Hey Folks,

I've been testing again for a few days now and would like to mark this topic as [solved/workaround]. I changed the title and I added a reference to the end of the thread in the opening post.

Thanks for all the help and input over the last month and thanks especially to michael and jasem.

Here is a short summary of what ended up being the best approach for me:

AZ-GTI altazimuth mode (in my case the x-version)
Motor firmware 3.40
Kstars 3.6.0/ INDI from github
Cam for platesolving: ASI 120MM Mini (on 120/3 Scope)
Imaging: Raspberry Pi HQ Cam (on 418/76)

1. Pointing scope (0-Level) roughly in direction of the target
2. Boot pi
3. Connect to mount
4. Change mount-settings to:

- Options-tab: 100ms
- (Options-tab: disable Logging )
- Alignment-tab: Change to inbuilt Math / Press Reload OK
- Sitemanagement-tab: check time
- Tracking-tab: All standard (but Deadzone = 4 and Offsets all 0)

KSTARS solver setting "use scale"

5. Slew upwards a bit with "mount control"
6. Solve with option (sync) and slew with goto near the target (may take a few steps)
7. On or near the target: in ekos mount tab "tracking off" - and "clear model"

6. Solve first time with option (sync) - goto target and solve again
7. Check drift. if its there - start procedure:

- slew with goto to a random point near the target and solve with option sync
- slew with goto back to the target and check drift
- repeat in a kind of a circle around the target

The drift will disappear, but sometimes it only needs 3 sync-points and sometimes (much) more. I also set a sync point every now and then or clear the model after an hour or two.

It should be noted that the drift of course never disappears completely, but in my opinion it can be reduced to the level of the original synscan app. But the extreme drift in which the target leaves the FOV in a minute can definitely be slowed down to make images with an exposure of 12 seconds or longer possible. The rest is probably hardware, field rotation, loading, leveling and all the other tweaks that are recommended in the many threads about the az-gti.

Attached here is a picture from my bright city balcony from the last three days. It really only takes 5 minutes from switching it on to getting started, which is just a lot of fun for me... next stop - darker place and clear sky!

M51 - 840 frames with 11 sec (2h 30 min in total)