Tuesday, 28 September 2021

New Season and Technique Updates

Testing and Rediscovering

Hello!  It's been a while 😏.  Very little has happened since March in my astronomy world, but with the return of darker evenings my mojo has been found and I'm now back at the helm of the good ship Astro.  I thought I would kick this post off with a couple of images which I have put together in the last couple of weeks.  As with many things, if you stop doing them for a period of time, you can get a bit rusty so this was a chance for me to get some practice in ahead of the coming Winter.
I've imaged two targets, the first of which is part of the Veil Nebula.  Shot over two evenings with around 3 hours of exposures, I didn't want to waste this trial data which I collected so I run it through my processing plans and come out with a reasonable effort to be honest.


I had a bit of fun with the colours in this one as I retaught myself the little nuances of PixInsight's PixelMath feature.

A week or so later, again over a period of a couple of nights, I gathered another set of trial data to play with.  This time, of the Iris Nebula.  Again, this is a target I have imaged before, and one which probably requires much more data to really start pulling the detail in the darker areas of the image.  Nevertheless, it gave me a great chance to run the whole process from start to finish and rediscover my processing workflows.



Technique Updates

Many moons ago, back in February 2019 I put this post together as I continued my journey of using PixInsight to process my astrophotography images.  It was intended to help anyone who wanted to get an idea of where I got my information from and how I like to process my information.  Since then, quite a few updates have been released to PixInsight, and I have also starting to use a quadband filter which opened up a whole new series of processing tools and techniques.  I decided that it was time for an update and so I have updated my documentation to take into account the updates to software and workflows.
At this point, I have also got to put a big shout out to GIMP, the opensource alternative to some of the more popular and hugely expensive image processing software like Photoshop.  I've found it so useful to help putting the finishing touches to my images, that I thought it's worth adding those final few steps I take before considering an image complete.  I always carry out the GIMP part of the process after all my PixInsight work is done.

Before you start...

Remember that some of the settings in these workflows are specific to the Altair Hypercam 183c and the focal length of my Altair Starwave refractor.  If you want to use these as guides, you may need to change some settings to reflect your gear.
The colours of the extracted layer during the background extraction steps could differ for you depending on your camera or filters.  That shouldn't matter, nor affect the image you continue to work on.
These really are best endeavour guides and documents.  I make no secret that I have watched, read and listened to many other astrophotographers much more accomplished than me and taken snippets of info and steps from their workflows to develop my own set of steps.  I really couldn't of got anywhere without the willingness of the astro-community to share their knowledge on how to achieve results.  I hope that this feeds back into the community and helps others a little.

Calibration Through to Stacking

This is the first update to my processing workflow.  You've been out imaging all night. You've got all your light frames, your darks and your lights.  This document has been updated to include some minor changes and screen shots and goes through how I stack and calibrate that data to produce an image which can then be taken forward for processing.

WBPP

Sometimes, no matter how hard I have tried, I have struggled to get PixInsight to calibrate and stack my data.  It can turn into a minefield, trying to track down which options in the workflow to tweak, miss out or substitute for something else.  At times like this, I have turned to a script in PixInsight called WBPP.  It's kind of a one stop shop for all the calibration steps you need to put together an image which you can then carry forward to the remainder of the processing stages.  Some people use it all the time for all their images.  Others, like me, only use it occasionally.  Either way, I thought it would be useful to include the workflow I use in this document if I go down this route.  Something to be aware of though, these scripts are updated quite regularly, so appearance can change and the screenshots will be outdated.  But, the principle of it will generally stay the same, so with a bit of a rummage around you can still get it working quite well.

Post Stacking Processing

Depending on what filters I have used to collect all my data during the imaging run depends on which processing workflow I use to work on producing my image.  This document goes through a typical workflow I go through if I have been using either no filters, or something like a light pollution filter.

Post Stacking Processing - Quadband

My most recent addition to the astro hardware cupboard was been an Altair Quadband Filter for use with CMOS cameras.  This, in combination with my Altair 183c Hypercam has kind of revolutionised my image processing and brought me on a step when I started learning more about it over the last couple of years.  I was able to add in a different set of techniques to my workflow which I have put into this document.

Preparing for HiRes Printing

At the end of all this, hopefully you have an image you are pleased with.  Some people decide they are so pleased with the image that they want to print it our.  This is a whole other ball game and you can quickly disappear down into a rabbit hole of different colour profiles, printer types, resolution etc.  Admittedly, these aren't steps I do very often, but I put a couple of pointers in this document on how to perform some initial steps on getting your image ready to print using some features in GIMP

So, there you go.  The end of another post which I hope is full of information and resource that others might find of interest.  Of course, comments are always welcome (but moderated before being posted) and I'm always interested to hear from others on things they might do different, what works for them and what doesn't work.
Thanks for your time and clear skies!

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