Pre-processing with DSLR: some questions

[mmerino]

I have followed several excellent pre-processing tutorials (and quite a few related threads in this Forum), namely:

* Jim Morse's PixInsight Cribsheet (recieved by email)
* Kayron Mercieca's Pre-Processing Tutorial (lightvortexastronomy.com)
* Trapped Photons Pre-Processing Tutorial (trappedphotons.com)

In some cases I have found different approaches for the same process and would like to know your opinions on (a) which option you use and why, and (b) which option is best suited for DSLR, if any.

These are the differences I found:

1- Bias, Darks, Flats and Lights Integration (in Pixel rejection I): enable or disable Clip High Range and Clip Low range? Are these important?
2- Bias and Darks Integration (Pixel rejection II): Sigma Low: 3 or 7? Sigma High: 4 or 7?
3- Darks Calibration: with SuperBias, or without it? (i.e. no bias calibration?)
4- Flat Calibration: calibrate with or without Master Dark? (can you scale a 300 sec. dark to calibrate a 1 s. Flat?).
5- Debayer: Before or after Cosmetic Correction?
6- Do you use "SubFrame Selector"? Does it have an important impact on integrated lights?
6- In Star Alignment: Use Distortion Correction, or not?

Thanks for your much appreciated input!

Miguel

[Warhen]

Hi Miguel, I'll provide my opinion-

1. Not critical. I leave clip high range deselected. See #2
2. I generally rock with default settings. I think you're mainly looking to avoid cosmic ray strikes in your masters.
3. Always use a bias frame. It allows darks to be scaled to lights and flats. It also allows the dark to be optimized even when integration times/temperatures of the calibration frames and the light frames 'match.' A Superbias will work well in lieu of the original master bias providing you got a good result when making the SB.
4. You shouldn't need a master flat dark. As above, the master dark will be scaled to the flats or skipped if not needed.
5. Always calibrate, including cosmetic correction before debayering. And of course, debayer before alignment.
6. I do use it. It lets me choose the highest SNR image as the reference image for ImageIntegration.
6. (again:>) It may slow things down a bit. If all data is from the same system and the stars are of good round quality, you shouldn't need it.