I have a curious finding. It is the calculation of identical (to the third decimal place) TCs (Tbv and Tv_bv) for the same camera and filters, in one instance imaging through a 200mm Canon camera lens, and in the other through an 8" SCT.
Useful to know for my equipment, but my understanding was that TCs should be calculated independently for each entire imaging train (because they may differ).
Roy:
My first observation is that my average coeffs from 3 nights are typically similar to ± a few percent (2nd decimal point). If the skies are good while imaging the standard fields, I may achieve coefficients that are similar in the 3rd decimal point but not identical. So, I find it surprising that you achieved that level of precision in even one system let alone two different systems.
Clearly the filter is the key element in transformation but the entire optical system may affect transmission of light of different wavelengths so it is appropriate to measure the coeffs of the whole system.
I guess I would consider you amazingly lucky! Can you share some mutli-night results?
Ken
Must apologize. Calculation error. The values for Tbv were not identical, but the values for Tv_bv were. Just a statistical fluke.
Ken, there are no multinight data - I haven’t had enough clear nights recently to repeat the observations.