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Old 23-01-2022, 05:26 PM
Stephane
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Skull & Crossbones

Hi all,

Another short integration image. At the moment, I'm enjoying just spending a few hours on images and moving on. I can always (and fully intend to) re-visit these targets in the future. They are not going anywhere! This image is clearly overstretched due to short integration time, and suffers from nasty moon gradients; but I am still pleased with the result.

Any tips for removing (or at least "taming" ) those nasty halos?? As always, please feel free to provide feedback re coma, collimation, focus, and other things.

Many thanks & clear skies,
Stéphane


Integration: 3h45’
Calibration: 50D, 30F, 50DF
Camera: ZWO ASI294mc
Filter: Optolong L-Extreme
Processed in Pixinsight, Gimp, Adobe Lightroom
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Click for full-size image (Chained Brooch.jpg)
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Old 23-01-2022, 07:52 PM
Mickoid (Michael)
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Boy Stephane, you're really pumping them out aren't you?
They just keep getting better too, won't be long before you'll be out of the beginner's section and posting your shots in Deep Space. Well done on advancing so quickly, you're obviously really enjoying yourself and taking in all the advice you've been given enthusiastically. Regarding the halos around the bright stars, not sure what causes that, I get them on my 8 inch Newt but not so much on my 6 inch Newt. Could be something to do with the type of mirror, collimation or just over exposure of the brightest stars. Hope someone else can offer an answer to that one for you.
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Old 23-01-2022, 08:14 PM
Startrek (Martin)
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Stephane,
Can you give me some your clear Sky time ? It’s been the longest drought of clear nights on the east coast in the past 4 years or so
Yes your certainly taking advantage of clear nights and imaging a variety of targets , well done again !!!
In regard to those halos around the larger stars , that’s perfectly normal for your 8” f5 newt , I have the same scope and don’t consider them to be an issue
You could apply a Star mask just on those few larger stars and use a star reduction algorithm ( Startools has the Shrink module which I use and has 2 features ( Dim and Shrink ) which will reduce that halo to taste )

Cheers
Martin
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Old 23-01-2022, 09:53 PM
Stephane
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Michael, I am really enjoying this hobby. Even setting up with attention to detail is great fun. Thank you for the kind words, still so much to learn though.

Martin, we’ve had a good run of three clear nights in the past four. But looks like last night’s session was the last for a while. Cloudy nights for the foreseeable future. Hopefully I don’t miss the new moon to image another galaxy! Thanks for all the tips.
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Old 24-01-2022, 07:10 AM
RyanJones
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Nice work Stephane. Your star field looks nicely corrected in this one. The halos are often cause by reflections in your imaging train. This can be the your filter or coma corrector or something like that. The light of the bright star bounces back and forth meaning the reflected light is out of focus when it reaches the sensor causing a halo around the star. They always become more pronounced when you are forced to stretch the image excessively. You can experiment by trying to move your filter either closer or further away from your sensor and see if that changes things or take some subs without your coma corrector of a bright star in the middle of you optical axis and see what changes that makes. Maybe try a few subs without the filter altogether and see if that eliminates it. Once you know what it is that’s causing it you can decide if you can or want to worry about it.

Cheers

Ryan
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Old 24-01-2022, 02:50 PM
Stephane
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Thanks Ryan, I will have to learn to live with them then. Although, they don't look too bad... I might consider spending a little longer on my future targets so as not to have to stretch so aggressively.

As for coma, I haven't changed anything to my setup, but used a more aggressive star size reduction which maybe killed off any coma. I might still need to tweak the setup a little by 1 or 2 mm!
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Old 28-01-2022, 04:13 PM
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Sunfish (Ray)
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Wel done Stephane. My favourite bunch of nebula. You have done a better job than I did in my first two attempts. A lot of great colour and detail with the different nebulae in that object.

I will have to take your lead a have another try with the Newt this time.
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Old 28-01-2022, 06:59 PM
raymo
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I wouldn't call 3hr45' short integration; it is equivalent to 15hrs with a
100mm scope, assuming that you were using your 8" scope.
raymo
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Old 31-01-2022, 09:54 AM
Stephane
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Thanks Ray, this was a fun nebula to process. Frustrating to capture though, as I had over 10 hours worth of images, but so many images went out of focus after the meridian flip. Now I refocus after meridian flips.

Raymo, I still find the top left part of the nebula in the image a little too faint for my liking. I hope to get more integration time one day and really draw out those faint areas if possible. It will be a good experiment. On a similar note, I posted here an image of Thor's helmet at about 4h integration. I would like to add 6 hours and compare the results. I'm looking forward to seeing what differences there will be (if any).
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