ASI120MM (USB2.0) with Linux (guiding/planetary)

[freiform]

Hi,

is anyone using the ASI120MM (USB2.0, not 3.0, no -S) successfully  with Linux? I cannot get proper framerates at all (erratically jumping around <1 to 7fps). Guiding at longer exposure times might work, but lucky imaging seems not feasible. ZWO themselves are aware of problems and recommend other cameras for use with MAC/Linux. There are some reports of people making the switch to other cameras, some report it is working for them, but they never mention what they are actually using the camera for.

Before I start fiddling, replacing SDKs or recompiling kernels, does anyone have had success with planetary lucky imaging with this cam under Linux?

I am not really keen on selling an otherwise perfectly good camera. If I would go down that route, what would be a good (and not too pricey) alternative for guiding / planetary up to 1.5m (w/o Barlow) than works properly and without issues under Linux?

 

Thanks

Sven

[wimvb]

The camera has no stable linux driver and zwo don't support it. Those who have it working probably have slower frame rates, or found a sweet spot re framrate/gain/download time. You can experiment with powered usb hubs, etc, but it really is hit or miss. For stable operation under linux, you need to replace the camera with either the - S version or the mini version. 

[freiform]

It seems I can re-purpose the ASI120MM as an allsky-cam. Are there any alternatives to the -S or mini? Maybe an upgrade for planetary. Doesn't have to be ASI...

[JamesF]

I have had the 120MM working on Linux before now.  I've not played with it for a while though.  I think the main thing was to switch to the alternative firmware.  That does limit the frame rate a little, but it became more stable as a result.

James

[freiform]

Hi James,

the maximum I can get out of the 120MM is around 7 fps. But even that is not stable. It often dips below 1 fps. Not really ideal for planetary. It probably would work for guiding, though.

Yesterday I noticed something strange when setting up an allsky cam; when using the compatible firmware, I get fragmented images, indicating speed and/or transfer problems. After flashing the regular FW, the problem is gone and I can capture using my old RPi 1. But with the regular FW the camera won't run at all with FireCapture under Linux.

[JamesF]

It's possibly also worth fiddling around with the USB traffic control.  I've found it can make quite a difference to the stability of the camera when running oacapture.  I'll try to remember to dig mine out and try it a little later.

James

[freiform]

I set it to 40, which is the general recommendation for this device under Linux. That is actually the only way to get the 7 fps mentioned above at all. 

[JamesF]

Ok, I've just dug my 120MC out of the observatory and plugged it in to my Orico USB3 hub (because that's the only convenient way to get stuff on my desktop at the moment).

Using oacapture, I have USB Traffic set to "auto" and at 10ms exposure time I'm getting about 18fps for a full frame.

Edited August 27, 2019 by JamesF

[JamesF]

Oh, I'm not getting many dropped frames, either.

James

[freiform]

Ok, so it is working for at least one person. Strange. I tried different machines, Linux distributions, cables, hubs, and never came close to 17 frames per second.  You are using the old USB 2.0 only version of the 120mc? Which distro and kernel version are you running?

[JamesF]

Linux Mint 19, kernel is 4.15.0-58-generic (whatever is latest).  Definitely the USB2 model -- I don't have the USB3 version :)

James

[freiform]

I just tried the 120MM with FireCapture on Manjaro. With standard FW, Firecapture says 'Capture failed' and that's that. After flashing the compatible FW, disabling all auto-settings, setting exposure to 10 ms, I can get the camera to capture at nearly 18 frames/second for a couple of seconds. Then the rate drops below 1 fps, I get a 'stiched up' image. Sometimes it catches itself, sometimes not, it is just not reliable.

Doing the same with Windows works without issues.

Also, for using the ASI120MM for Thomas Jacquin's allsky cam [1], I have to use the standard firmware, the compatible variant introduces errors.

[1] https://github.com/thomasjacquin/allsky

Edited August 27, 2019 by freiform
link

[JamesF]

2 minutes ago, freiform said:

I just tried the 120MM with FireCapture on Manjaro. With standard FW, Firecapture says 'Capture failed' and that's that. After flashing the compatible FW, disabling all auto-settings, setting exposure to 10 ms, I can get the camera to capture at nearly 18 frames/second for a couple of seconds. Then the rate drops below 1 fps, I get a 'stiched up' image. Sometimes it catches itself, sometimes not, it is just not reliable.

Doing the same with Windows works without issues.

Also, for using the ASI120MM for Thomas Jacquin's allsky cam [1], I have to use the standard firmware, the compatible variant introduces errors.

[1] https://github.com/thomasjacquin/allsky

I have never used Manjaro, but if you want to try to build oacapture and try that, I'll try to help get you through the process.

Regarding the all sky camera, it says on that page:

"Note:* Owners of USB2.0 cameras such as ASI120MC and ASI120MM may need to do a firmware upgrade (This changes the camera to use 512 byte packets instead of 1024 which makes it more compatible with most hardware.)"

That firmware is the compatible version.  It makes the camera output consistent with the USB specification again (which it isn't, in its default state).

So why it should introduce errors, I can't understand.

James

[freiform]

The note on allsky's page is indeed strange. Or at least that here it has the opposite effect.

On the other hand, the manual for the ASI120 states that 

Quote

Our USB2.0 camera is not compatible very well with OSX & Linux.

So there are some problems and they are aware of it. If it could be resolved completely by using the compatible FW, then they would just point to that instead of spelling it out like that, wouldn't they?

Maybe I'll try building oacapture, should I run into problems I'd be glad to ask you for some hints, thank you!

Anyway, I just put the camera outside to do its thing with the allsky setup. I guess I just repurpose it for that and go for a new cam for guiding and planetary. Maybe even something that is capable of light EEA..  I am open for suggestions 😁

 

Edited August 27, 2019 by freiform
typo

[JamesF]

The problems with the USB2 cameras on Linux and MacOS stem from ZWO breaking the USB spec. in an attempt to raise frame rates.  Basically the firmware claims that certain USB data structures are larger than actually allowed (because it's faster to send a few large "lumps" of data than to send more smaller ones).  Windows appears to ignore this problem.  Linux and MacOS don't like it at all.  ZWO aren't the only ones to have done this.  QHY tried the same trick in the past, too.  The "compatible" firmware reduces the size of those data structures to be within spec., at the cost of slightly slower frame rates.

There may be other issues.  Perhaps the cameras don't share the USB bus bandwidth nicely when there are other devices on the same bus.  I don't know.

Why that should matter to the all sky application, I'm really not sure.  It will presumably just get a frame, or it won't.  If I get time I might have a look at it.

James