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In order to minimize noise in my data, I've gone the Tony Hallas way and started dithering between exposures. My setup is a simple one (EQ3 Pro with Pentax K20D, no guiding), and I try to keep everything as much standalone as possible, since I don't want to take my computer out in freezing cold or wet grass. Unfortunately this also means I have to do dithering by hand, i.e. pushing the Dec/RA buttons on the Synscan hand controller between exposures. Doing this for a few hours in a stretch at -10 C or colder, is definitely not my idea of having fun. So I started thinking of automating the dithering procedure. Searching the internet, I found no solutions for unguided dithering compatible with my setup, so I decided to build my own. The idea was quite simple: The RJ12 port of my Synscan hand controller controls the camera, working as an intervalometer. The Synscan mount controller has a guiding port, so all I had to do is find a way to send signals to the guider port in between exposures. So, I built a simple circuit around an Atmel ATtiny84 which takes the Synscan camera control as an input. It senses when an exposure ends and sends a signal to the guiding port. A counter keeps track of which command to send from a simple string: 214488222111444488..., where 2 means Dec+, 1 means RA+, 4 means Dec- and 8 means RA-. So here is a pictures of my solution. The ditherbox is the black box below the mount controller. It has three connections: input from the hand controller (RJ12), output to the camera (phono plug type) and output to the mount (ST4, RJ12) FYI, I put the code and a more detailed description on my Github page: https://github.com/wberlo/AutoDither I've tested it and it works like a charm. Unfortunately I have no images yet with this setup, because when I tested it, clouds moved in after just 5 exposures. I do have 20 dithered exposures of clouds.