Great V-curve, but out-of-focus image


#1

I get a great V-curve but my images are out-of-focus. When it finishes the V-curve the Focus Control window indicates the last point on the V-curve instead of the correct auto-focus point. What might be happening? Thanks, Rick


#2

Possible failure of focuser to return precisely to the the found focus position. Try using backlash compensation.


#3

Hi Ken, It works fine using Focus2 in Sky-X Pro. Focus is seems perfect most every time. I see the current position changing in the Focus Control window, but when it reaches the end of the V-Curve (8 points at 40 steps between points), it doesn’t go to the calculated point of focus. In fact, it doesn’t move at all. What should I try next? Thanks so much.
Rick


#4

I’m trying to understand what you are seeing. Unlike some other focus routines, SGP does not take a confirmatory image at the focus point. The one left on the screen will be for the last point on the left side of the V-curve. Is that what you are referring to?


#5

Yes, that’s right. So there is no way to know the position SGP has moved the focuser too after the autofocuser routine? Rick


#6

Yes there is - the focuser tab will show the new position for the focuser. To confirm, note the focus position before and after the AF routine.


#7

Or simply manually capture one more shot after AF run is complete to confirm that the capture is well focused.

Peter


#8

If the “focuser tab” is the “Focus Control” window, then it’s not moving after the last V-curve point. IOW, it doesn’t seem to move the focuser to its calculated autofocus point after the last V-curve point.


#9

If you saved the logs, you might want to upload the logs to a server and provide a link.

Peter


#10

Great! I searched the docs and found no reference to log files. What is the log file called and where does it reside? Many thanks. Rick


#11

All the infor you need on logs and other files is here:


#12

This seems to have been the problem. Thanks Ken.


#13

Are you referring to backlash in your focuser? Was backlash compensation disabled before?

Peter


#14

Yes, there was no backlash adjustment entered in SGP for my Microtouch Focuser. Now that I’ve entered “75” it seems to be working well. However the clouds moved in last night and I wasn’t able to test it extensively. Hopefully that solved the problem. Thanks! Rick


#15

That’s good to know. It’s okay to overshoot backlash compensation so if you are not sure that “75” is enough, increase some more.

Peter


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