How can I set up a forced autofocus after the telescope slews to a new target, or more importantly, immediately after a meridian flip? I have a C11 Edge HD with 0.7 reducer and Foresight Innovations ONAG. When my slews are large, and especially in meridian flip the mirror shift causes the images to go out of focus. With the ONAG, the stars become extremely elongated when out of focus, so the PHD detects each individual star as two stars that are too close together to be used as a guide star. I need to be able to have an autofocus occur in a sequence before the PHD guiding resumes. It is not so critical for the auto centering because the primary image stays round even if becoming a little donut. But for the ONAG guiding image, PHD becomes completely hosed up when the focus is not close.
Sorry if this detail was not previously apparent. With the ONAG the focuser control for the main C11 mirror adjusts the focus for the primary image and the guide image simultaneously, as both images are generated from the main optical path of the C11 using a dichroic mirror.
There is an option under Focus Control /Settings: ‘AutoFocus after automatic centering action’. Does this perhaps achieve what you are wanting? PHD2 can be paused while the autocentering is in progress.
Hi Mike, Thanks for the suggestion; however, I had already previously found this switch and had it activated for the sequence I was running. So, this does not appear to be a solution for my case.
After reading how to report an issue, I guess I need to restart. Here are links to my sequence file, the log where the problem was identified, the PHD log file, and a set of guide images that failed to find a good guide star because of the extreme elongation of the star images through the ONAG when C11 was not in focus after the meridian flip.
As stated above, I did have the autofocus after auto center option active during the running of this sequence. However, it appears that at the end of the auto center operation just after the meridian flip that the sequence attempted to resume PHD guiding prior to an autofocus. Please see the log at 1:33:15.095 to 1:33:15.535 to see where auto center successfully ended and PHD guide resume started w/o a call to autofocus. The linked PHD images show the guide image upon several attempts to find a guide star that failed. I believe due to the image being out of focus. After the PHD resume call failed, the sequence went into recovery mode and continued to struggle. After about 20 minutes there was an autofocus call, which was primarily successful. This operation showed that the focus point had shifted from 28181 counts on my C11 focuser to 28159 due to the meridian flip.
I hope this is sufficient for Main Sequence team to help me with this issue I am having. If not, please let me know what else you need.
Just to let you know the links in the above post are not working.
I’m guessing here but in PHD2 on Advanced Settings / Camera, there are some parameters for adjusting the SNR level for what can qualify as a guide star. If I am correctly interpreting what you say above then maybe the SNR levels of your elongated, out-of-focus stars are failing to achieve the necessary qualifying level. Maybe there is an option to reduce the target SNR level somewhat so PHD2 gets a ‘fix’?
Beyond that idea it seems you need the devs to take a look.
Thanks for letting me know the link is bad. I will fix it post haste. As to PHD settings of SNR, I have played with that setting, but I don’t think that is going to be useful here. If I am reading the PHD log correctly, it rejects most of the stars because each one looks like two closely spaced stars, and states they are too close for use as guide star. The stars it is willing to select are ones with extremely low SNR (like 10 to 20), which I think actually means the elongated shape is becoming lost in the background. However, PHD does not seem to be able to keep lock on these very low SNR stars with the lower limit of 6 pixels I had placed on HFD.
I am fairly convinced that the only real solution to this is for SGP to allow an autofocus immediately after the meridian flip slew. It seems to be doing this for slewing to a new target, but not for the slew caused by the meridian flip command.
Sorry for the bad link to the files in DropBox. Here is a link that should take you to the folder in DropBox where all of the previously listed files and fit images are:
I have asked for the same facility David. I have a C14 Edge HD and the same issue applies. The other issue is that with a large slew is that you may be looking through more or less atmosphere. My experience with planetary, says that the focus generally needs to be tweaked when I go from say Saturn to Jupiter for example.
I have a conventional OAG. In my experience the focus is still perfect after a meridian flip, where, by definition, the OTA is pointing to the same area of the sky.
Niall