Final move for autofocus (V-Curve)


#1

I’ve been setting up the V-Curve training and had a question.

I want my final move of the focus action to be IN (towards smaller focuser position values).

If I use ‘IN’ as the V-curve direction and run the 1st light it will create a V-Curve moving from larger values toward smaller values. This is as expected.

Then if I run a autofocus action it will find the near HFD then move OUT (greater focus position) to the next position and then finally move OUT to the focus position.

If I do this experiment with the direction set to OUT and run the 1st light it will create a V-curve going OUT and also focus with a final move OUT.

It seems according to the docs if your choose a direction of IN the final move of a focus action would be IN. This is important for the final action to be against gravity for some OTAs, for example.

I can workaround by setting it to OUT - training the V-curve, then set it to IN and autofocus and I get the desired action. You just have to remember to set it back to OUT if you want to train any more V-curves!


#2

If i understand exactly …too check your question and all work fine switching “Focuser direction for Vcurve and Autofocus” flag from OUT to IN i need to go under sky. When i Can go i’ll test it if there’s a bug.

Anyway doing last move to achieve focus against gravity is not a good idea infact using IN is in red color to intend a choice can produce bad result. This is not related to OTA but to camera weight and focuser torque. This flag is usually reserved to OTA that have focus and camera on secondary mirror.

All the best
LO


#3

Thanks for the feedback - the scope is an SCT and the recommendation is to move the focuser knob CCW as the last move. With the stepper controller I built and the cable wiring it just happens the direction of ‘IN’ corresponds to turning the knob CCW.

I’m getting very nice V curves with the arrangement and focus is nice and quick.

Thanks!


#4

In this case, like i wrote in first message, i need to check on the sky. Only look at code is dangerous without test.


#5

Understood.

I might try a test using the ‘Reverse Focuser Direction’ option as that would seem to let me use ‘OUT’ as the direction and it would actually be moving the focus knob CCW like I want. Currently the knob moves CCW when the focuser moves ‘IN’.