@siracusa @atgw as someone brand new to astrophotography, I have a LOT of photos of pure black (lens cap on, at varying ISOs and exposure lengths = dark and bias frames to subtract sensor noise), and similar numbers of grey (my dimmed iPad screen resting atop my dew guard = flat frames to subtract dust in the optical train). John, I think it might be a hobby that fills the cockles of your nerd heart. Though I could see Marco going full send on it.