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Guide Camera Choice: Help Needed (Not Another QHY VS ZWO Thread)

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#1 endlessky

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Posted 24 May 2020 - 09:04 AM

Hello,

 

I have been successfully using KStars/EKOS on a Raspberry Pi 4 - 4GB RAM to control my current equipment for quite some time.

I currently use Astroberry installed on a SD card and everything is connected to the Pi (I use a very old laptop running Lubuntu to remotely access the Pi with VNC Viewer, since the laptop itself is uncapable of running anything...).

 

Before jumping to Linux, I managed to make some astrophotography software work under Windows XP with the laptop, but I could never get it to control the camera. Rather than buying a whole new laptop, I decided to give the Rapsberry Pi a try and I have to say I am very satisfied with the performance. The only thing I miss is the fact that with EQMod under Windows I could use PEC, and KStars/EKOS only support it for Permanent PEC capable mounts...

 

Currently my setup is as follows:

 

Mount: Sky-Watcher NEQ6 Pro
Imaging camera: Nikon D5300 Astromodified
Joystick for fine tuning the framing
Astrometry for plate solving

 

So far I only used some Nikon lenses that I already owned from my every day photography (70-300mm, 50mm) for my astro-imaging, but I am in the process of acquiring some new gear:

 

Telescope: Tecnosky Triplet Apo SLD FPL-53 80mm f/6 V2 with 0.8x flattener/reducer

Guide scope: Tecnosky SharpGuide 60mm f/4

Guide camera: ?

 

I am pretty sure about the choices of telescope and guide scope (unless anyone has any advice to give on that same price range: the telescope plus reducer is under 1000 Euro, which seems to me as an awesome deal), but I would like some advice on the guide camera.

 

As I wrote on the title, the purpose of this thread is not deciding which camera is best between QHY and ZWO (as far as I understood, they are basically the same, if we consider the entry level guide cameras).

 

The purpose of this thread is deciding which one to buy with the following considerations in mind:

 

1) I would like for the camera to work with my current setup, under KStars/EKOS, with pulse-guiding (as far as I know it's better than ST4), connecting it to the Raspberry Pi 4 (if I need to purchase a powered USB Hub, it's ok - so far all the equipment that is attached to the Pi has its own power supply)

 

2) I would also like for the camera to work both with EKOS internal guiding and PHD2 as an external guider for EKOS, just to have the option of testing which method gives me the best results

 

3) It has to be relatively cheap

 

4) I would like for the camera to be "future proof": I also own a very old Celestron C8 (it's been with me since 1997), so once I manage to get the "easier" setup working (80mm imaging scope + 60mm guide scope), I would love if the camera could work also in an OAG setup with the C8 (so I would just need to buy an off-axis guider and possibly a reducer, instead of buying yet another guide camera)

 

5) Last, but not least, I would like if the camera could work also if one day I decided to upgrade from the DSLR to a dedicated astro-camera (I read on the INDI Forum of a lot of people having troubles running two same brands cameras at the same time, one for guiding and one for imaging)

 

So far my choices of guide cameras are:
-QHYCCD QHY5L-II-M
-ZWO ASI 120MM Mini (Mono)

 

Any other suggestions, in the same price range of the above mentioned, are welcome!

 

Also, for the refractor/guide scope setup I mentioned, would the color versions of those cameras be sufficient for guiding, so they could also serve as planetary imaging cameras? With an f/4 guide scope I shouldn't have any problem finding guide stars, correct? But probably they would not be good enough for the OAG and the C8...

 

I have read a lot of posts in this forum concerning the two cameras of choice and I have read of many people having troubles with both (expecially with drivers, even under Windows...).

I have also read of a lot of people having troubles with some versions of the 120MM (the Mini or the -S, I am not really sure) and Linux/Raspberry.

I don't know if the problems have since been solved, with the latest versions of KStars/EKOS, so any help is appreciated, expecially from people that have a working Raspberry setup with those cameras.

 

Since, as we all know, astrophotography is an expensive hobby/passion, I would like to make the right choice and be sure that the camera I will buy will be fully compatible with the hardware/software I am using.

 

I am sorry if these questions have been asked before, but as I said, I would like to buy something and not have any bad surprises along the way!

 

Thank you all for your help and clear skies!
Matteo



#2 Madratter

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Posted 24 May 2020 - 09:13 AM

I have a QHY5LII-m. It was incompatible with the USB on my one computer. It would work for a while and then time-out. I think the problem was the USB chipset on that computer. When I switched to another computer it is far more reliable and goes the night far more often than not.

 

The ZWO cameras I have no experience. They could be better or worse.



#3 rgsalinger

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Posted 24 May 2020 - 09:46 AM

If you want future proof get an off axis guider.  Guiding any long focal length telescope with a guide scope is a risky proposition. The last person who told me that they were successful showed me what they considered success. It didn't look successful to me. So, if you ever want to use that C8, put up with a bit of fiddling and get an OAG.

 

Either camera will work just fine. If you can't get two of the same brand to work on Indi, that's another matter but I do this routinely on Windows with ZWO and QHY. Each camera's ASCOM driver allows you to choose one of the cameras for your main camera and one for the guide camera. 

 

If you decide to keep going with this hobby, you really don't want all those USB cables,  a proper 12v powered industrial quality hub will save you from the USB blues that so many experience. It can be placed atop the OTA which means just one USB cable going to the computer. Much easier setup, less worried about the meridian flip, etc. 

 

Rgrds-Ross


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#4 Stelios

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Posted 24 May 2020 - 02:02 PM

I can't answer about Indi compatibility (I'm sure they would have a listing of compatible cameras and drivers), but as far as a guide camera, you would not be able to perceive any difference in guiding. And both are very adequate for use with a guidescope. For an OAG you would want at least the ASI290MM-mini. 

 

A color camera is far less sensitive, and in some situations under light-polluted skies you might have a problem with guide stars. That said, in practice a lot of people guide with cameras such as the ASI224MC without problems.



#5 TelescopeGreg

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Posted 24 May 2020 - 04:34 PM

I'm also using Astroberry on a P4.  Works great!  VNC into it from either a laptop or tablet.

 

My guide camera is an ASI174, and I use INDI to talk to it with PHD2 (all running locally on the Pi).  Instead of Kstars / Ekos, I'm using CCDciel, but I expect Ekos would work just the same. 

 

My imaging camera is a Nikon D3200, which doesn't have good support for remote USB control.  It used to work (as long as I didn't go past 30 seconds exposure) on an earlier version of INDI.  I had all this running on a Pi3 under Raspbian Stretch, but something changed with the newer release, and I haven't been able to track it down.  Indi sees the camera, but fails to fully communicate with it.  I presume your D5300 will be fine, since it's supported. 

 

Because the D3200 isn't working under software control, I'm also using the guide camera for plate solving.  I aligned it to the main scope, and that's easily close enough to get the imaging camera on target.

 

To connect to the mount for pulse guiding, I believe you will need to get a USB to serial cable, and the special (Shoestring?) serial cable to connect to the hand controller.  There's an EQMod driver for Indi (indi_eqmod_telescope) preloaded on Astroberry, so you should be all set.  (I have an AVX mount, and connect the Pi directly to the hand controller with a USB cable.)


Edited by TelescopeGreg, 24 May 2020 - 04:36 PM.


#6 endlessky

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Posted 25 May 2020 - 12:57 AM

Thank you all guys for your help!

 

@ Madratter: I am sorry to hear about your QHY5L-II-M. Yet another proof of the connectivity issues of this camera. Unfortunately I read from some people that it works great and from others that they can't just make it work. So it's hard to find a definitive answer on this matter...

 

@ Ross: thank you for your suggestions. I am aware that with the C8 the only possible solution will be using an OAG, also to counteract mirror shift (my mirror is not locked, I still have the default focuser that the scope came with, that moves the whole mirror). On the other hand, the salesperson I spoke with about the refractor I would like to purchase adviced me to keep it simple for the refractor guiding setup and go with a guide scope... Also, the guide camera for an OAG would have to be a higher end model, making the guiding setup almost twice more expensive. Right now I am at the beginning of the learning curve, so I think I won't be using the C8 anytime soon. So I'll just probably stick with the cheaper combo of guide scope plus guide camera. The APO is already taking a big hit to my economical resources... bawling.gif lol.gif

As far as cable management goes, you are absolutely right. I will have to clean my setup. Right now I am doing "attended" astrophotography, so I am by the telescope for the whole acquisition session. The setup is already quite clean, cablewise. Everything is connected to the Raspberry Pi, which sits next to the camera, on the dovetail. From the Raspberry I have 3 USB cables: one going to the camera, one going to the mount, and another one going to the joystick. The only three cables going from the ground to the equipment are: 12V/2A power to the mount, 5V/3A power to the Raspberry Pi and the power for the dummy battery of the D5300. For these I would have to find a power-box type of solution, with controllable output switch and powered only with one cord to the ground power. The laptop is used only to control wirelessly the Raspberry Pi, via hotspot of the latter, and VNC desktop sharing to see on the laptop screen all the applications for astro on the Pi. So no cables going from the laptop to the setup.

 

@ Stelios: thank you for the tips! You confirmed what I was almost already sure about: for an OAG setup I need a higher end camera, which unfortunately costs twice as much... I guess for now the C8 will have to be used only for visual / planetary imaging... The ASI 224MC does not cost much more than the 120MM Mini or the QHY5L-II-M, so that could be a nice option, if it can provide guide stars on the guide scope and also serve as a color planetary/moon camera. I'll research more about it, thanks!

 

@ TelescopeGreg: thank you for your insights about the Raspberry. Except for the camera, your setup sounds exactly as what I am doing with mine. Everything is running locally on the Pi, I already have the USB to mount cable and I am able to control the mount perfectly from KStars, giving all the inputs for slewing and plate solving. So I am hoping I can feed the guiding pulses through that cable as well. I don't use the Synscan controller in this setup. Sounds like the problem you are having with the D3200 is the same one I used to have with my older D90. The D90 doesn't support Bulb mode through PC, so I was limited to 30 second exposures as well (I had to use an intervalometer in order to go over the 30 second limit). I bought a used D5300 to solve this problem and also to modify it for astrophotography (was tired of doing hours of exposures with the D90 only to not see barely anything from all the nice H-alpha regions of the beautiful nebulas I was trying to shoot...). The D5300 works perfectly under EKOS and I can push the exposure times as high as the situation demands, so I am very happy with it!

 

Thanks again everyone!

 

Clear skies,

Matteo




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