Hi <
>,
I jabe some basic questions that I would need answering before trying to get to the bottom of your issues:
Up until now I have been happily processing . . .
What do you mean by this - processing inside PixInsight, or processing with some external software?
. . . my bias, dark, flat and light images all as RGB
First question - presumably you are letting the camera produce the RGB image from its own 'internal' RAW grey-scale data obtained from the imagiing sensor?
Second question - are you using Dark frames exposed for the same lemgth of time as for your Lights?
Third question - are you using FlatDark frames exposed for the same lemgth of time as for your Flats?
Fourth question (really more of a statement) - obviously, using a DSLR means you have very poor control of the thermal behaviour of the camera electronics
using (the) PURE RAW settings for DSLR RAW images
Yes - by doing this, you
should be getting the 'pure' data, as obtained direct from the camera sensor itself, with
no in-camera processing whatsoever. Any processing of the image by the camera software must, unfortunately, be considered as '
black magic
' - simply because the process is not publicised by the DSLR vendor. Given the opportunity, PixInsight always prefers to start yhe calibration process with RAW data.
no success at all in producing a master flat
Well a couple of things might be working against you here. First, as already menrioned, are you calibrating the Flat with an appropriate MasterFlatDark (as opposed to your MasterLightDark), and associated with this then mas to be the issue of even needing MasterBias frames at all (they are only needed if your exposure times for Lights and Darks - or Flats and FlatDarks - differ).
But, perhaps more importantly is what the camera internal software is going to do when you ask it to take images with very low ADU vaues and to then process these, internally, from a CFA-based greyscale format into a deBayered RGB format. It may well be a process that the vendor gave no consideration for, and so the internal software just has to 'do its best' - applying some arbitrary set of rules in the hope that the results will be acceptable and, more importantly, repeatable between calibration frame types. It is almost certain that the reslts will be neither acceptable, nor repeatable.
Can anyone shed any light on what I'm doing wrong?
Probably nothing, but perhaps everything
So much depends on those critical steps of image acquisition - where detailed information presented for analysis and critique is vital. Presenting PixInsight with detailed image data sets for calibration is, fundamentally, the single most important step that you can take.
Hope this helps.
