Tutorial for Equalizing Backgrounds in Pixinsight Using Linear Fit

In this video for amateur astronomers newer to Pixinsight, I present a brief overview of using Linear Fit in Pixinsight to equalize backgrounds before channel combination. Towards the end I also show my final processed image of an LRGB imaging session on the California Nebula. Enjoy!
Here's some equipment I'm using for my setup:
Note: I am an amazon affiliate. If you follow any of the amazon links and make a purchase, it helps support my channel.
William Optics RedCat 61 WIFD f/4.9 Petzval Refractor Telescope
amzn.to/48bDmeI
Sky-Watcher EvoStar 100 APO Doublet Refractor Telescope
amzn.to/3PWW0gN
ZWO ASI183MC 20 Megapixel USB3.0 Color Astronomy Camera for Astrophotography
amzn.to/3CDJVtH
iOptron GEM28 Mount - Head with iPolar in Hard Case
amzn.to/3PR7WAJ
ZWO M48 to M48 Extender / Spacer Ring with 16.5mm Extension # ZWO-M48-EXT16.5 (used to obtain precise back focus with field flattener)
agenaastro.com...
ZWO Filter Drawer with M42 & M48 Threads - For 2" Mounted Filters # FD-M42
agenaastro.com...
2" Baader Neodymium Moon & Skyglow Filter with IR Cut
amzn.to/3sI9BiH
Optolong 2" L-Enhance Dual Narrowband Light Pollution Filter (H-Alpha and H-Beta/O-III)
amzn.to/3fnuCfB
This eyepiece is awesome for visual astronomy with its wide field of view.
Alpine Astronomical Baader 76° Morpheus 17.5mm Eyepiece (1.25"/2")
www.bhphotovid...
This is a very well made barlow lens I've been using for visual astronomy. I found thought that this doesn't seem very compatible for astrophotography for my setup unless using the diagonal (only way to get camera focus).
Celestron 93436 Luminous 2-Inch 2.5x Barlow Lens (Silver)
amzn.to/3KsfloY
This is a must have for astrophotography purposes.
Sky-Watcher S20201 Reducer / Corrector
www.bhphotovid...
Astromania M48X0.75 (2" Filter) Female to M42X0.75 T / T2 Male Thread Telescope Adapter (to achieve back focus with reducer/corrector)
amzn.to/3KueNid
Alstar Astronomical 2"/M48-extension Tube Kit for Cameras and eyepieces - Length 5mm 8mm 10mm 20mm 30mm - M48x0.75 on Both Sides (adapter to use with tubes for achieving back focus with reducer/corrector)
amzn.to/3ReIyps
SVBONY Bahtinov Mask, Aluminum Alloy Bahtinov Focusing Mask, 85-120mm Caliber Fixed Diameter 80-135mm
amzn.to/3RkVp9A
I find this lightweight cart handy for hauling in/out a stack of organizer boxes and the mount case.
Leeyoung Folding Hand Truck and Dolly,309 lb Capacity Aluminum Portable Cart with Telescoping Handle and PP+EVA Wheels
amzn.to/3KwAFcJ
Some gear for cleaning purposes:
UES Air Blower Dust Blaster for Digital, DSLR, SLR Cameras Sensor Lens Cleaning, Rubber Bulb Air Pump Dust Blower Cleaner - Black
amzn.to/3e4qUXc
UES APSC-16 DSLR and Mirrorless Digital Camera Sensor Cleaning Kits for APS-C Type CMOS and CCD Sensors (14pcs APS C Sensor Cleaning Swabs and 15ml Sensor Cleaner)
amzn.to/3cw0NYW
UES Lint Free Microfiber Cleaning Cloth for Lens, Eye Glasses, LED (8 Packs - 15cm x 15cm)
amzn.to/3Av4eHa
These are great for making sure you don't have any dust or dirty spots on your CMOS of your camera.
Beileshi Watch Repair Magnifier Loupe Jeweler Magnifying Glasses Tool Set with LED Light with 8 Interchangeable Lens-2.5X 4X 6X 8X 10x 15x 20x 25x
amzn.to/3Kwx26J
If you have to transfer images/files from your laptop to another computer for further processing, this external drive is very fast compared to something like a thumb drive.
SAMSUNG T7 1TB, Portable SSD, up to 1050MB/s, USB 3.2 Gen2, External Solid State Drive (MU-PC1T0H/AM), Blue
amzn.to/3PZ9o41
To avoid unrolling and rolling up power cables for each imaging session or setup where there's no outlet to connect to,, this is very convenient.
Jackery Portable Power Station Explorer 300, 293Wh Backup Lithium Battery, 110V/300W Pure Sine Wave AC Outlet
amzn.to/3KybHK7
If you want to share your astro images so I can feature them in a future video, send them to my email:
[e-mail]
Dehancer set me up as an affiliate. If you want to buy the desktop application instead of the iPad/iPhone app and use the following discount code, you will save 10% and I will also earn a small commission:
Dehancer Discount Code for a 10% Discount: DEHANCER-MAJ
Dehancer website: Dehancer.com

[@AmatureAstronomer]

Interesting.

[@marksastrojourney]

isn’t it though?

[@miguelo65]

Hi Mark, I never used Linear Fit in my astrophoto proccesing before, but this in a good tip. Thanks

[@marksastrojourney]

Always another technique or tool to try out!

[@miguelo65]

With your new monochrome camera, you find new challenges ,I am looking forward to you telling your experience regarding color ZWO 183

[@marksastrojourney]

Hi Miguelo, these are my thoughts. For the zwo monochrome camera, 1) image acquisition is more involved as I'm lately mostly interested in emission Nebula. This implies using Ha, Oiii and Sir filters. Longer exposures also seem to be more necessary for these narrowband filters. 2) processing is more prone to challenges. For example, if you get a disproportionately greater quantity of sub frames for one filter versus the others, you don't have a balanced set of data to process. 3) it takes me much longer to process LRGB or SHO due to the separate processing of RGB versus Luminance. Sometimes, Ha data alone can serve as the Luminance. Other times, it seems like a synthetic luminance must be made from Ha, Oiii and Sii. 4) sometimes it's hard to get a sense of how good the RGB and Luminance processing went until you combine them using LRGB Combination. If it didn't go as well as you thought, then you might taking a few steps backwards to redo something.
Regarding the zwo 183MC (non cooled). Something I plan to try is pairing it with my RedCat 61 telescope. However, it always has some amp glow that cannot be removed entirely with darks. This somewhat limits me to shorter exposures.
On another note, for the last month or so I've lost valuable time. I had switched over to Pixinsight for my post processing. I was also using the RC Astro tools. After some Pixinsight update came out, the RC Astro tools stopped working properly. I tried all kinds of uninstall/reinstall/updates, etc. I posted the problem to RC Astro and they basically said it must a problem with my installation and suggested I uninstall nd reinstall everything.
As it turns out, I discovered an online chat thread where another person had similar issues. It's due to the GPU on my IMac evidently. As soon as I saw their resolution and applied it, the issue was resolved. Basically, the AI used by RC Astro was upgraded. The newer version doesn't play well if you have an older IMac with the GPU I have.
But all these challenges are part of the hobby and I guess what makes it rewarding.
Clear skies!