Auto focus step calculation

I have used the exact formula you supplied many times for calculating the auto focus step size and just cannot seem to get the results you do.

Ive followed the instructions exactly as you have out lined them and received different numbers. The other night my step size, per the calculation was 150. That worked for a short time, then I was having issues. I redid the routine and came with 16, that was a disaster. So, for no logical reason, I simply set the step size at 75 and it worked before I hit the hay this morning. What is the trick here? In your instructions the example doesn’t provide a current in focus number, so its difficult to check even you math. Im no mathematician. SO what is a good round number to use? I have a Televue 127is, a feather touch Focus Boss stepper motor with about 19k steps per inch…thanks

You’ll need to find good focus first using a bhatinov mask or other methods. You can use the HFR readout in SGP and manually move the focuser until you get a min HFR. It doesn’t need to be perfect…but needs to be close.

Thank you,