Hi Adam,
Here is more to it. Today I have made the pulley I will use to connect the lens to the motor focuser. I chosen the same 180 teeth that I have made to the Canon 300 mm lens.
Here it is:
http://www.astrofriend.eu/3d-printin...m-bracket.html
Now it's complete and ready for some test photos, but first I shall test my Canon lens more. Take it out to some dark place relative my home in the city.
ps.
Your Canon 500 mm f/4 lens must be very exiting to use for astrophotography.
/Lars