Isn't the worm period of the AZ-EQ6 the same as the EQ6-R Pro, i.e. 478.69 seconds? Why are you trying to force it to 720 seconds?
Oh, one other thing, make sure the mode dial on the top of the camera is set to M, and not the green box mode or one of the scene modes.
I used a 400mm f/5.6 lens with my Canon DSLR once back in the day, and I didn't have the problem you're having. I let Ekos autofocus with the lens, and it worked. The camera did not try to autofocus before each shot.
The only thing I can think of, is my cameras are always setup with back button autofocus (the shutter button doesn't autofocus). On the 450D, change custom fn. 10 (shutter/AE lock button) to 1 (AE lock/AF). That will cause autofocus to be moved from the shutter button to the * (asterisk) button. Maybe that will help.
Since the cable and mount work fine on Windows, and you've tried older StellarMate images that used to work, and you've tried Astroberry, and none of them work on the Pi, I'm thinking the problem is the Pi (or its power supply).
Just curious, have you tried to verify that USB in general is working properly on the Pi? Try plugging in a USB flash drive, and copy files to/from the USB drive.
sudo apt install libindi-dev
Well, both SM devices can't have the same IP address. So you'd need to change one of them. Then in your Ekos profile, you'd change the host field to the new IP address.
On stock Raspbian, to change the IP address of the ethernet connection, you would right-click on the network icon at the top-right of the screen, and select "Wired and Wireless Network Settings", then it's easy to change the IP address of eth0.
On StellarMate, I think (but not sure) that they use a different network manager than Raspbian. I think StellarMate uses gnome network manager, so the button clicks/menu entries might be different, but the idea is the same.
On the EKOS align Tab there is no ASTAP option at the botton - only StellarSolver and Remote.
Yes, this is normal. As long as you have solving method set to "Local ASTAP" in the options, it will use ASTAP.
When I try to point the index files location to /opt/astap it will not load indexes and folder details say 'Dowloads disabled, directory permission issue.
Don't do this. That's only for astrometry.net, and internal solver. ASTAP has its own set of index files, which you must download and install from the same site you installed ASTAP. You will download and install a .deb file, and it will put the index files into the /opt/astap folder.
In fact, if you plan on only using ASTAP, you can delete any index files you see on the Indexes option tab in Ekos, as they aren't used by ASTAP.
Personally, I keep them installed, as I tend to go back and forth between ASTAP and local astrometry.net.
You've probably already tried this, but just in case you didn't (it wasn't mentioned in the OP), did you turn off the camera's auto power down feature?
Your proposal of a command line switch for kstars would be perfectly acceptable, if it can launch quickly (on my machine, kstars does not launch quickly), and if it's easy to associate .fits files with a program that needs a command line switch (without having to resort to a shell script). The second requirement can easily be satisfied by making a symlink (or hard link) of fitsviewer to the kstars executable, then when kstars starts up, it can check to see if it was launched as kstars, or as fitsviewer.
"But it shouldn't take 8 seconds to save the image to the SD card if you use Save Locally."
My Canon DSLRs download pretty quickly (a couple seconds at most). My friend that I mentioned earlier with the Nikon D5300, it takes nearly 10 seconds to download from his camera using StellarMate.
So maybe it's a Nikon thing?
Excellent, glad to hear it!
I like the idea of the internal solver, especially for other platforms (Windows and Mac) where it's a lot more difficult to install astrometry.net locally. I'm sure they'll get it worked out. But in the meantime, local astrometry.net works just fine, and is plenty fast (for me).
Unfortunately, the INDI Server for Windows has been abandoned by its author, and hasn't been updated in 2 years.
KStars/Ekos is meant to use INDI (or INDIGO) drivers, not ASCOM drivers. If you want to use KStars/Ekos on Windows, you have a couple options:
1. Install Ubuntu into a virtual machine in Windows, and add the KStars PPA, and install INDI and KStars. You would need to enable USB passthrough in the VM. People have had varying levels of success with this.
2. Get a Raspberry Pi (they are cheap), mount it on the scope, install just INDI on it. Then KStars/Ekos will run on your Windows machine, and connect over the network to the INDI drivers on the Raspberry Pi. Many people go this route, including myself.
I hope this helps.