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Old 03-12-2019, 02:54 PM
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Swagman105 (Geoff)
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Critique requested

Been dabbling for a while but recently got my first images with a decently aligned set up (thanks to a polemaster) from my driveway in suburban Geelong.
I've posted three images Canopus, Orion nebula and a random faint starfield. They were taken using an old Vixen 80mm F9 (720mm) telescope I picked up cheaply from a garage sale because the Vixen Great Polaris (SD-1 controller) set up it was on didn't work and the scope had some fungus issue which I've since done my best to clean.
The images were taken with it now mounted on an Ioptron ZEQ 25 mount and a Canon M6 mirrorless with single exposures of approx. 60 seconds each at ISO 1600. There were clouds about and were caught slightly in the Orion image.
I noted the significant flaring around Canopus and some vignetting in the cloudier Orion image and wondered whether a better scope or technique could improve on these.
If there any other issues that readers might pick up in the images, comments that might help me in my future efforts would be respectfully appreciated.
Geoff
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Old 03-12-2019, 03:03 PM
Imme (Jon)
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F9 is a pretty slow scope and although 720mm probably isn't deemed a long focal length you probably are getting to a point where the quality of your tracking comes in to play.
Stacking - I'd definitely be looking at doing multiple images and stacking in something like DeepSkyStacker - you'll be amazed at the difference compared to a single image.


Oh....one last thing....dont image when it's cloudy! hahahahaha
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Old 03-12-2019, 03:17 PM
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multiweb (Marc)
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Nothing wrong with that scope. The field looks excellent and well corrected. There is almost nill chromatic aberration. You've got tight stars.

Canopus has flares. So what. That's a bright star. Nothing wrong with that. I think you're already getting very good results with what you have.

Flats will sort out vignetting.

Don't change anything you have and keep going.
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Old 03-12-2019, 03:43 PM
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Swagman105 (Geoff)
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Thanks Jon & Marc
These are the sort of things that I need to hear. Very encouraging re the scope and I think I will leave these decisions about my hardware aside for now and work with my existing scope and gear and try and get the best out of it before moving on.
I think stacking would probably be my next challenge and keen to see what difference it would make.
I have Registax 6.1 on my computer and wonder if this would be suitable for stacking subs from a DSLR or whether I would need to go to something like the Deepskystacker.
Also would appreciate any opinions as to whether there is an optimum number and duration of subs.
Geoff
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Old 03-12-2019, 03:46 PM
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multiweb (Marc)
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If you still want to spend some money get a second hand cooled CCD/CMOS OSC and get into longer exposures. Plenty to do before you get bored and move on.
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Old 03-12-2019, 03:50 PM
RyanJones
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Excellent efforts there Geoff.

If any critiquing id second what has already been said. Flats will help with the vignetting and there are one or two potential dust spots/marks that the flats will take care of also. As has also been said, take multiple exposures and stack them. I’d also suggest in that same breath to pull back slightly on the ISO to help with dynamic range. You don’t need to capture the entire image in one shot. Multiple images with flats and dark frames will give you a better end result.

I’m suprised at the lack of noise in these images. Are you shooting in RAW or JPEG and are you using any in camera noise reduction ?
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Old 03-12-2019, 04:13 PM
raymo
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Registax is for stacking and processing lunar and planetary images; you need Deepskystacker,
its a free download.
raymo
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Old 03-12-2019, 04:20 PM
Mickoid (Michael)
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That scope is a keeper Geoff. Looks like you've done a good job with the cleaning and because this scope is possibly an achromat, the smaller f number has controlled the CA very well. It won't be long before you'll be posting some very impressive images taken with your set up, once you learn to stack your images with calibration files. Well done!
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Old 03-12-2019, 04:25 PM
Xeteth (David)
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Hi Geoff, you've done a great job with some first images there - well done!

Entering into the world of astrophotography can be quite daunting, there is a lot to learn and often it can seem a bit overwhelming (it was for me at least). However, if there's anything I'll say is that there's an amazing online community with ample guides available and many people willing to help out. Keep chipping away at it and you'll find it incredibly rewarding with the progress you make.

As the others have suggested, flat frames with assist with removing vignetting from your images. I suggest having a good read about the different types of calibration frames that are often employed to improve images and reduce errors that are inherent in cameras etc. The common ones to read about are Flat frames, Dark frames and Bias frames - this page should give you an overview of what they are and what they do http://www.rawastrodata.com/pages/typesofimages.html

Stacking will certainly help, the idea being that we want to increase the signal-to-noise ratio (SNR) of our final image. The precious signal from that target we are shooting is essentially always there, whereas the noise from the camera is random, as such if we take lots of images and stack them the noise is averaged out.

That is a very basic overview and I suggest reading further into it - there's a ton of really great resources out there that will explain it better then I ever will. Overall though, great first effort - I'm sure you'll become addicted like many of us in no time!
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Old 03-12-2019, 07:23 PM
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Swagman105 (Geoff)
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After checking my camera settings, the images I took were indeed JPG with an intermediate noise reduction setting. I have now set it to take RAW images as well and downloaded an extension to view the raw images on my computer.
I've also downloaded deepsktracker, so now I await clear skies for another go maybe half dozen one minute images at a lower ISO say 800 and a few dark frames.
Thanks all and I will post results on this thread again but unfortunately not tomorrow by the look outside.
Geoff
PS Have included a picture of my set up. There is not much detail on the telescope as to its type or model number (a few other labels have faded and are unreadable) but given the results to date am happy to persevere to the point where any limitations become obvious and point to what I should be looking to overcome in an upgrade step.
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Old 03-12-2019, 07:24 PM
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Lovely setup and good job on the cleaning, from the quality of those samples I'd say that you got away with a steal.
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Old 03-12-2019, 07:36 PM
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Wussell (Russell)
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The ISO sweet spot for a canon is 800, give that a try, especially when you start to stack images
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Old 03-12-2019, 08:10 PM
raymo
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Different Canon models have different sweet spots, for example my 1100D was 1600, but my 600D is 800.
raymo
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