dark library in pixinsight

[brrttpaul]

I am redoing all my darks , flats, bias and going by the pix book. I have done my superbias and all my flats plus various lengths of darks, 30 secs 60 secs 120 secs 180 secs. (all at -25 degrees) and have been made into masters.  I am now on image calibration of flat frames and become a bit stuck, it says add flat files next enable master dark and master bias, master bias is ok but im stuck on master dark as I have 4 at different exp times. Do I have to repeat the process 4 times adding a different master dark? cant see anything in the book

[Shelster1973]

I do not use darks due to my CCD, but you would pick the dark sub length that is closest to the time of when you imaged.

Also (standing by to be corrected) there is not a huge point in building a library of flats as these are used to remove specific errors and 'blobs' that occur in the image train and these will invariably be different on each imaging session due to the slight changes in filter position, focuser position and the fact that those damn dust motes tend to flit around a bit too.  Plus you could have new affecting items in the image train after taking your flats which will not be removed when you use them.

Is a proper baffling and frustrating hobby this one of ours, but rewarding when you get to the end.

TL;DR - don't bother with a flat library, take new ones for each imaging session and pick a dark master that matches you light sub time.

[sloz1664]

Although I use Pixinsight for image processing, I rarely use it for calibration. I'm sure that it will pick the specific darks it requires. I know MaximDL does. I would try and add all the darks you require for your various exposure times and see what happens.

Steve

[brrttpaul]

I dont think PI does pick the specific darks, I have taken a load of darks in various exposures and made masters out of them, also a super bias.  Now heres where i get stuck , I have taken a load of flats (various filters LRGB) and wanted to make a master flat in each filter. But in PI it says add the super bias and the master dark to calibrate the flat, well which dark??? the 30 sec exp the 60 sec??? I am just doing this as a library and also to try and understand what goes on , ( Im going on the more I know how it works the easier to sort out problems). In DSS all I have to do is load the darks, flats etc and it makes the master, I just want to stick with PI and persevere with it

[daz]

1. Take all your Darks at the different exposures

2. Use ImageIntegration to produce the Master Dark for each exposure length. At this point you can decide to include the Master Bias - in which tick Enable Master Bias and add the file. If you don't you will need to include the Master Bias when you calibrate the lights.

 

The calibration of darks uses the Bias to scale the darks to match the exposure of the lights. You just need to decide at point in the process you calibrate the darks. I do mine when I do the lights.....

 

 

[daz]

5 minutes ago, brrttpaul said:

I dont think PI does pick the specific darks, I have taken a load of darks in various exposures and made masters out of them, also a super bias.  Now heres where i get stuck , I have taken a load of flats (various filters LRGB) and wanted to make a master flat in each filter. But in PI it says add the super bias and the master dark to calibrate the flat, well which dark??? the 30 sec exp the 60 sec??? I am just doing this as a library and also to try and understand what goes on , ( Im going on the more I know how it works the easier to sort out problems). In DSS all I have to do is load the darks, flats etc and it makes the master, I just want to stick with PI and persevere with it

Doesn't matter. The scaling for the flats is the same as for the lights.

[brrttpaul]

thanks I will have another go of it now

[daz]

It takes a little while to get your head around, but once it's in, it's really quite straightforward...

Especially when you learn about Process Icons and can create the necessary shortcuts with parameters set!

 

[brrttpaul]

it was just throwing me what dark i needed to do the flats