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ZWO ASI120MC for Planetary Imaging

Posted: Thu Jun 22, 2017 6:36 am
After about 4 months of waiting, the Sky God favored me for a while and I got a clear - very clear sky for about an hour or so. Taking the advantage of the clear sky, I put my new ZWO ASI120MC for the first time into my C9.25 SCT on the AVX mount to shoot both Jupiter and Saturn. Sadly enough, I was unable to see any images of my target objects through the camera despite these were distinctly visible through the eyepiece. Having failed in my first shooting attempt using ASI120MC and Sharpcap combination, I didn't waste my time as I saw some clouds started rolling in and I shot the Jupiter with my old EOS 60D and BackyardEOS combination.

Appreciate if somebody helps me as to how to use the ASI as I am a first time user of ZWO camera and Sharpcap.

Thanks in advance.

Digboi, Assam, India (Lat: 27 deg N, Long: 95 deg E)

Re: ZWO ASI120MC for Planetary Imaging

Posted: Thu Jun 22, 2017 2:03 pm
by turfpit

Here are the steps I used to capture this image of Jupiter
Jupiter.jpg (57.12 KiB) Viewed 1819 times
using a ZWO ASI120MC with Celestron C8 and 2x Barlow, settings file attached.

The alignment process:
  • Carefully align finder scope and telescope on a land based distant object.
  • Carry out a Solar System align using eyepiece.
  • Slew to planet, centre and focus.
  • Add Barlow (if used).
  • Centre and focus.
  • Replace eyepiece with camera.
  • In Sharpcap, set capture Area to 1280x960 (widest field of view = best chance of hitting the object).
  • Target will be out of focus, so is easier to find.
  • Centre and focus the target.
The capture process:
  • Set Gamma=50, ZWO recommended for planets.
  • Set Gain to 60% (70% if using a Barlow).
  • Turn on histogram and select Logarithmic checkbox.
  • Adjust Exposure until Right hand side of Histogram at 80%.
  • Run capture.
  • Reduce the Capture area to 640x480 and run a capture.
Histogram will look something like this:
ASI120-histogram.png (6.91 KiB) Viewed 1819 times
As I have become more confident with this, I add the camera instead of the eyepiece, turn on a reticule from the tool bar and Solar System align. The reticule helps with accuracy to centre the target.

Post processing steps were:
  • PIPP to crop and centre the target.
  • Autostakkert to stack the frames.
  • Registax for wavelets.
For Saturn I use a gain of 90% the rest of the process/settings are the same (see attached).


Re: ZWO ASI120MC for Planetary Imaging

Posted: Fri Jun 23, 2017 6:29 am
Dear turfpit,

I appreciate for the fantastic guide. I'll take a printout of your suggestion and apply it in the field as soon as I get clear sky. Actually I am used to using Canon DSLR with BackyardEOS for both planetary and DSO astrophotogrpahy (I'm a newbie). Having known that ZWO ASI cameras have high sensitivity and ASI120MC is one of the best cameras for planetary imaging, I purchased it only recently. Also I have not used Sharpcap before.

I thank you for your kind help which I acknowledge gratefully and will always remember your support.


Re: ZWO ASI120MC for Planetary Imaging

Posted: Fri Jun 23, 2017 7:41 am
by turfpit
Thanks Rajib.

Check out the SharpCap documentation at

The ASI120 comes with a 150 degree lens. This enables the camera to be used without a telescope, so it is possible to carry out some testing during the daytime from indoors. Just plug the camera into a PC, attach the lens and run SharpCap.


Re: ZWO ASI120MC for Planetary Imaging

Posted: Fri Jun 23, 2017 10:36 am
Dear Dave,

Thank you so much for your kind help and support. I'll surely do that and will come back to you to say you "Thank You" once I am able to successfully handle my new piece of equipment and also SharpCap. Learning through such help and support from person like you is really wonderful.

Thanks again and look forward to saying you my success story with your guidance.