Quote:
Originally Posted by DavidTrap
Looks like Chris has got you on the right path. I'm assuming his direct motor connection is to the 10:1 reduction shaft of that focuser.
The documentation is fantastic for an open source project!
DT
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No it couples to the main focuser. 16 microsteps within 200 steps per revolution gives plenty of microsteps in the critical focus zone on my scopes. The documentation with myFocuserPro has excellent detail and explanations of it all.
Also I used a TMC2130 stepper driver which is very smooth and quiet. Much better than drv8825s etc - but they all work. And as David mentioned the ascom driver let's you turn off power to the stepper so you can manually focus - not sure why you'd want to do that though as the controller loses its place.
Edit:
The calcs are as follows
CriticalFocusZone = 2.2 x FR^2. For my scope FR=5, so CFZ = 55um
If I direct drive the focuser (no gears) on my scope
- 1 turn of focuser moves it 15mm
With a 200 step/rev stepper using 16 microtstepping
- that gives 3200 microsteps per revolution which moves the focuser 15mm
- or 12 microstep within the CFZ of 55um. This is more than enough
So with your stepper with 27:1 gearing you don't even need to use microstepping. I prefer to use microstepping because then I don't get the backlash problems with the 27:1 gearbox.