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Old 22-02-2021, 09:44 PM
rocco57au (Rocky)
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ASI 071MC Pro first light

Inspired by Martin's posts I decided to give OSC a go believing it would be far easier (for me) than mono imaging only to find that I would basically need to learn everything again from scratch .
After almost giving up hope of ever succeeding, I've managed my first decent image using my ZWO ASI071MC Pro. Coming from a mono system to OSC has been a bit of a challenge working out new techniques, gains and exposure length settings using a CMOS camera. Anyway, after many nights and countless hours this is the result.

Set-up:
ZWOASI071MC Pro: Gain 200: Cooled -10C
ZWO 2" Duoband filter
5 x 4 minute subs
PHD2 guiding (RA 0.18 DEC 0.06 Total RMS 0.19)
No darks
No flats
Sharpcap for Polar Align and capture.
Maxim DL 5 for stacking and stretching.
Photoshop for final processing.

I have many more subs to add but Maxim was crashing for some reason so I stopped at 5 subs.
Close examination shows weirdly shaped stars at the four corners of the image. I have no idea what could be causing this so some guidance would be much appreciated. My processing skills are basically "trial and error" and as much as possible I am always here looking for guidance as to what others are doing.

Comments are very welcome, positive or negative, as this is the only way I can improve, maybe
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Last edited by rocco57au; 23-02-2021 at 08:49 AM.
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  #2  
Old 23-02-2021, 12:44 PM
RyanJones
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Nice work Rocky,

I have the same camera and even though I had already been shooting dual band with a DSLR Iíve found using this camera very different too.

With the star shapes, did you use a minimum filter in your processing ? Thereís a box that says preserve squareness or roundness. I think Iíve come across this before when it was set on square. If itís on roundness you can lower the pixel level to sub pixel. I usually use about 0.5-0.6. Just a thought ?

Cheers

Ryan
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  #3  
Old 23-02-2021, 08:22 PM
rocco57au (Rocky)
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Quote:
Originally Posted by RyanJones View Post
With the star shapes, did you use a minimum filter in your processing ?
Thanks Ryan, I'll look into it, however the irregular star shapes were visible straight off the bat before processing... back to the drawing board
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Old 23-02-2021, 08:41 PM
Startrek (Martin)
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Hi Rocky,
Thanks for your kind comment , appreciate it. I still call myself a beginner after 3 years or so as Iím still learning this amazing hobby and only jumped across to cooled OSC August / September last year.
Your images are fine for your first attempt , you just need more data next time
Canít help you with your wonky stars as I use Startools in processing
As long as your subs are good ( nice round stars ) thatís the main hurdle

Any reason why your using Gain 200 on the 071MC ? If you look at the camera specs the full well is 48,600e at Gain 0 ( At Gain 200 your only reaching 5000e well depth which means your not pushing the camera anywhere near its max dynamic range which is 14 stops , your only reaching 11 stops ) At higher gains the camera does exhibit increased Read Noise but itís still quite low
In regard to camera cooling thereís not much more improvement in dark current from -5C to -15C , so your setting of -10C is fine
Maybe next time your out set your Gain to 90 ( unity ) or even Gain 50 to use more of the cameras dynamic range especially pushing 3 to 5 minute subs. Donít be reluctant to push full well at Gain 0 , the camera may surprise you
With the ZWO Duoband , like with all Narrowband filters the more data you capture the more benefit you get out of your filter
Try and dither all your subs and take darks which Iím sure your totally aware
As a rule of thumb I try and capture a minimum of 2 hours on an object with the filter
Well done !
Good luck the next time your out
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Old 24-02-2021, 11:19 AM
rocco57au (Rocky)
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Martin, your very welcome. Thank you for your long and detailed reply, information like this is priceless as I can find it very challenging to find and understand a lot of things on the internet due to my disabilities.

Any reason why your using Gain 200 on the 071MC ?

My histogram was pushed all the way to the left and my understanding was to have it back towards the center. So I played around for hours with different exposure lengths and gain settings until I came up with a combination that slightly resembled what I was trying to achieve. Not the ideal settings but I was able, for the first time, to accomplish something that was visually pleasant.

I now understand that there is a lot more for me to learn and I am considering various viable options for me to leave my gear outside without having to set up each night we get clear skies (provided my mind and body are up for it). This usually takes up a lot of time to set up and not to mention the amount of energy required which I seem to have very little of these days.

I'm looking forward to my next imaging session and will definitely put into action what you have given me here afterall, your techniques are producing results that belong in the more advanced section of this forum rather than the beginners.

As for wonky stars, I never had any issues with my Atik 314L. This is going to require some further investigation.

Thanks!
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  #6  
Old 24-02-2021, 12:41 PM
Startrek (Martin)
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Rocky,
Dont be caught up too much on the histogram, as long as your not clipping then use your eyes to see how much you can stretch the image without introducing to much noise or brightness
As far as setting up , in Sydney I leave my scope outside for weeks at a time ( mainly during the 2 weeks of the new moon. Iíve been doing this for years and just use an Orion scope cloak with a towel underneath to absorb any condensation moisture etc..
In summer , I usually find a little spider has weaved a web in my OTA ( newt ) , so I just use a thin duster to remove it. I also clean both mirrors at least once or twice a year due to dew , ash from home combustion fires in winter , moths etc....
It is getting harder and harder to set up and pull down as you get older , so leaving the rig outside for up to a month helps a lot
I just bring cameras and laptop inside after each session and make cable ends or connectors have tape over the ends to stop corrosion
My mount and OTA are still in good condition after nearly 4 years even being left outside in rain , hot sunny days etc....
You just have do regular checks on equipment and Collimation on the OTA etc..

Cheers
Martin
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Old 25-02-2021, 09:14 PM
rocco57au (Rocky)
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Thanks Martin, I think that I'm being too critical and as a result hindering myself from making any progress. I need to chill out a bit more as my 12yo says.

I managed a two hour session last night with new settings when I saw a break in the clouds and hope to process the data when I find the time. And.... I left the pier outside set up all leveled and polar aligned for the next session. I looked outside earlier and it looked like rain could be coming tonight so I packed the pier and brought it back inside again I'm a bit anal about keeping everything in pristine condition... this needs to change as I'm getting up in years and everything is getting too heavy to lug around.

My scope and camera gear can be easily removed from the mount for storage at the end of the night as it's all mounted on a dual saddle side-by-side system. All that requires connecting to set up are the cables to the mount, power and laptop.

Cheers
Rocky
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