AutoFocus process failed by detecting star on CCD dead columns


#1

Hi !

I use a home made focuser and it works perfect with SGP (at least controls are perfect).
I can’t use the autofocus feature because SGP still consider wrong stars. I can’t achieve to make it detects correct stars. It still consider some dead column I have on my camera and It tries to calculate HFR on this bad columns.

So after the autofocus process SGP move the focuser to a bad position.

Here is a shot of what happen during the autofocus process.

I try to change some parameters with no success.

Thank you for your advice.


#2

You have no valid data in your image so SGPro grabs what it can find. Settings will do nothing here unless you can limit your range to eliminate “donut” stars. You will also probably want longer exposure time.


#3

Thank you for your answer.

I know ! The screen capture was just to show the problem.
When I start the autofocus process, my setup was focused (previously made with the bathinov mask).
When the autofocus starts SGP move slightly the focuser and the HFR calculation is done on dead column.
At the end of focus processSGP move the focuser at an invalid range and I have donuts everywhere :frowning:

I’ll try (as soon as clouds disaperead) to detail the complete process (with a longer exposure).

Thank you.


#4

Hi !
I finally found a hole in the clouds to make my tests !
All is ok now !
Because the ugly dead columns of my CCD, I need to use dark frames.

Since I use them(only 3 darks) it’s just wonderful ! Autofocus is working nice !

Thank you.

Gilles


www.mainsequencesoftware.com