AstroPi3 Part 1 - Raspberry Pi 3 as a autoguider computer
AstroPi3 Part 2 - Creating the Installation Image
AstroPi3 Part 3 - Installing Ubuntu Mate
AstroPi3 Part 4 - Installing AstroPI3
AstroPi3 Part 5 - PhD2 Configuration
AstroPi3 Part 6 - DSLR/Guide Camera Setup and Control
AstroPi3 Part 7 - Raspberry Control with Tablet/Cell
AstroPi3 Appendix A - Index of Possible Problems, Causes and Solutions


1. Know the resolution of your DSLR camera and the Pixel Pitch This information can be found on this site:

KStars - Ekos

KStars is a free opensource application for astronomy, like Stellarium or SkySafari. This software includes a module called Ekos, which allows us to control cameras for astrophotography. The interesting thing about these applications is that you can use the same Ekos as a guide system and intervalometer for taking pictures. It has options to save the images either in the same camera or in a different location, such as a hard drive or external SD card, as well as assigning a custom image file name, configuration of darks, bias calibration shots, etc. etc.

Honestly speaking, in my experience with opensource/linux, it is often the case that these applications are not as intuitive for an ordinary user, especially when we are learning to use it or worse, when we are installing it for the first time. For those reasons, I made this tutorial hoping it will be helpful to you.

Ekos-KStars configuration, first time execution

  1. Double click on the KStars icon.
  2. The first-time-use wizard will start. Click on Next.

  3. On the next screen select your location in the list and click Next
  4. Optional: A screen will then be displayed to download additional information such as stereo catalogues (abel, caldwell, etc). It is not necessary to do so at this time, so click on the OK button.

  5. Select the Tools-> Ekos menu

  6. This will launch the Ekos wizard for new profile creation, since this is the first time it is used. In this profile is where we save information and settings of the computer we will use. Click Next to continue.

  7. Write a descriptive name for your profile and press the button. Create profile & select devices.

  8. Select the list of devices you will control. In this example, we will use two: a Canon t4i camera for photo acquisition and a ZWO ASI 120mm-S for guidance. Then click on Save.
  9. Next, the Indi control panel will be displayed, which is where we will configure the options of our devices.
    Note: It is important to note a odd red error message in the background of the screen.

    This is due to the fact that there is no configuration file for that device, since it is its first use. What we must do is simply go to the Options tab of that device and we can see how there is a red circle next to the Configuration label, which indicates that there is no file.
    Press the Save button. The circle will turn green. The next time you open the screen, the red error message in the background will not be shown.

    Note: This must be done individually for each device, only the first time it is used with Ekos.

  10. Click on the DSLR tab, in this case the Canon DSLR EOS 650D. Then click on the Image settings tab.
  11. Click on the Native and SD Card buttons. We do this to tell Ekos that we want the image to be stored in the camera in the format selected by the camera, and not on the computer.

  12. Click on the Options tab and then on Save to save the DSLR settings. The red circle will turn green indicating that the information has been saved correctly.

  13. Click on the Close button in the lower right corner of the screen to close the Indi control panel. All this process is done only once, at the time of first use of a device with Ekos.

    Ekos Initialization

  14. The first thing we must do every time we do an astrophotography session is to initiate communication with our devices. To do this, we simply click on the button indicated in the image below to initialize the Indi Server.

    Si la conexión fue exitosa y las cámaras se conectaron automáticamente, verás aparecer las siguientes pestañas adicionales; de lo contrario, presiona adicionalmente el botón Connect.

  15. If the connection was successful and the cameras connected automatically, you will see the following additional tabs appear; otherwise, additionally press the Connect button.

    Verifying the guide camera connection

  16. Click on the guide tab, then click on the Loop button. An image of what the camera is capturing should be displayed on the screen.

    Photo acquisition with the DSLR: using Ekos as an intervalometer

  17. Click on the photo acquisition tab.
  18. Before we start, we will make sure that the camera is well connected and that we can control it with the Ekos. To do this, simply click on the Preview button.

    A viewer with the image will be displayed on your screen

  19. Following we will create what for Ekos is a " job ", meaning a photo acquisition sequence. Ekos allows us to create several preconfigured sequences, and add it to a sequence row.
    In the acquisition screen, configure the following parameters:
    - Exposure.
    - Count ( number of shots to be taken )
    - Delay (time between each shot)
    - ISO ( ISO of your preference )
    - Format: select Native
  20. Click on the "+" button to create the sequence and add it to the list
  21. Click on the sequence (the row that we just added) and then on the "Start" button at the bottom of the screen to start the photo capture.

  22. There is one issue with this application, and that is that during the execution of a capture sequence, every time you take a shot, it opens the image viewer showing the shot you just took. This can be a bit annoying.

  23. To disable the appearance of the Image Viewer every time you run a shot, do the following: click on the Options button on the same screen or click on the menu Settings->Configure KStars.

  24. On the Configure - KStars screen, click on the Ekos icon and leave the DSLR Image Viewer option unchecked. Then click on the Apply button and then on the Ok button. The image viewer will be disabled.

    Note: The option to disable the image viewer is new, and is available from the version released in December 2018.


Congratulations !!!

You have successfully configured your Raspberry Pi 3 for image guidance and acquisition. We will continue with the final stage which is controlling the Raspberry with a tablet or a cell phone.