I think I understand your problem I personally dont own a Star adventurer but have friends who have used it and they say they can get around 30s exposures without star trailing.
I tend to capture 30s exposures too on my HEQ5 Pro and my camera generates 26Mb files and these take 30s + 0.25s to store on SD card. I run Kstars/Ekos + INDI on RPi 4b and VNC onto it to manage. Hope this helps.

My latest tests seem to show some improvement when using the Fast exposure option in Indi, which decreases the extra time from 3 to ca. 1.6 s.
Unfortunately, this causes the pi to slow down highly with numberous short takes (flats, for instance).
Examining the log, I could notice a few things :
1- ok, let's ignore the first two warnings, I am not using the scheduler.
2- line 104 reports an error about invalid aperture, which repeats further twice on lines 103 & 131 :3- it takes 1.7s before the image is reported as saved by indiand then by kstars capture moduleand finally is stated as aquired4- then, it takes ca. 1.5 s for each new image to be saved, and finally the total time for a 60s sequence is 1min 41s and 1/3 - almost 70% more than expected.
The more the takes, the bigger the differential.
Beside the use of a faulty mount, the need of reducing the exposure is the brightness of the object. I previously used a dSLR, and when I needed to capture bright objects I decreased the exposure rather than the sensitivity - which in most cases was the least.
Another reason is the flats, that must be taken with ETTR @1/3 ; with my lenses, it gives 0.75s @f/8 and 0.075s @f/2.8, and that leads to a total freeze of the system near the end with 63 flats.
According to what I read, there is no reason for such a differential : the used media are rated class 10, and the power source is capable of 5A.
Rgrds,
J.-L.

How strange...seems like the camera/Ekos is reporting an incorrect value to INDI??? Could you send screenshots of the Capture tab & the details in the Optical train please.
Could you also try taking longer exposures (say 20s) and see if the 1.6s changes?

Here you are.
I don't know what really happens, but it seems it does not behave the same from a launch to another.
This one, for instance, displays many warnings/errors. Much more than any other previous one.
Also, it sometimes complains about aperture not be set, or both focal and aperture, or setup not being found, or displays empty fields in indi where it should be data,.. etc.
If I can find some time, I will try to launch several sessions and keep trace of what I can notice. But it might take very long.
Just one more thing : I did have previously added my 2x TC in the Lenses tab, as a barlow.
When I opened the tab to take a screenshot and attach it here, the entry had vanished.
The only change inbetween was the update. But I would not have thought it could affect the database.
Rgrds,

Have you tried resetting all the parameters to default in INDI and setting them directly thro Ekos?
Also I tried adding a lens with a similar configuration as yours to my simulator and when I capture an image the FITS file reports a different focal length. Strange. Could you look at the FITS header on one of your captures and see what it shows? I used Siril for getting that info.

Hello,
New attempt with a 60 x 1s seq followed by a 60 x 20s one, debug on.
An update was awaiting, I did it, closed all and relaunched the debug.
First try : 20s seq took 10s< before it started, then it crashed after 4 shots.
The sw automatically relaunched after more than three minutes, but nothing happened for at least five more so I closed everything.
Unfortunately, there was no logs in either Indi or Kstars windows, so I closed the debug and restarted it a few minutes later.
Second try - much smoother than the first. Everything went fine, I could save the log.
Just one thing : I took two screenshots of indi Options tab before each try : 06-Indi03 before the first, and 02-Indi02 before the second.
I did rename them in the wrong order, and I used the 02-... for another thread, so don't pay attention to the outlined Enregistrer button.
The only relevant values are the Scope ones.
As you can see, they differ between the two screenshots. There was obviously something weird with the first launch, and that could explain the crash.
Finally, the log. If I did not make calculation errors, it seems the differential for 20s takes is only 6%, wereas it is 65% for 1s ones. Very strange.
As for the reported values of aperture, this is normal. One must type the real aperture (diameter & obtruction) instead of focal ratio in the telescope tab.
For instance, for my Nikkor AIS 500mm f/8, I had to type 62,5 (as shown in the indi options tab), which is the result of diameter (85mm in my case) minus obstruction diameter (22.5 here).
About the fits values : for TELESCOP, it says "Telescope simulator", "500" for FOCALLEN and "62.5" for APTDIA.
So, except for TELESCOP, (which I did already report), everything seems OK for me.
BTW : I could provide my sql data if you need.
Rgrds,

I am not technical enough to understand the logs or SQL data Perhaps others who are more techie can assist with that aspect.
Personally the lowest exposure I have attempted is 5s and had no delay issues. For planetary imaging I prefer using software like FireCapture and record as video to get the shortest exposures.

DUPLICATE
I am not technical enough to understand the logs or SQL data Perhaps others who are more techie can assist with that aspect.
Personally the lowest exposure I have attempted is 5s and had no delay issues. For planetary imaging I prefer using software like FireCapture and record as video to get the shortest exposures.

Jean-Luc,

A quick question regarding your lens settings. First, that's a very interesting lens with a likewise interesting history. I had not heard of it before. Anyway, I use a Celestron EdgeHD 11" which itself has a central obstruction but I never adjust the diameter/aperture for the central obstruction in any settings. I'm curious why you make that adjustment.

Because if I just set the diameter, it will result in erroneous aperture : 500/85=5.88, ~6, wereas this telephoto lens has an aperture of 8, so 500/8=62.5, which also is the result of 85 (diameter) - 22.5 (obstruction diameter).
Thus indi displays the right aperture.
BTW : I'd like the aperture be 6...
Now, I am hunting for a Nikkor AIS 1000, with f/D=11.