My ZWO Camera recommendations with Prism

Hi All,

I’m finally back to doing some imaging after a very long hiatus. Finally got set up in the backyard for new moon last night. I made some changes/updates with my setup and I wanted to relay my results to the “hive mind” so that maybe some of you all will benefit as well.

My hardware: Orion Atlas EQ-G, Explorer Scientific ED127 (triplet), moonlight focuser, ZWO OAG with ZWO 290 mono mini, ZWO 1600mm-cool (Gen 2). Up till last night I was using a Hotec Field Flattener, and I changed back over to my Explorer Scientific Reducer/Flattener giving me a Focal Length drop from 952 to 665 mm (I used to use this reducer a couple of years ago but between I had been trying to get longer focal shots for some objects).

I have struggled with getting good guiding from my mount for years, even after having it “hypertuned” etc, and I found that the shorter focal length allows me more “wiggle room”, so I’ve resigned myself to shooting nebulae until I can afford a new mount.

For a while now I think most folks have been aware that ZWO has some issues with their driver. These issues manifest themselves usually if you have more than one ZWO camera hooked up at the same time, or if you take many exposures with a ZWO camera. The work around is to use the ASCOM driver through Prism setup in order to bypass the ZWO native driver. For a while now I was using a setup of having the 290 guide camera using the ASCOM driver, and the 1600 main using the ZWO driver. This was fine when I was trying to do longer exposures (less of them), but last night I decided to heed the exposure tables and try doing 30 sec subs on the Helix Nebula. I managed to get 111 30 second Lum subs from Auto Observation until it finally ended with the error of unable to obtain image from camera (this is the ZWO driver bug, I personally believe it’s some kind of memory leak because it seems to come up after MANY subs)…

So I’m going to use the ASCOM drivers with both camera’s tonight. I have done this in the past and did not get any issues.

So for those like me using dual ZWO camera setups, I would like to hear about your experiences. If I get several folks to post notes I’d like to share these stories with the folks over at ZWO to see if they would look into correcting the problems with the driver.

EDIT/UPDATE - I wrote this post before finding out that ZWO released a new driver in May 2020. I upgraded the ZWO driver and I’m currently trying an Auto-Obs night running with this driver and a LOT of 60 sec subs. So far so good and hope I did not just curse myself…

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Just for giggles here is the stack of the 107 good subs I took last night.

aaannnndd for even more fun, I ran outside and stuck a bunch of T-Shirts over the scope, shot some flats using Prism’s "Capture Calibration Frames’ function, processed them and cleaned up the above image a little bit. This one is just flat corrected and I did a little Deconvolution, and a little light noise reduction in PixInsight.

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Yes, I agree there is something weird with Zwo camera when more than one is used.
I have contacted ZWO people many times on this issues and support is what it is…
There is a new version of the driver (June) where things seem to have improved.
As Prism developer I’ve set a test machine where I’m running 2 camera 24h a day and see how it behaves. I did some changes inside Prism, where I avoid calling same function many times if nothing has changed (v 10.4.6). I’m doing tests and see how it goes.

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Thank you for all that you do! Yes I was hoping that ZWO would fix this without having to have you make changes to prism. I will check for a newer version of the drivers again and update.

We have several folks in the group who run multiple ZWO camera’s so I thought if enough of us contacted ZWO it might help. Sounds like you have already contacted them for us!!

Best Regards!!!

You could contact them and push as a user to have them to investigate.

Yes sir, I’ve tried that, I was hoping to recruit a few more folks here to also contact them hoping that if they get more reports they might investigate on their end. Meanwhile if I come across any tricks or workarounds I will post back to let the community know.