The Leo Triplet - M66 Group
The Leo Triplet (also known as the M66 Group) is a small group of galaxies about 35 million light-years away in the constellation Leo. This galaxy group consists of the spiral galaxies M65, M66, and NGC 3628.

This group is close to the end of what my relatively wide FoV Esprit 100ED can capture and still present a reasonable size for the object in the post processed image.

I'm providing two version in this posting.  One will be the full size image as provided by my Esprit100ED/ASI2600MC-P.  The second image (the "Final" version) will be cropped to enlarge/insure the The Leo Triplet is the center of attention in the image.

The final image is composed of two set of image/filter setups:
Optolong LPro for broadband:  67x120sec
Antlia ALP Duo NB: 60x180sec.

The stacking/post processing was completed in PixInsight.  The two sets of images were stacked, drizzled to reduce star pixelization/smooth the background.  Then they were cropped to match and a matching dynamic background extraction was performed.  The two images were then combined via Pixel Math, denoised, and a permanent stretch applied.

The ALP NB version was also given a rough denoise/stretch, then the stars were removed and the Ha (red) channel was extracted and tweaked to enhance contrast.

The combo image was also processed through the Star Exterminator add-on to PixInsight to create separate Star and Starless images.  Color saturation was increased in the Stars version.  Curves were applied to the Starless version to enhance the image and improve color saturation.  The Ha channel was then added using a PixelMath script to enhance the Ha details in the galaxy.  The Star and Starless versions were then combined in a simple Pixel Math addition.

A final full and cropped version were creaated and jpeg versions were saved and sent to PhotoShop for tweaking.  In PhotoShop the Topaz AI Denoise was used for to apply some post processing noise reduction/smoothing and the curves were slightly tweaked to improve the image  contrast/black level.

Having looked at this image set previously and not being particularly happy with the initial results, I had set it aside.  In the interim I discovered some issues with my calibration files and spent a couple of days rebuilding my dark and flats/dark flats libraries.  I also discovered in that work process that the issue of zero/negative value pixels does occur with today's modern quiet CMOS astro cameras, not just monochrome NB as popular wisdom suggests.  It is particularly prevalent when using OSC NB filters.  Once I found and addressed the issue through pedestal adjustments in PixInsight, the quality of the stacked images/post processing results improved significantly.  Never take your calibration files for granted - they are the foundation that everything that follows rests on.