card.
Create a DCP input profile of your color target with the filter on during midday.
It might, or it might burp if shifts are too extreme. Sounds interesting-enough to give it a shot. If it works, and if daylight can be used as a standard to improve photos of light which came from across the galaxy, then it should lead to more accurate results.
This is one of those “experiment and see what works” situations. With my old Canon camera sometimes I’d use a magenta filter to even up the amount of light reaching the blue and red pixels on the sensor. Per the recommendations made by Iliah Borg at that point in time, I did make a target shot with the filter on the camera, and made a new camera input profile to use whenever I was using the magenta filter.
But for some reason even when using the magenta filter, I ended up preferring the colors from my regular “no filter when making the target shot” camera input profile, and setting the white balance using a neutral object. Or in your specific case, put the filter on the camera and white balance on a neutral object in direct morning sunlight on a “clear blue sky” day to acquire your daylight white balance to use for your night shots.
It’s definitely worth making custom “with filter” ICC and DCP input profiles. But compare using these profiles to just using a custom white balance and your normal camera input profile.
Thanks for the input. Yes I believe I will try both setup and see which one works better for me. As soon as I have some results and test shots I’ll post here.