Difficult weather conditions last night with passing thin cloud in patches. A good time to test.
I have problems with Linear 1 Pass focussing during an imaging run.
The above image shows a focus near the start during a period when seeing was a little better than other times. I know the focus position for all 3 filters is similar at step count 25,000 +/- 300.
Above shows an auto focus during poorer seeing conditions when the focus position was determined at 23,750 way outside the actual focus position. Inspection of the image taken immediately after the auto focus shows star images as small discs. I have a RC telescope. This happened about midway through the job but its game over now because the next auto focus starts from this erroneous position and this continues for all subsequent auto focussing with the focus position getting further off.
Would appreciate any help answering these questions:
1) How can I stop auto focussing having a successful result when clearly to the human eye they are not in focus? Is this a fault with the software or is there a better setting for star detection for a RC telescope.
2) The focussing mechanics has a max travel set of 2000 but focussing often exceeds this. In the example above the steps went from 23450 to 26550, a travel of 3,100?
3) As I know the optimum focus position +- a tolerance would it make sense to modify the interface to allow these values to be entered and if the focussing algorithm exceeds the range it defaults back to the known optimum position and tries again. Maybe after 3 attempts just reports a warning and carries on at the optimum position.
4) Warning in log: [2022-09-06T02:06:05.055 GMT Summer Time WARN ][ org.kde.kstars.ekos.focus] - Focus GSL error: invalid argument supplied by user. What did I do?
Out of focus image taken after poor focus.
Here are my focus settings:
Suspend guiding is selected but analyze bar chart shows this didn't happen? Trying to puzzle this out. Actually I don't know if its a good idea to suspend guiding whilst focussing. Mount is well aligned and no appreciable drift over the 3 second exposure.
I am also trying to understand what triggers the in-sequence auto focussing but will raise another Topic.