RPi4 for lunar/planetary capture?

[daz]

Am thinking of building a Rpi unit for lunar/planetary capture - cheaper than a new laptop!!

Anyone done this?

Any pitfalls/watch outs?

Did you install an external drive (M2/SSD) as a boot drive??

 

The Argon ONE case looks very nice with support for both SSD and M2 drives!

Any thoughts welcomed!

 

[AstroKeith]

I use RPi4's for many applications. Mount side use for controlling the mount and camera is a classic.

I usually use the Astroberry suite, it is both free and very comprehensive for average users. VNC server is built in and I control everything remotely from a variety of viewers (Mac, Windoze and iOS)

You can choose to store files on the Sd card, USB stick or on the client computer. The RPi4 seems happy with almost any size SD card - but get a good brand, Sandisk or samsung.

The wifi on the RPi is pants, so I use a LAN cable. Otherwise add a wifi dongle to the Pi.

[AstroMuni]

Hi Daz,

I use the RPi for AP (mount control, cameras, guiding, image capture). As its a linux based OS, your choice of software is a bit limited (as compared to Windows). You can run software like Kstars/Ekos, CCD Ciel, OACapture or Firecapture.

I use a laptop on which I run Ekos and use INDI server on RPi, so the HDD is on the laptop. RPi has a 64Gb SD card.n

EDIT: I also use astroberry as it comes preloaded with all the astro software. And use an ethernet cable between laptop & rpi to avoid pitfalls of wifi drop outs.  But several folk run all software on rpi and remote into it via phone or tablet. You just need to get a larger capacity sd card.

Also Note that you cant use ASCOM drivers at the moment.

Edited December 1, 2021 by AstroMuni

[daz]

Thanks both

I have played with Astroberry in the past, so worth another look I think!

I'm aiming to have all capture done locally, rather than rely on wifi or tethered with a LAN cable, and just remote onto it for monitoring purposes. Once data capture is finished then I'll offload the files to the main PC for processing.

So, a 128GB SD card should suffice and not worry about an SSD/M2 drive then.

Cool!! List for Santa now in progress

 

 

[StevieDvd]

If you are going to transfer your images for processing then perhaps 2 x 64gb would better. It's a good idea to get used to having a spare setup sd-card in case an update comes along and causes an issue. The writing to/from sd-card of the OS image takes longer based on the card size (not the amount of data used) - writing your first image to the sd-card is the start but learning how to save a working setup and write that back to another sd-card is just as easy once you done it a couple of times.

Do you plan to remote control the setup?

As a starting point image capture and mount tracking (and Polar alignment) are easy enough to setup. Focusing remotely and later guiding for other than lunar/planetary gets a little trickier as it does on a PC setup.

If your PC/Laptop has no ability to read sd-card* you'll need a USB adapter too.

* sd-card referred to is actually a micro sd-card which tend to come with an sd-card converter.

[AstroKeith]

Along the lines that StevieDvd suggest, perhaps use a smaller SDcard for the OS and programmes, and an USB stick or 2nd Sd card in a USB holder as the data store.

Having a backup OS/programme SD card is very wise. Also use only the best SD cards.

[7170]

I do lucky imaging and the capture rate on a PI3 (with astroberry on it) using EKos would be lower than I would wish if I were doing planetary imaging again because it would not be a very small ROI.

You will want to do local saving. Turning off preview, using low resource mode, and ROI helps in EKos, but it is nothing like the speed that many planetary imagers would hope to get from modern high speed cameras and a laptop these days.

Using Firecapture on the PI is better though, but it struggles (UI becomes laggy/slow too) to to do full frame (1280x960) capture at speed. I just tried now and it chugged along at 0.7 FPS per second for full frame. 

Not sure how different a PI4 would be as I've not moved from the PI3 as everything is working at the moment, so others will have to chime in about what FPS rate they can get for what frame size/ROI size.

[AstroKeith]

9 minutes ago, 7170 said:

I do lucky imaging and the capture rate on a PI3 (with astroberry on it) using EKos would be lower than I would wish if I were doing planetary imaging again because it would not be a very small ROI.

You will want to do local saving. Turning off preview, using low resource mode, and ROI helps in EKos, but it is nothing like the speed that many planetary imagers would hope to get from modern high speed cameras and a laptop these days.

Using Firecapture on the PI is better though, but it struggles (UI becomes laggy/slow too) to to do full frame (1280x960) capture at speed. I just tried now and it chugged along at 0.7 FPS per second for full frame. 

Not sure how different a PI4 would be as I've not moved from the PI3 as everything is working at the moment, so others will have to chime in about what FPS rate they can get for what frame size/ROI size.

Hi,

The difference between a Pi4 and Pi3 is quite a lot (which model 3 do you have? 3,3B+,3A+). You should also make sure you have a 4GB model, so a Pi4B 4GB. 

Benchmark tests show the 4B to be up to three times faster than the best 3. Plus it has USB3 ports. 

[StevieDvd]

RPi4 8gb recommended for 3 reasons:

1. Will be better if a 64bit OS is used. A few Linux distros are 64bit, won;t be too long until others go 64bit.
2. Extra memory is used for speedier transfers of data (good for image capture) - based on tests done by Tom's Hardware 
3. You can't add memory later

 

[daz]

4 hours ago, StevieDvd said:

If you are going to transfer your images for processing then perhaps 2 x 64gb would better. It's a good idea to get used to having a spare setup sd-card in case an update comes along and causes an issue. The writing to/from sd-card of the OS image takes longer based on the card size (not the amount of data used) - writing your first image to the sd-card is the start but learning how to save a working setup and write that back to another sd-card is just as easy once you done it a couple of times.

OK - thanks for the tip!

4 hours ago, StevieDvd said:

Do you plan to remote control the setup?

Yes. Once set up and installed, the plan is to run it headless and just remote onto it

4 hours ago, StevieDvd said:

As a starting point image capture and mount tracking (and Polar alignment) are easy enough to setup. Focusing remotely and later guiding for other than lunar/planetary gets a little trickier as it does on a PC setup.

I've no plan to use it for deep sky - at the moment at least! Focusing is manual anyway on my Cassegrain...

4 hours ago, StevieDvd said:

your PC/Laptop has no ability to read sd-card* you'll need a USB adapter too.

* sd-card referred to is actually a micro sd-card which tend to come with an sd-card converter.

Yes, no issue here...

4 hours ago, AstroKeith said:

Along the lines that StevieDvd suggest, perhaps use a smaller SDcard for the OS and programmes, and an USB stick or 2nd Sd card in a USB holder as the data store.

Having a backup OS/programme SD card is very wise. Also use only the best SD cards.

The RPi4 has USB3, so i am assuming then, that would be fast enough for the high frame rate?

My initial thought was the larger SD card would be the fastest, but maybe not so..?

 

Thanks all

 

[daz]

5 minutes ago, StevieDvd said:

RPi4 8gb recommended for 3 reasons:

1. Will be better if a 64bit OS is used. A few Linux distros are 64bit, won;t be too long until others go 64bit.
2. Extra memory is used for speedier transfers of data (good for image capture) - based on tests done by Tom's Hardware 
3. You can't add memory later

 

Thanks - yes, had been reading up on the fact you can't upgrade the RAM! 8GB it is!

 

[AstroKeith]

6 minutes ago, daz said:

The RPi4 has USB3, so i am assuming then, that would be fast enough for the high frame rate?

My initial thought was the larger SD card would be the fastest, but maybe not so..?

 

Thanks all

 

The USB3 will help with frame rate, but there may still be a logjam in the processing. Depends on the software package being used too.

I dont believe there is any speed differences between card sizes. Cards are sold at various speed ratings, which have changed with the new UHS class. I buy Sandisk or Samsung class 10 A1, which I suspect are about as fast as the Pi internal bus can handle.

Most OS's handle disc transfers with some intelligence. The standard Raspian on which Astroberry is based seems very good at using RAM to help. 

[BCN_Sean]

I've not done planetary with my Pi, so only half a thing here.  With testing transfer rates to the machine (Pi4 8GB running Astroberry) as my imaging camera is gobbing out 70mb a time, even with a really quick SD card it's still orders slower than a USB3 flash drive, and then that's still orders slower than an SSD; so if you're lumping big data around or requiring a lot of sequential read/write, or caching then the latter is the better option not just as a data store.

Down sides to it, is that for it to work the drive may need to be connected to a powered hub as it may push over the peak on the internal USB hub; had that one one, not on another.  The other down side is that as of yet I've not found any imaging (as in disk) software that will treat the SSD the same as an SD or a flash drive (though this may be down to the controller in the drive holder) so each backup of the disk is the same size as the physical drive itself instead of being a compressed to used space only image.

[catburglar]

When considering storage performance for planetary imaging you may want to look at this: https://www.jeffgeerling.com/blog/2020/fastest-usb-storage-options-raspberry-pi

 

[7170]

6 hours ago, AstroKeith said:

Hi,

The difference between a Pi4 and Pi3 is quite a lot (which model 3 do you have? 3,3B+,3A+). You should also make sure you have a 4GB model, so a Pi4B 4GB. 

Benchmark tests show the 4B to be up to three times faster than the best 3. Plus it has USB3 ports. 

Currently I have astroberry running on a 3B+. It would be interesting to know what the speed difference between the 3B+ and 4B would to equate to in frame rate difference.