Astrophotography Equipment: System Diagram

Once you have your components assembled and connected together in a way that works for you, it is a very good idea to draw some diagrams to record the design.

These will be invaluable when you are assembling your setup, especially while tired and cold. If you have a permanent setup, diagrams are still very valuable, to help you debug why some component has mysteriously stopped working, or remember where all the wires went after you temporarily disconnect something.

There is no reason to obsess over standard diagram notations (although such things exist if you care to research them). Just use any simple drawing tool (computer or ruler) and draw some block diagrams.

I find two views useful:

Logical Diagram

A Logical Diagram giving a high-level, conceptual view of the components

A Logical Diagram of your system records a high-level view of what talks to what, ignoring certain details that are unimportant for a basic understanding.

For example, this diagram indicates that the camera, filter wheel, and guide camera are directly controlled by Maxim DL, but it leaves out detail such as which devices have power supplies, and whether the connections go through USB hubs or serial cables. It also clearly shows an important point, that the mount is controlled by both Maxim and TheSkyX, through an intermediate ASCOM hub.

Physical (Wiring) Diagram

A physical diagram recording where the wires go

A Physical View of the same system provides more detail on where physical components such as wires, cables, and power supplies go.

This diagram, for example, indicates

  • that the mount and focuser are controlled by serial cables while the other devices are USB, driven by a hub;
  • which devices have their own power supplies;
  • that a special “autoguider cable” runs from the guide camera to the mount.

If you take the time to draw several different system diagrams of your setup, you will find it pays back many times.

It’s also cool-looking and will impress your friends when they visit your observatory.


These example diagrams are a previous version of my own setup, for CCD imaging of deep sky objects. I’ve simplified my own setup since, but used these older diagrams to show how they help clarify complexity. If you are using a DSLR, or a point-and-shoot camera, or a video camera for planetary work, your diagrams will look quite different.

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