Building A Barn Door Tracker For Astronomical Photography

That’s a pretty amazing image to catch peering out from your back balcony. The rig used to record such a gem is seen on the right. It’s called a Barn Door tracker and was built by [DCH972]. Details for this build are scattered all over the place, there’s a video (also found below), another album of some of the best images, and plenty of background info in the Reddit thread.

This design is also know as a Haig or Scotch mount. While we’re dropping links all over the place check out the Wikipedia page on the topic. The point of the system is to move the camera in such a way so that the stars appear to hold in the same place even though the earth is moving. There’s an ATmega32u4 breakout board riding on top of the breadboard. It’s doing some pretty heavy math in order to calculate the stepper motor timing. That’s because the mount is like a photo album, hinged at one side and opened on the other by a ball screw. This linear actuation needs to be meshed with the change in angle of the mounting platform, and finally it needs to sync with the movement of the earth. But once a series of images is captured correctly they can be processed into the composite photograph shown above.

If missed that SDR galactic rotation detector from last May you should find it equally compelling.

[Thanks Nathan]

13 thoughts on “Building A Barn Door Tracker For Astronomical Photography

    1. There are a bunch of astronomy photo processing tools that will readily remove the skyglow… You also take a series of defocused “flats” and “darks” to calibrate the image and remove background noise… Its a cool process – check out forums for a ton of info on the topic..

    2. Hi there–I’m the guy that put this together (imagine my surprise checking my RSS feeds this morning…!). Just to clarify, the only images I captured in the light polluted area were starfields to check calibration. The images of galaxies and nebulae were taken about 1.5 hours north of LA (where the “balcony” pictures were taken) at a much darker site.

      1. k-30 with a da* 50-135? :)

        Have you tried the pentax GPS modual?, it uses the camera’s sensor stablisation to move the sensor in time with the earth roatation keeping the star’s in the same place.

        I know you will be limted to a smaller digree of movment/time frame but people have been getting great results from it.

      2. k-30 with da* 50-135 f2.8? :)

        Nice setup, I’ve never done astro photography but I was wondering if you tried the pentax gps unit? It allow’s you to use the sensor stablization to track the stars.

        I know it will allow less movment than your setup exspecualy at longer focal lengths but people have been getting great results from it and could be something worth while.

        1. I looked at the O-GPS1 for a while and thought about getting one (it does has its advantages in terms of portability and ease of use), but ultimately I wanted something that’d be a little more flexible/customizable and capable of longer exposures.

  1. Hi Very nice design.

    It will use less battery power and handle a heavier camera setup if you reverse the whole unit and run it in reverse — allowing the hinge to close, assisted by the weight of the camera — instead of using the motor to open the hinge. If your design allows for this modification, you might get longer battery life or longer imaging sessions, especially in cold conditions when these things matter more.

    B. Vietje
    Newbury, VT

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