While waiting for astro darkness, playing with the ASI120 MM

[wimvb]

Still no proper astro darkness up here. Yesterday was a clear night, so I set up my scope and had a play with my guiding camera, an ASI120 MM (usb2 model)

I made some upgrades to my scope, which I wrote about in other sections (motor focuser, cooling fan, and squaring the focuser), so it was about time to test the rig before imaging season begins (a few weeks from now). I couldn't start alignment until 10 pm, when the first stars became visible.

Controlling my setup from a Raspberry Pi running INDI, with the windows version of Ekos/Kstars as client. I managed to fully automate my imaging, except for polar alignment, that is. The ASI120 will only cover 22 x 13 arcminutes of sky, and the polar alignment routine in Ekos needs at least 30.

Anyway, had a play with routines in Ekos, and camera settings, gain/offset, and came up with these stunning images. (not!) Note that all images are full size (chip diagonal = 6 mm only)

NGC6888 (Crescent) 50 x 10 second exposures, high gain

NGC 6946 25 x 60 second exposures, low gain

M57 43 x mixed 10 and 30 second exposures

Unfortunately, the camera refuses to work in 16 bit mode, so all subs are 8 bit. This is a know problem with these cameras. (The newer S model should work in 16 bit mode.)

Processing: stacking with Winsorized Sigma clipping in PixInsight, no calibration frames. Histogram transformation and curvestransformation.

At least I had fun playing again ...

[AKB]

Nice.  Have you ever thought of taking up EAA, rather than this long-exposure imaging lark that you seem to otherwise do?

 

[wimvb]

Not really considered it. I just ordered a mono cmos with lrgb filters, so I'll test that this season. The asi120 mm has a ridiculously small chip, and is only good for guiding, imo. Will see how its bigger cousin performs. But I'm sure I will try EAA at some point.

[Allinthehead]

Great to get out and have some fun while testing. I just got one of those 120 mm for guiding. Yet to test. Don't leave us hanging which cmos did you get?

[wimvb]

ASI174MM Cool with electronic filter wheel and lrgb filterset. The larger 1600 was over my budget. Besides, the 174 has pixels that are probably better suited to my setup/conditions, and is supposed to have higher full well. I first wanted to go for the qhy version with buffer and integrated dew heater. But I use INDI as my platform, and I'm not convinced that qhy cmos is compatible with this software. The camara should arrive before astro season takes off up here.

[Allinthehead]

Best of luck with it. Did you go for the asi filter wheel and filters too?

[wimvb]

Yes. Same brand, so should work together. But when I add Ha, I will probably go for Baader. I think that for rgb ZWO is ok, but for narrowband, Baader or Astrodon is most likely better. It's all part of a learning curve.

[Stub Mandrel]

The Pixel of my ASI120MC are 3.75um compared to 5.12 on my 450D. I think teh potential advantage is that it is much easier to use with a barlow. What fl scope are you using with it?

5 hours ago, wimvb said:

Unfortunately, the camera refuses to work in 16 bit mode, so all subs are 8 bit. This is a know problem with these cameras. (The newer S model should work in 16 bit mode.)

Is this just the MM mono ones? My laptop is not a particularly great one at all but:

 

[wimvb]

I use a SW 150PDS at 750 mm, which gives a pixel scale of 1"/pixel. The camera's refusal to deliver in 16 bit is supposedly due to poor design of the usb port/programming. ZWO fixed this in the newer model (asi 120S). This is from the ZWO website (my text formatting, same warning for both the mm and mc models)

Warning

• The lens can be screwed in too far, result in a scratch on the protect window! Please adjust it very slowly! Don’t turn it beyond the focus at infinity!
• Full resolution function of the ASI120 requires full 480mbs USB communication!
• Mac OSX may not compatible well. Neither Windows though virtual machine. Windows though Bootcamp is recommended. Or use our ASI120S USB3.0 Cameras which runs well under Mac OSX.

So it may very well be that with an older (slower?) USB the camera works better in 16 bit. As I replied earlier today in another thread: cherish that laptop. 

I've only used the camera in single shot mode which produces tiff files, not yet in streaming ser.

[Stub Mandrel]

I read that (and it isn't very well written) as meaning it runs fine under windows, but not OSX or Windows under most virtual machines.

[wimvb]

It's probably 'google translated' from chinese. If you also read forums (fora?) such as indilib, cloudynights, and even zwo user group, it becomes clear that it doesn't perform well on any platform. My, very wild, guess is that older computers have a slower usb port, and that that's the reason for it working on those machines.