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Saturn, M8, M20 & M21

astrophotography dslr planet dso star party tripod


Alen Koebel

Saturn, M8, M20 & M21

This is a stack of four 60-second images @ ISO 1600 taken with a Pentax K-3II DSLR on a tripod and a 200mm f/4 SMC Pentax-M lens @ f/5.6 on August 10, 2018 at the Starfest star party near Mount Forest, Ontario. Note the bright yellow "star," which is actually Saturn. The camera was mounted directly on the tripod; no external tracker was used. This is possible because the camera includes a feature called Astrotracer that functions as a tracker up to a certain amount of time that depends on the lens focal length. This was just a test; obviously more exposures would be needed to reduce noise and increase captured nebulosity. No CA reduction in software has been done and the image obviously could use that. And while the diffraction spikes on Saturn are pretty, next time I will avoid them by using a series of step-down rings to reduce the aperture to 37mm (f/5.4) instead of using the lens's own aperture control. Note that this image used no flats, darks or bias frames. Dithering between every frame occurred naturally because of the movement of the object between exposures, which was approximately recentered after the second exposure. Given the movement between frames the full APS-C frame has been cropped somewhat.

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