Author Topic: [Theme] Night sky shots  (Read 79840 times)

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #360 on: October 21, 2024, 10:26:11 »
The latest image looks the most favorable to me.  It is slightly noisier, but the deep blue of the sky and the slightly clearer anti tail makes well up for the increased noise.  Again, thank you for sharing!

Thanks for the comment Akira. Yes I am also leaning towards the last version with blue background.
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Thomas Stellwag

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Re: [Theme] Night sky shots
« Reply #361 on: October 21, 2024, 14:12:19 »
one more vote for the last one
your work to obtain these images is fascinating
Thomas Stellwag

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #362 on: October 21, 2024, 19:18:20 »
Thanks Thomas.
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Brute

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Re: [Theme] Night sky shots
« Reply #363 on: October 23, 2024, 21:47:33 »
Great comet shots Oivind.
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Nasos Kosmas

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Re: [Theme] Night sky shots
« Reply #364 on: October 23, 2024, 23:14:38 »
Excellent shots Oivid once more :)

A couple of clean sky evenings  to shot the comet for me, so I garbed the opportunity :)
Unfortunately I didn't move  out of town as I would like to do, so town light pollution  was present
I used the 85mm 1.8 to locate the comet and then the old 80-200 Af D to make the shots at 200mm, then I added an 1.4 TC to 280mm f 4 ( I am no longer owner of the excellent 300 pf ...)
I used the Interval timer shooting of Z8 to grab 100 shots at about 1 sec f4 ISO 6400, then stacked on Sequator
 
The final result is not bad but because of light pollution the  camera was not able to record the comets big tail and the smaller stars around.

Second Image is from previous day with 200 mm f 2.8,  1.6 sec ISO 1000  because of the longer  time there is a trail on the stars but is overall richer

Thank you

Nasos Kosmas

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Re: [Theme] Night sky shots
« Reply #365 on: October 23, 2024, 23:52:22 »
Another stack with different settings on Sequator, enhanced details

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #366 on: October 24, 2024, 06:55:20 »
Thanks Brute and Nasos. Very nice captures Nasos, the core is so round and well defined in the last one! As time goes by now the appearance of the tail is fading as the distance to the the sun is getting longer.
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Nasos Kosmas

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Re: [Theme] Night sky shots
« Reply #367 on: October 28, 2024, 23:20:01 »
And finally I've got the opportunity  to capture the comet C/2023 A3A yesterday 27/10  in a less light pollution area :)
On the upper middle area of the frame you may see cluster IC 4665.
   
Nikon Z8 , 80-200 Af-D , 200mm f 3.2 , 1.6 sec  Iso 6400

50 Full Crop frames   Stacked  on Sequator.
Thank you :)

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #368 on: October 29, 2024, 08:37:31 »
Another nice comet capture, Nasos!

The winter storm blew out here (after causing everything to be encased in ice...), so I got an unexpected second opportunity on C/2023 A3 Tsuchinshan-Atlas Friday October 25. I did multiple sequences using Z8's 32 frame pixel shift mode to cause a minimal amount of dithering. For this first processing I used 20 frames over 10 min to minimize smearing of the core captured with the 300mm f/4 PF with f/4.5 front aperture, 30 sec ISO 500. The best view to SW was from my previous location on campus, unfortunately with lots of light pollution from street lights and the city, but at least no moonlight. The comet had faded considerably - I had to first home in using my 105mm lens before mounting the 300PF. For the first time I used Siril for the stacking and further processing, following a non-comet tutorial, with minimal adjustments in CNX2. The reverse tail is mostly gone (with some imagination there is an assymetric diffuse area in "front" of the core). The warm star Cebalrai is prominently catching the fading tail, with the cold Muliphen at the left edge.
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Akira

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Re: [Theme] Night sky shots
« Reply #369 on: October 30, 2024, 05:46:31 »
And finally I've got the opportunity  to capture the comet C/2023 A3A yesterday 27/10  in a less light pollution area :)
On the upper middle area of the frame you may see cluster IC 4665.
   
Nikon Z8 , 80-200 Af-D , 200mm f 3.2 , 1.6 sec  Iso 6400

50 Full Crop frames   Stacked  on Sequator.
Thank you :)

This is an amazing result for a set of "usual" camera rig.  It looks much crisper than the previous images.  Amazing!
"The eye is blind if the mind is absent." - Confucius

"Limitation is inspiration." - Akira

ColinM

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Re: [Theme] Night sky shots
« Reply #370 on: October 30, 2024, 09:40:04 »
Another beautiful capture Øivind

The warm star Cebalrai is prominently catching the fading tail,
with the cold Muliphen at the left edge.

There are 3 prominent stars in this image (the 3rd above and to the R of the comet body)
Each has clear black "bars" on either side.
Care to comnent on these?

Akira

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Re: [Theme] Night sky shots
« Reply #371 on: October 30, 2024, 10:35:03 »
Another beautiful capture Øivind

There are 3 prominent stars in this image (the 3rd above and to the R of the comet body)
Each has clear black "bars" on either side.
Care to comnent on these?

Colin, this African-talking-drum-like shape is not the shape of the star.  It is caused by the diffraction generated by the lens barrel.
"The eye is blind if the mind is absent." - Confucius

"Limitation is inspiration." - Akira

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #372 on: October 30, 2024, 11:12:17 »
Thanks, Colin. Yes Akira is correct, it is diffraction caused by smaller obstacles or shapes in the lens barrel. The front aperture (a 77-67mm step down ring) is intended to help prevent this and create a round aperture. However it seems to be harder to avoid when using a full frame sensor with bright stars closer to the edges. There is of course a tradeoff in terms of the light lost to the front aperture, so if it does not help much it is perhaps best to abandon it instead of using an even narrower front aperture. On the first comet captures I did not use it. (On captures with scopes that use a spider there are typically four very prominent diffraction spikes.)
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Nasos Kosmas

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Re: [Theme] Night sky shots
« Reply #373 on: October 30, 2024, 21:12:14 »
Thank you Oivid and Akira for your kind words  :)
 It was windy and some of the 50 captures was not in focus 100% so the stars became unnaturally bigger
The head of the comet also became  light full and not so smooth like Oivids  capture
Oivid did you found Siril more capable than Sequator?

Øivind Tøien

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Re: [Theme] Night sky shots
« Reply #374 on: October 30, 2024, 23:34:03 »
Thank you Oivid and Akira for your kind words  :)
 It was windy and some of the 50 captures was not in focus 100% so the stars became unnaturally bigger
The head of the comet also became  light full and not so smooth like Oivids  capture
Oivid did you found Siril more capable than Sequator?

Thanks Nasos, yes Siril is definitely much more capable. The way I have used Sequator has a tendency of blowing out highlights, perhaps increasing contrast too much. The background subtraction is also more advanced in Siril with much more control. It also has a what is called Photometric color calibration which is based on plate solving and database lookup on star colors. (It worked on the comet captures, but I am currently troubling with the plate solving on an old capture of North America Nebula.) If linear results from DSS stacks have been saved in fits files, they can also be further processed in Siril. The advantage is a workflow in linear space that is less prone to mess up colors as when stretching is done in non-linear space (e.g. in CNX2). It is going to take some time getting comfortable with Siril, but forward I think that will be well worth the effort. It is also nice that it is free and open source.
Øivind Tøien