This is a portrait of the main nebulosity in Orion in his Sword, including: the Orion Nebula itself (at centre), aka Messiers 42 and 43, and the Running Man Nebula above (aka NGC 1973-5-7). The bright blue star cluster NGC 1981 shines above the Running Man. The subtle reflection nebula NGC 1999 is below M42 but a bit lost amid the other faint and dusty nebulosity. The field of view is 4° by 2.7°. This is a stack of 11 x 6-minute exposures with an Askar FRA500 astrograph (500mm focal length at f/5.5), and stock Canon R6 camera at ISO 800. The camera was not modified and no filters were employed here. I did not take short exposures for the core of the bright Orion Nebula. Some light haze added star glows. Nebulosity is brought out in Photoshop using successive curves with luminosity masks generated by Lumenzia, and with applications of the Nebula Filter action from the PhotoKemi StarTools action set, and Enhance DSO from the Astronomy Tools action set. All alignment and layering was in Photoshop. Taken from home January 26, 2022. Autoguided and dithered with the MGEN3 guider, with LENR dark frame subtraction also applied to each frame in camera to eliminate the edge amp glow the R6 exhibits. It was about -5° C this night.
The Orion Nebula, M42, with its companion nebula M43 to the north, and the blue Running Man Nebula at top (aka NGC 1975), all in a clear but moonlit sky, illuminated by a first quarter Moon, making the sky blue. So this can’t be a very deep image, but it shows the main features visible in a large telescope. The loose open cluster, NGC 1981, is at top — I should have framed this scene a little more north to better include the cluster. This is a blend, using luminosity masks, of three sets of exposures: 8 x 8 minutes for the main image content + 4 x 2 minutes for a mid-level exposure for the core area + 1 x 30-second for the Trapezium area right at the core. This sort of “high dynamic range” blending is necessary for M42 as it contains such a range of brightness that no single exposure can record it all. However, I did not use HDR methods to do the blending, but luminosity masks which are easy to make with one click in Photoshop — Command/Control click on the RGB Channel image — and they allow far greater control of the blending. This sort of exposure blending is needed because while your telescope-aided eye can see the faintest tendrils and the bright quadruple star system, the Trapezium, at the centre with no problem, cameras cannot. At least not in a single exposure. All were with the Astro-Physics Traveler apo refractor at f/6 with the Hotech field flattener and Nikon D750 (not modified) at ISO 200!
The Orion Nebula, aka Messier 42, at centre, with the blue Running Man Nebula (NGC 1973-5-7) above it. The smaller nebula attached to the top edge of M42 is M43. The blue star cluster at top above the Running Man is NGC 1981; the loose star cluster below M42 is NGC 1980. This is a stack of 8 x 5-minute exposures with the Canon EOS Ra mirrorless camera at ISO 800 unfiltered, blended with a stack of 6 x 8-minute exposures at ISO 1600 but through the dual-band Optolong L-Enhance filter that records the faint red nebulosity very well. Blending and masking the filtered with the unfiltered shots allows the faint red nebulosity to come through while retaining the blues, magentas and even subtle greens of the bright nebulosity and the blue of the hot stars as recorded by the “white-light” images. These two sets of long exposures are blended using luminosity masks with a set of 6 x 60-second exposures and 4 x 30-second exposures, both at ISO 400, for recording the bright core of M42 with its Trapezium stars that would otherwise be overexposed into a bright mass with only long exposures. The short exposures were all unfiltered. I applied a high-pass sharpening filter to snap up contrast in the dark lanes. All were through the SharpStar HNT150 Hyperbolic Newtonian Astrograph at its native fast focal ratio of f/2.8. for a focal length of 420mm. Taken from home January 28, 2020. All stacked, aligned and blended in Photoshop 2020. PS’s Auto-Align function aligned all 24 images in one fell swoop in less than a minute.
