Comet NEOWISE (C/2020 F3) over the still waters this night of Crawling Lake in southern Alberta. The Big Dipper is at top. Even in this short exposure, the two tails — dust and ion — are visible. This was July 20, 2020. The blue ion tail is extending up into the Bowl of the Big Dipper, for some 20° in length. Very impressive! The main image content is a single untracked exposure of 20 seconds at f/2.2 and ISO 3200 with the 35mm Canon lens and Canon 6D MkII. The distant clouds, horizon, and water in the distance and in the immedate foregound without stars is from an average stack of 6 exposures, all at the above settings, to smooth noise. I shot this from Crawling Lake in southern Alberta on a near perfect night, though distant clouds are lit by yellow light pollution.
Comet NEOWISE (C/2020 F3) in a tracked close-up on July 20, 2020, showing the straight blue ion tail and the curving whitish-yellow dust tail. Even the ion tail was visible in binoculars and traceable out for 12° or so, or two 10x binocular fields. Here in the processed image it extends up into and beyond the Bowl of the Big Dipper, a distance of 20°. The curving dust tail extends about 15°. A bit of cyan colour is visible around the head of the comet. The bright galaxies M81 and M82, very tiny here, are at upper right. The two pairs of stars either side of the comet head are Tania (left) and Talitha (right), in pairs with the two stars each labeled Borealis and Australis. They form the feet of Ursa Major, but are also part of the asterism known as the Three Leaps of the Gazelle along with another pair to the west off frame at left. This is a median stack of six 1.5-minute successive exposures with the Canon EOS Ra at ISO 800 and Sigma 50mm lens at f/2.8, on the iOptron SkyGuider Pro tracker but unguided. Stacked and aligned automatically in Photoshop with the Scripts>Statistics function. Applications of Curves brings out the fainter tails without blowing out the bright head. I applied extensive sets of gradient masks to help remove the sky gradients toward the bottom (horizon). However, inevtiably some sky gradient colours remain. An application of ON1 Dynamic Constrast and a high pass filter helped bring out the ion tail details and subtle banding structure in the dust tail. Other than that I did not apply any local adjustments to the ion tail to accentuate its brightness relative to the dust tail. But as always, the long exposure of a camera reveals more than the eye can see. I shot this from Crawling Lake in southern Alberta on a near perfect night, though some light cloud or possible airglow still discolours the sky.
