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andromeda stacked final result in siril

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#26 vidrazor

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Posted 25 February 2024 - 12:23 PM

 In any case 60 secs at iso 800 should correspond to my 30 secs at f/4

Well, the bottom line is his subs are blown out. He needs to drop exposure.
 


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#27 srvkmr

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Posted 25 February 2024 - 12:26 PM

Gentlemen, please don't waste more time on this project. Tonight I collected fresh calibration frames but the result didn't improve. I will collect fresh lights in next winter.



#28 vidrazor

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Posted 25 February 2024 - 03:07 PM

Gentlemen, please don't waste more time on this project. Tonight I collected fresh calibration frames but the result didn't improve. I will collect fresh lights in next winter.

Well you'd be shooting under a full moon. Wait till new moon before trying again, and look at nearby light sources.
 



#29 Catchlight

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Posted 26 February 2024 - 12:00 AM

Gentlemen, please don't waste more time on this project. Tonight I collected fresh calibration frames but the result didn't improve. I will collect fresh lights in next winter.

Suit yourself, but I would say with the conditions and data you have described, there should be potential to create a good image. If it were my data I would be interested in understanding and resolving the problem, to either salvage the data and get an image or avoid the problem in the future. Do you have the original raw files direct from the camera? Do they appear as overexposed as the files you have posted? As mentioned I shot in similar conditions (bortle 6, full moon) and a single light frame straight from the camera looks like this:
gallery_443568_25640_81000.jpg


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#30 sharkmelley

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Posted 26 February 2024 - 01:12 AM

Do you have the original raw files direct from the camera? 

See post #18


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#31 srvkmr

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Posted 26 February 2024 - 12:50 PM

I had already opened those files in Pixinsight. But the light is not an original raw file from his Nikon camera, it's a fits file, I assume created by the Asiair, which is why I made the comment, and since we both made  made very similar exposures with matching settings and full moon, I am merely suggesting there might be something else wrong. If it were my setup I would want to know what the problem was before wasting another session, or potentially salvaging the data and getting a usable image...

I do not have any raw files directly from nikon camera. I only have fits from asiair. Previously I used fits from asiair and calibration frames shot in raw from camera (later converted to fits to stack in siril). As a result, my flats didn't merge with the original fits created through ASIAIR. So I had to retake the calibration frames through asiair.

This time I didn't repeat that mistake.

I also retook calibration frames in order to iron out any discrepancy in previous calibration frames.

I can see a glimpse of the galaxy along with some stars in a single fit file (opened in GIMP). But somehow something is going wrong with either the stacking or the local external light source is creating some issue because after one hour shoot, the subject was closer to the horizon.

In order to check any problem with stacking, I stacked the images in deep sky stacker but it didn't give any good results.

I value your suggestions.

Yes I am eager to know the issue and I want to solve it but I am running out of options.

If you still have any weapon left in your arsenal, I am ready to do experiment with this project.



#32 srvkmr

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Posted 26 February 2024 - 12:52 PM

Suit yourself, but I would say with the conditions and data you have described, there should be potential to create a good image. If it were my data I would be interested in understanding and resolving the problem, to either salvage the data and get an image or avoid the problem in the future. Do you have the original raw files direct from the camera? Do they appear as overexposed as the files you have posted? As mentioned I shot in similar conditions (bortle 6, full moon) and a single light frame straight from the camera looks like this:
gallery_443568_25640_81000.jpg

Your single image looks much cleaner than my single image at 60 sec exposure. Also I see that your image has more stars than mine. Did you use 600mm focal length as I could read on the left top of this image?



#33 Catchlight

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Posted 26 February 2024 - 11:15 PM

Your single image looks much cleaner than my single image at 60 sec exposure. Also I see that your image has more stars than mine. Did you use 600mm focal length as I could read on the left top of this image?

yes 600mm f/4, 30 secs iso800, lightpollution map says we are well inside bortle 6, so I would expect your 60 sec image at f/5.6 to be similar.
That said I had one session recently where there were very thin high clouds, not visible to the naked eye, but enough to wash out the subs and make them unusable. 


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#34 srvkmr

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Posted 28 February 2024 - 11:37 AM

yes 600mm f/4, 30 secs iso800, lightpollution map says we are well inside bortle 6, so I would expect your 60 sec image at f/5.6 to be similar.
That said I had one session recently where there were very thin high clouds, not visible to the naked eye, but enough to wash out the subs and make them unusable. 

Seeing your focal length, I have a question in mind. Last time I clicked M31 using only tripod, I used 200 mm focal length. Redcat 51 users click andromeda and it has 250mm focal length. How did you get a full picture of andromeda at 600 mm focal length?



#35 Catchlight

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Posted 28 February 2024 - 11:32 PM

Seeing your focal length, I have a question in mind. Last time I clicked M31 using only tripod, I used 200 mm focal length. Redcat 51 users click andromeda and it has 250mm focal length. How did you get a full picture of andromeda at 600 mm focal length?

Full frame sensor and very little cropping, but it's still a pretty tight fit, even shot diagonally. Pixinsight shows the actual focal length at 580mm, so maybe the Canon 600/4 is actually 580...



#36 vidrazor

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Posted 29 February 2024 - 03:18 AM

Full frame sensor and very little cropping, but it's still a pretty tight fit, even shot diagonally. Pixinsight shows the actual focal length at 580mm, so maybe the Canon 600/4 is actually 580...

580? i know lenses are never the listed focal length, but that's long way from home. grin.gif



#37 Catchlight

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Posted 29 February 2024 - 04:01 AM

580? i know lenses are never the listed focal length, but that's long way from home. grin.gif

My mistake, Pixinsight shows 582.4   but I also found this on a DPreview forum that says 592, so it does seem the 600/4 is around 1-3% shorter :):

 


Just out of curiosity, I measured the front element diameter as this is essentially the same as the entrance pupil size for a long lens. 141 mm. So using the f/4.2 value (and I realise this, too, is only an approximation) we have 141 * 4.2 = 592 mm. Doesn't prove anything, it's just interesting to note.



#38 vidrazor

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Posted 29 February 2024 - 11:10 AM

My mistake, Pixinsight shows 582.4   but I also found this on a DPreview forum that says 592, so it does seem the 600/4 is around 1-3% shorter smile.gif:

Just out of curiosity, I measured the front element diameter as this is essentially the same as the entrance pupil size for a long lens. 141 mm. So using the f/4.2 value (and I realise this, too, is only an approximation) we have 141 * 4.2 = 592 mm. Doesn't prove anything, it's just interesting to note.

582.4 is still a long way from home. :)
 




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