Yes you can save to the SD card. In EKOS set the Upload option to Local. Then set the Remote directory to /home/pi/whatever
If your userid is not pi then change the remote directory accordingly.

As kengs suggests, you can save images to the SD card, but it's not advisable as a long term strategy. SD cards are not really made for highly repetitive storage (as compared to an SSD). Expect the SD to wear out and fail at some point. I would tread lightly and ALWAYS have a backup SD burned and ready for when your SD fails....

FWIW, I've always run the entire process on the RPi--that is, only use the laptop as a display/keyboard.
That worked well, and I used an RPi3b for a year doing that (the year ending the day my RPi4 got delivered).
Time from end of capture to file on SDCard should be under 10s for that.

That said, today I would not use a 3b, but rather a 4Gb RPi4.
The cost is minimal compared to the rest of the equipment you have, and it's a significant upgrade.
Time to download from the camera to the RPi4 should be in the 2s range, though I haven't looked closely lately.

Wow! Thanks everyone for the quick replies:

dmsummers and hy and kengs - Great suggestion on the RPi4. I now have one on order and running the entire process on the Raspberry Pi makes a lot of sense. This will also give me the opportunity to move up to 5GHz Wifi (if I can manage the distance from the Pi to my access point). I considered connecting the Pi directly through Ethernet, but I don't want to snake a cable from outside to inside during those hot buggy summer nights or cold winter nights when I run everything from inside. When I take my laptop outside near the mount, then I'll give an Ethernet connection a try.

dmsummeers - I only use the SD card for capture on my camera and then move all the files to my NAS and process from there.

Actually, assuming you're powering your equipment outside with your house's A/C, you may not need to "snake a cable from outside".
I've been successfully using these: www.amazon.com/gp/product/B06WP2ZT5N/ref..._title?ie=UTF8&psc=1
powerline ethernet adapters and they work well, and are more reliable for me than the WiFi was.

Not sure how many frames you collect each night, but just keep in mind that the SD card will wear eventually. Still a good idea to have a backup. You'll be happy you have a Pi4, but remember that before you try to use the USB3 ports, you definitely need to switch to 5Ghz wireless (or run that Ethernet cable). 2.4Ghz won't work. The other thing to watch out for is power. Make sure your power supply is either the "official" one, or that you use a USB3 powered hub for your connections. It's tempting to use all those USB ports to power your goodies, but just don't! Use a powered hub and only have the data return from the hub back to the PI4. You'll be happier. Cheers, Doug

While waiting for my Raspberry Pi4, I followed the suggestion to capture the pix from my DSLR directly on the Raspberry Pi3. Wow, big speed improvement and I can quickly look at the captured image using VNC on my lap to connect to the Pi and display the Canon CR2 file.

Now I just need to figure out how to speed up using Ekos Align.

After polar aligning the mount, I go from the parked home position and slew to the first alignment star (typically Vega). It just seems to take a long time from capture picture to the solution. The longest time seems to be from capturing image to starting the solver. I have tried running both the remote solver (with astrometry on the Raspberry Pi) and the online solver. It takes 1:30m to capture and image receive. Solving iteration takes about 100 sec. So with about 8 iterations to get to a solution, it takes awhile for the first star alignment.

I have the Raspberry Pi connected directly to the EQ6-R mount and controlling it with EQMOD. I was going to try and use the hand controller to do the initial alignment, but I have problems if both the hand controller and Raspberry Pi are connected to the mount. There seems to be some sort of conflict.

I'm curious if any other EQ6-R users have suggestions on speeding up alignment.

Something wrong with your align setup. It takes 5 or 10 seconds plus the capture length for me (everything running on RPi4, ASI1600 camera, 600mm focal-length refractor).

Make sure you have setup an internal solver -- that is, don't have it go out to the astrometry.net website, do it all internally, and do it on your RPi. See the options for that at the bottom of the align page.
Probably the easiest setup and quickest solving is ASTAP, see www.hnsky.org/astap.htm to install on your RPi (you need to both install the program and either the G17 or V16 star database).
Then check ASTAP on the bottom of the align page. You can also install and use the internal astrometry.net with its star database.
I usually downsample the images by 3 or so with my ASI1600.
If this is not working quickly for you (e.g. < 15s iteration, perhaps less on a RPi4, I guess less than twice that on a RPi3) please post details on what you're doing -- e.g. image of your align page and what's running on what.

Hy

Hy:

Thanks so much for your detailed and quick reply! As I mentioned, I'm using a Raspberry Pi3B while I wait for my Pi4. I have installed Astrometry on the Raspberry Pi and have tried using it for alignment and it works (occasionally I get solver timed out message), but slowly. I'm going to give ASTAP a try. Thanks for the tip. Based on your experience, I now see what's possible.

I'll post back with my results. One other question, are there some setup parameters that I should change for the mount (EQ6-R Pro) to improve the solving process (i.e.. less iterations).

Regards,

Peter

Still something wrong, as, although astap is faster, you should still be ok with a local astrometry.net.
Can you verify that your "slow" system is using the internal solver (as opposed to sending requests out to the web)?
FWIW, here are some pictures of what my align setup looks like for a local astrometry.net solve
photos.app.goo.gl/p3ZeWiyfwjDwwyyw8
Make sure "offline" is checked for you.

Note, if you moved that to astap, all you'd do (after installing astap) is check the astap box at the bottom of the first image in the album.

Hy

Cloudy skies, so I haven't had a chance to try it again and post my setup.

Peter

hy:

It's been awhile, but I have been testing and experimenting with your suggestions.

So here's what I have seen using the Alignment module:

It takes 1 sometimes up to 2 1/2 minutes from "exposure done" to "image received" using the online solver. It typically takes from 90 to 160 sec for the solver to complete:

[2020-08-02T22:47:12.246 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Capturing image..."
[2020-08-02T22:47:12.271 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 77D : "[INFO] Starting 15 seconds exposure. "
[2020-08-02T22:47:34.074 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 77D : "[INFO] Exposure done, downloading image... "
[2020-08-02T22:48:57.199 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Image received."
[2020-08-02T22:48:58.024 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solver iteration #1"
[2020-08-02T22:48:58.575 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Uploading file..."
[2020-08-02T22:50:10.007 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Upload complete. Waiting for astrometry.net solver to complete..."
[2020-08-02T22:51:38.925 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solver completed in 161 seconds."
[2020-08-02T22:51:38.991 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "WCS information updated. Images captured from this point forward shall have valid WCS."
[2020-08-02T22:51:38.993 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solution coordinates: RA (21h 01m 52s) DEC ( 68° 14' 28\") Telescope Coordinates: RA (21h 01m 52s) DEC ( 68° 14' 55\")"
[2020-08-02T22:51:38.993 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Target is within 00° 00' 26\" degrees of solution coordinates."

If i use astrometry on the Pi3, takes from 40 sec to over a min from "capturing image" to "image received" and 1 1/2 min to 2 min to solve:

[2020-08-02T23:52:11.655 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Capturing image..."
[2020-08-02T23:52:11.765 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 77D : "[INFO] Upload settings set to client only. "
[2020-08-02T23:52:11.768 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 77D : "[INFO] Starting 15 seconds exposure. "
[2020-08-02T23:52:33.359 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 77D : "[INFO] Exposure done, downloading image... "
[2020-08-02T23:53:11.049 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Image received."
[2020-08-02T23:53:11.052 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solver iteration #1"
[2020-08-02T23:53:59.464 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Starting remote solver..."
[2020-08-02T23:53:59.641 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Astrometry : "[INFO] Astrometry solver is enabled. "
[2020-08-02T23:54:13.031 Eastern Daylight Time INFO ][ org.kde.kstars.indi] - Astrometry : "[INFO] Solving image... "
[2020-08-02T23:55:45.702 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solver completed in 93 seconds."
[2020-08-02T23:55:45.728 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Solution coordinates: RA (21h 37m 45s) DEC ( 57° 28' 48\") Telescope Coordinates: RA (21h 36m 37s) DEC ( 57° 29' 21\")"
[2020-08-02T23:55:45.728 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Target is within 00° 16' 53\" degrees of solution coordinates."
[2020-08-02T23:55:45.743 Eastern Daylight Time INFO ][ org.kde.kstars.ekos.align] - "Syncing to RA (21h 37m 45s) DEC ( 57° 28' 48\")"

What I find interesting is that when I am capturing images in the CCD module locally to the Pi3, it takes only about 10 sec from image captured until I can view them on Pi3.

I was thinking that the difference is that the alignment module is sending a copy to Ekos running on my laptop as well as capturing it on the Pi, thereby making the process much longer. If I'm using Astrometry for solving on the Pi, why would it send an image to EKOS on laptop?

Thanks for all your help

Peter