Nested "Stop at"

[yomamma]

I was doing something like this:

Stop at 2 degrees before meridian
Loop 20 times
Take a pic
End loop
Stop at 15 degrees before meridian
Autofocus routine
End Stop At
End Srop At

I tried this in an attempt to avoid hitting the 2 degree minimum while I was in the focus routine. When shooting high up overhead you go from 10 degrees before meridian to 2 degrees in about a minute or two, it is fast

If I am 3 degrees before meridian and enter my autofocus routine, the first thing it does is move out of focus by whatever amount I specify on the autofocus variables. If I hit 2 degrees at that point I am out of focus and I leave the autofocus routine. When I try to focus again I am too far off for autofocus to work.

When I hit 15 degrees it fell thru the 15 degree stop and then fell thru the outer 2 degree stop, even though we were still above 2 degrees.

Here is a copy of the log file zipped.

https://internetsearchtechnologies.com/ ... -10012.zip

15 degree fallthru starts at 23:34:14.

What is a good way to avoid this problem of losing the focus location in this manner as I was on the first focus step of 10 when it fell thru.

Thanks for your help.

Don

[admin]

Hi Don,

I'm going to have to have a good think about this situation (and test it). One odd thing strikes me immediately though... The progression of the movement towards the meridian is 4 minutes per degree regardless of where you are in the sky, so if you choose 2 degrees before then the remaining time to the meridian is always 8 minutes. This is because the 'degrees' value is measured in terms of the hour angle of the mount (measured in degrees rather than hours), not the azimuth (which would vary faster near the zenith).

cheers,

Robin

[yomamma]

Thanks Robin. I had forgotten about the degree computation.

[admin]

Hi,

I checked through the code on how this should work, and as far as I can see the nested 'stop at' should work pretty much as you would imagine - if the inner 'stop at' is hit then it will stop the steps inside it but that will not prematurely finish the outer 'stop at'. On the other hand, if the outer one fires first then it should come all the way out (even if it is running in the inner block). I wouldn't advise setting two nested ones with the same criteria, but you aren't doing that.

The only real thing I came across was that the autofocus step you are using doesn't return the focuser to the original position in the case of being stopped while in progress. The 'Refocus' step *does* return to the original position if it is stopped early or you cancel it. They were implemented at different times and I obviously took different decisions about what should happen in that eventuality. I am thinking about making the autofocus step have the 'return to start if cancelled' behaviour in future.

cheers,

Robin