I am running KStars/Ekos/Indi on my Raspberry Pi 4 4GB. On a reasonably clear, dark night tonight, I tried polar alignment for the first time. My telescope is an ED80 frac with 0.8x FR/FF and my image capture device is an unmodified Canon EOS 450D. Am I expecting too much from this combination in attempting to plate solve? I tried various exposure options and could see what seemed like a reasonable number of stars in each captured image. However the solver timed out at 180 secs each time it attempted to solve any of the images. I noted in passing that the solver process was occupying only one of the four cores of the RPi4, although that one was running at 100% occupancy.
I am referring this issue to the ‘general’ category since I recognise that there may be limitations in the capabilities of several parts of my equipment.

I’ve now had the chance to try online and offline solving of some of my images from last night. The offline solver suggested I needed more Index Files downloading so I am going ahead, but in any case it did the job that it didn’t do outdoor last night.
There seem to be discrepancies between the FOV results obtained from the onboard Astrometric Solutions (47’x37.6’) and the online Astronomy.net (2.61°x1.74° = 156.6’ x 104.4’). My own theoretical calculations with the assistance of Stellarium etc. suggested 2.38° x 1.46° or 143’ x 87.6’.
Is this because the CCD simulator is limited to 1280 x 1024 pixels?

Sorry - answered my own question! It is!

I wouldn't recommend a DSLR with the PPA tool. It will have very poor response when you get to the refresh stage. That being said it would be possible to.

I have performed PA many times with a DSLR and it works very well. Yes you need to be patient though...

More evidence gathered tonight. There is something wrong in the polar alignment automatic process (in my installation).
Evidence: With the mount parked and adjusted to put Polaris in the FOV and about where it would be if I used a polarscope, I started the automatic procedure. The solver gave up at 180 seconds. So I adjusted the default value to 300 seconds and tried again. Longer delay but same result. So I simply took a photo. I then asked the solver to ‘Load and Slew’ from this image and it was successful in 103 seconds. The same was true with arbitrary parts of the sky. I took several photos at random and each time the ‘Load and Slew’ command was successful. However at each slew location, an image was captured but never successfully solved.
Any thoughts?
I’m wondering if my installation of KStars/Ekos/Indi is corrupted or incomplete.........

I run a Celestorn C8-N (Newtonian) f/4.9 with a Canon T3i, which gives me a 1.28' x .85' FOV. I routinely use offline plate solving in Ekos with no issues whatsoever, as long as it knows what I'm trying to look at, i.e.in the neighborhood of. Sometimes it solves in only one iteration, other times if I'm further away from the target, six or eight iterations. Rarely does it give up and quit, but it has happened. Moreover, in my experience, I find plate solving in Ekos works just fine with my DSLR, but it does take several minutes - less so with my new RPi 4, 4GB.

Not sure, but I think load&slew does not restrict the FOV. If that solves properly, but not in capture mode then I'd suspect the FOV limits are wrong. They are computed from the setup info (detector size and focal length), and if they don't match it will never find a solution.

OT: I had similar problems when I tested my photo lens, a Canon FD 135. It would refuse to solve, even though I had inserted the proper numbers. Took me a while to realize that I had put the 20mm on, and the limit automatically computed for 135mm was just some 20' or so too high. Corrected that, and it solved in seconds....

Sorry - but I’m wondering what you mean by ‘as long as it knows what I’m trying to look at’?
When I’m attempting to polar align Ekos ‘knows’ that the scope is looking near Polaris. Equally, when plate solving at an arbitrary point, the mount ‘knows’ where it was slewed to....

What I have been trying, and it seems to work but I need to crosscheck it a few times more to assess consistency, is to align using the live view from the Canon and the alignment + polar alignment corrections from the mount control (in my case an AZ GTi from skywatcher with the smartphone app as remote control). Good news with this approach is that it is fast, you see the stars up to mag 3-4 pretty clearly even in the video stream (particularly if you use Magic Lantern and put a high LV gain) and you don't burn the shutter.

After two iterations the app was basically suggesting to move the mount so little that I decided to switch to EKOS to try exposing. My stars were not moving at all in like 2 minutes at 250mm. Maybe at longer exposures or longer FL it is not enough though.

Last night we had exactly this issue with a Canon EOS 77D. Only by putting the file format to JPG were we able to do a polar alignment. When set to RAW the resolver would time out. Very strange...

EDIT: For what it's worth, we are using Jasem's libgphoto2 repository.

Here are the align logs of last night. Unfortunately I didn't save the images used. I'll see if I can do that tonight.

$> grep align log_22-42-49.txt
[2019-08-27T22:43:11.738 CEST INFO ][ org.kde.kstars.ekos.align] - "Idle."
[2019-08-27T22:43:11.806 CEST DEBG ][ org.kde.kstars.ekos.align] - solve-field Revision "Revision 0.73, date Thu_Nov_16_08:30:44_2017_-0500.\n"
[2019-08-27T22:43:11.807 CEST INFO ][ org.kde.kstars.ekos.align] - "Detected Astrometry.net version 0.73"
[2019-08-27T22:43:12.692 CEST INFO ][ org.kde.kstars.ekos.align] - "World Coordinate System (WCS) is enabled. CCD rotation must be set either manually in the CCD driver or by solving an image before proceeding to capture any further images, otherwise the WCS information may be invalid."
[2019-08-27T22:43:57.739 CEST INFO ][ org.kde.kstars.ekos.align] - "Capturing image..."
[2019-08-27T22:44:07.991 CEST INFO ][ org.kde.kstars.ekos.align] - "Image received."
[2019-08-27T22:44:08.045 CEST INFO ][ org.kde.kstars.ekos.align] - "Starting solver..."
[2019-08-27T22:44:08.048 CEST INFO ][ org.kde.kstars.ekos.align] - "/usr/bin/solve-field -O --no-plots --no-verify --resort --downsample 10 -L 166.25 -H 275.1 -u aw -3 8.27358 -4 87.3053 -5 60 --config /home/wouter/.local/share/kstars/astrometry/astrometry.cfg -W /tmp/solution.wcs /tmp/fitsOL1720.fits"
[2019-08-27T22:44:08.088 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading input file 1 of 1: \"/tmp/fitsOL1720.fits\"..."
[2019-08-27T22:44:10.052 CEST INFO ][ org.kde.kstars.ekos.align] - "Extracting sources..."
[2019-08-27T22:44:10.453 CEST INFO ][ org.kde.kstars.ekos.align] - "Downsampling by 10..."
[2019-08-27T22:44:23.676 CEST INFO ][ org.kde.kstars.ekos.align] - "simplexy: found 170 sources."
[2019-08-27T22:44:26.203 CEST INFO ][ org.kde.kstars.ekos.align] - "/usr/lib/python2.7/dist-packages/astrometry/util/removelines.py:23: RuntimeWarning: divide by zero encountered in log\n logpoisson = k*np.log(mean) - mean - np.array([sum(np.arange(kk)) for kk in k])\n/usr/lib/python2.7/dist-packages/astrometry/util/removelines.py:23: RuntimeWarning: invalid value encountered in multiply\n logpoisson = k*np.log(mean) - mean - np.array([sum(np.arange(kk)) for kk in k])"
[2019-08-27T22:44:26.216 CEST INFO ][ org.kde.kstars.ekos.align] - "/usr/lib/python2.7/dist-packages/astrometry/util/removelines.py:24: RuntimeWarning: invalid value encountered in less\n badbins = occupied[logpoisson < logcut]"
[2019-08-27T22:44:26.428 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading sort column \"FLUX\"\nSorting sort column\nmmapping input file\nCopying table header.\nWriting row 0\nDone"
[2019-08-27T22:44:28.455 CEST INFO ][ org.kde.kstars.ekos.align] - "Solving..."
[2019-08-27T22:44:31.235 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading file \"/tmp/fitsOL1720.axy\"..."
[2019-08-27T22:44:31.241 CEST INFO ][ org.kde.kstars.ekos.align] - "Only searching for solutions within 60 degrees of RA,Dec (8.27358,87.3053)"
[2019-08-27T22:47:07.621 CEST INFO ][ org.kde.kstars.ekos.align] - "Solver timed out."
[2019-08-27T22:47:07.694 CEST INFO ][ org.kde.kstars.ekos.align] - "Capturing image..."
[2019-08-27T22:47:17.869 CEST INFO ][ org.kde.kstars.ekos.align] - "Image received."
[2019-08-27T22:47:17.884 CEST INFO ][ org.kde.kstars.ekos.align] - "Starting solver..."
[2019-08-27T22:47:17.888 CEST INFO ][ org.kde.kstars.ekos.align] - "/usr/bin/solve-field -O --no-plots --no-verify --resort --downsample 10 -L 166.25 -H 275.1 -u aw -3 9.06742 -4 87.3053 -5 60 --config /home/wouter/.local/share/kstars/astrometry/astrometry.cfg -W /tmp/solution.wcs /tmp/fitsGX1720.fits"
[2019-08-27T22:47:18.086 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading input file 1 of 1: \"/tmp/fitsGX1720.fits\"..."
[2019-08-27T22:47:19.792 CEST INFO ][ org.kde.kstars.ekos.align] - "Extracting sources..."
[2019-08-27T22:47:20.214 CEST INFO ][ org.kde.kstars.ekos.align] - "Downsampling by 10..."
[2019-08-27T22:47:33.780 CEST INFO ][ org.kde.kstars.ekos.align] - "simplexy: found 169 sources."
[2019-08-27T22:47:35.833 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading sort column \"FLUX\"\nSorting sort column\nmmapping input file\nCopying table header.\nWriting row 0\nDone"
[2019-08-27T22:47:37.880 CEST INFO ][ org.kde.kstars.ekos.align] - "Solving..."
[2019-08-27T22:47:38.980 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading file \"/tmp/fitsGX1720.axy\"..."
[2019-08-27T22:47:38.992 CEST INFO ][ org.kde.kstars.ekos.align] - "Only searching for solutions within 60 degrees of RA,Dec (9.06742,87.3053)"
[2019-08-27T22:48:01.991 CEST INFO ][ org.kde.kstars.ekos.align] - "Solver aborted after 44 seconds"
[2019-08-27T22:48:12.786 CEST INFO ][ org.kde.kstars.ekos.align] - "Capturing image..."
[2019-08-27T22:48:23.046 CEST INFO ][ org.kde.kstars.ekos.align] - "Image received."
[2019-08-27T22:48:23.062 CEST INFO ][ org.kde.kstars.ekos.align] - "Starting solver..."
[2019-08-27T22:48:23.066 CEST INFO ][ org.kde.kstars.ekos.align] - "/usr/bin/solve-field -O --no-plots --no-verify --resort --downsample 10 -L 166.25 -H 275.1 -u aw -3 9.339 -4 87.3053 -5 20 --config /home/wouter/.local/share/kstars/astrometry/astrometry.cfg -W /tmp/solution.wcs /tmp/fitszA1720.fits"
[2019-08-27T22:48:23.109 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading input file 1 of 1: \"/tmp/fitszA1720.fits\"..."
[2019-08-27T22:48:25.052 CEST INFO ][ org.kde.kstars.ekos.align] - "Extracting sources..."
[2019-08-27T22:48:25.474 CEST INFO ][ org.kde.kstars.ekos.align] - "Downsampling by 10..."
[2019-08-27T22:48:38.867 CEST INFO ][ org.kde.kstars.ekos.align] - "simplexy: found 160 sources."
[2019-08-27T22:48:40.916 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading sort column \"FLUX\"\nSorting sort column\nmmapping input file\nCopying table header.\nWriting row 0\nDone"
[2019-08-27T22:48:42.941 CEST INFO ][ org.kde.kstars.ekos.align] - "Solving..."
[2019-08-27T22:48:44.061 CEST INFO ][ org.kde.kstars.ekos.align] - "Reading file \"/tmp/fitszA1720.axy\"..."
[2019-08-27T22:48:44.071 CEST INFO ][ org.kde.kstars.ekos.align] - "Only searching for solutions within 20 degrees of RA,Dec (9.339,87.3053)"
[2019-08-27T22:49:05.146 CEST INFO ][ org.kde.kstars.ekos.align] - "Solver aborted after 42 seconds"