I've been stuck on this issue for a couple of weeks now. Just once I managed to get long exposures, but do not seem to reliably get it to work.
I have an RPi HQ camera on a RPi4 4GB, running astroberry 2.0.3. I did a fresh install a couple of days ago, to no avail.
Camera works OK with long exposures from the command line.
So far best way seems to be
Start up Kstars/Ekos & select profile
Set gain to anything other than the default '--" (dont seem to be able to change this default)
Try & do a long exposure - it will ignore the value and do a 1 second exposure first time
Thereafter it seems to respond to long exposure request
I'm hopeful for a solution, and in the meantime if I can help with any testing (I'm retired!) to try and pin down any issues I'd be more than happy.
I know about the problem and it is very annoying, sometimes I can get long exposures very reproducible. Probably we only need to figure out how to set the correct sensor-mode for the HiQ camera, but I have not found such documentation. Ive sent request to Sony about their sensor, but no reply. Berhaps I should ask Broadcom instead ..
I've found the following command line always works ok, first time, any time. Somethingabout First Mode seems rekey perhaps?
raspistill -t 1 -md 3 -bm -ex off -ag 1 --shutter 200000 -ISO 800 -st -o /home/astroberry/Desktop/long.jpg
Ok, done some testing today. Neither burst mode or hard setting a mode seems to help. Also I see that when I use raspistill to get a 5 s exposure it can take up to 45 seconds. That is really strange I think.
Yeah. That one had me stumped for a while. Seems that raspistill will go through several frames (around 7 of them) before it presents the final frame to the user. Each frame is the length of the exposure time that has been set. That is the very reason for implementing raspiraw in my driver after attempting to use raspistill.
For me, as written, the image is saved after about 1 second longer than the set exposure length. ie for a 5 second it takes 6.
If I remove the -bm, it gets a little longer.
if I remove -ex off, it does indeed get very much longer.
Just to make sure, when you say the image exposure does not change. You have turned of the stretch-button in the FITS-viewer then, otherwise the stretch function will normalize the exposure, with more or less noise as a side-effect.