This is the fairly bright emission nebula NGC 281 in Cassiopeia near the star Alpha Cassiopeiae, or Schedir, at right. NGC 281 is also known as the Pacman Nebula, an obviously modern name but quickly becoming dated! This is a stack of 8 x 8-minute exposures with no filter, blended with 5 x 12-minute exposures with an Astronomik CLS broadband nebula filter, all with the Canon EOS Ra, at 1600 for the unfiltered shots and ISO 2500 for the filterered shots due to the filter factor. All were through the venerable Astro-Physics Traveler 105mm apo refractor at f/6. And on the AP Mach1 mount. Clouds prevented more filtered shots. Guiding was with the new Lacerta MGEN3 stand-alone autoguider, using its function of also controlling the camera shutter and performing “dithering” to shift each image by a few pixels at random so thermal noise averages out when the images are stacked and aligned on the stars. For the test, I did not use Long Exposure Noise Reduction or any dark frames, to test the effectiveness of the dithering in averaging out the thernal nouse. It seemed to work fine! And the MGEN guided very accurately. In this case, all stacking and alignment was with Photoshop 2020. The Lacerta MGEN3 is made in Hungary and sold thru 365Astronomy in the U.K. where I bought it from.
The Pacman Nebula, NGC 281, in Cassiopeia, near the star Alpha Cass, aka Shedar, at right This is a stack of 10 x 6 minute exposures with the filter-modified Canon 5D MkII at ISO 800 through the TMB 92mm apo refractor at f/4.4 with the Borg. 0.85x field flattener/reducer. Taken from New Mexico, Nov 18, 2014.
The small emission nebula NGC 1491 in Perseus, with the large bright star cluster NGC 1528 at left. The field has other faint nebulosity throughout. This is a stack of 5 x 12 minute exposures with the TMB 92mm apo refractor and Borg 0.85x flattener/reducer for f/4.8 and filter-modified Canon 5D MkII at ISO 800. Taken from home Oct 9/10, 2013.
