M42 amd M43, Orion Nebula, with 92mm TMB Apo refractor and Borg 0.85x flattener/reducer for f/4.7, with Canon 20Da camera at ISO400 for stack of 4x 12 minutes, 4x4 minutes, 4x80 seconds and 4x20 seconds (for core). Bright area in upper layer selected, feathered, inverted selection, copied, the lower layer selected and Mask created, making a dark hole in the shape of the bright area for shorter exposure content to shine through.
The Orion Nebula complex consisting of M42, M43 and the reflection nebula area known as the Running Man Nebula, NGC 1973-5-7. NGC 1981 is the blue star cluster at top north edge. North is up, though in the sky from Australia where this was shot the object appeared upside down compared to this northern-centric view. This is a 3-exposure stack to preserve details in the bright core while bringing out the faint outlying parts. It is a stack of 4 x 1 minute + 4 x 5 minutes + 4 x 15 minutes, all at ISO 400 with the Canon 5D MkII (filter-modified) and Astro-Physics Traveler 105mm apo refractor at f/5.8 with the 6x7 field flattener. Images were aligned and masked in Photoshop CS6 using Refine Mask. An HDR stack did not work and produced odd artifacts. Images had to be manally stacked and masked. Shot from Timor Cottage, Coonabarabran, Australia, December 12/13, 2012.
An image of the Orion Nebula, M42 and M43, shot for demo purposes, taken through my standard (not Edge HD model) Celestron C9.25 inch SCT for 2300mm focal length at f/10. This was all unguided just for fun on a night I was shooting the 8-day-old Moon nearby above Orion. So this was taken in a bright moonlit sky and with light haze in the sky. This shows what is possible by stacking lots of very short though still well-exposed exposures even under less than ideal sky conditions, and with simple techniques. I used higher than normal ISOs for this to keep exposures very short to avoid trailing from the lack of guiding. However, it helps that this is the brightest nebula in the sky! The exposure blending retains the bright core and Trepezium stars while bringing what I could of the fainter tendrils that were visible in the moonlight and haze. TECHNICAL This is a stack of 32 x 6-second (!) exposures at ISO 6400, 24 x 6 seconds at ISO 3200, and 12 x 6-seconds at ISO 1600 for the core, all with the Sony a7III, and blended with luminosity masks. All alignments and stacking with Photoshop. So this did take a fair amount of skilled processing to make this look good. LENR dark frames were applied in camera to each image. This was with the Astro-Physics Mach One mount.
