Jakub Korbel:
Dear all,
I have the following settings:
Firmware: Ver. 4.01 (latest) Lens Ver. 01
Raw file type Uncompressed
ISO was always set to 800, for all lights, bias, and darks.
Long Exposure NR Off
High ISO NR Off
Color Space sRGB
Lens Comp. all Off
Interval Shooting On, Silent Shoot. in Intvl. On
White Balance - Custom, because it's astro-modified camera
DRO Off
Picture Effect Off
Picture Profile Off
Manual focus, assist On
SteadyShot Off
Viltrox 16mm f1.8 looks very good, so I am thinking of selling the 20mm and hoping for the ring-less images... I would try two more things: - turn off electronic shutter and try the pure mechanical (no e-curtain) - Set the year to 2037, restart the camera and set back to 2024 (the camera performs a pixel mapping)
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OK, just did the pixel mapping. Now I have to wait for cloudless/Moonless night. I am going to try f2.8 as well.
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Jakub Korbel:
Dear all,
I have the following settings:
Firmware: Ver. 4.01 (latest) Lens Ver. 01
Raw file type Uncompressed
ISO was always set to 800, for all lights, bias, and darks.
Long Exposure NR Off
High ISO NR Off
Color Space sRGB
Lens Comp. all Off
Interval Shooting On, Silent Shoot. in Intvl. On
White Balance - Custom, because it's astro-modified camera
DRO Off
Picture Effect Off
Picture Profile Off
Manual focus, assist On
SteadyShot Off
Viltrox 16mm f1.8 looks very good, so I am thinking of selling the 20mm and hoping for the ring-less images... Hi, Please see: https://www.markshelley.co.uk/Astronomy/camera_summary.htmlThis lists known problems for a range of cameras and is an amazing piece of work. For Sony, my understanding is that the best bets are the A7RV and A7CII. Fingers crossed for the A7V when it comes out. It also seems clear that certain artefacts, eg coloured concentric polygons, may occur with any CPU lens (i.e. one that has a chip). This might mean that switching from Sony to Viltrox will not solve this particular problem. I intend to mainly use my A7III for wide-field Milky Way imaging. For this application as I believe you have already noted, there is less chance of encountering some artefacts as the images are in general not heavily underexposed. For DSO imaging I am intrigued to see how well an astro modded A7III can do when coupled with a small refractor like the redcat 51. It has after all the same sensor as the ASI2400 which has a great reputation. Cheers, Des
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I had a clear evening and had a chance to test the pixel re-mapping before the Moon rose. Honestly, I didn't expect much. As suggested by Armin I tried F2.8. Here is a stack of 30x30s, Sony 20 mm G, ISO 800, F2.8, all electronic aids switched off, calibrated by darks, bias, and flats at F2.8 silent mode.  Applied GraXpert, stretched, and the ring...  ...disappeared. Then I wanted to shoot F2.5 or F1.8, but the clouds rolled in and ruined further experiments. I cannot tell, whether this improvement was caused by pixel mapping or just by the aperture F2.8. I am going to test it next time. @Armin Lukas thank you for the hints!
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Jakub Korbel:
I had a clear evening and had a chance to test the pixel re-mapping before the Moon rose. Honestly, I didn't expect much.
As suggested by Armin I tried F2.8.
Here is a stack of 30x30s, Sony 20 mm G, ISO 800, F2.8, all electronic aids switched off, calibrated by darks, bias, and flats at F2.8 silent mode.
Applied GraXpert, stretched, and the ring...
...disappeared.
Then I wanted to shoot F2.5 or F1.8, but the clouds rolled in and ruined further experiments.
I cannot tell, whether this improvement was caused by pixel mapping or just by the aperture F2.8. I am going to test it next time.
@Armin Lukas thank you for the hints! Nice! Im happy you have see improvements. It could the the aperture of F/2.5, which is cauing the circlular artefacts. Hopefully all rings are gone!
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Jakub Korbel:
...disappeared. I am not sure if that's true; I'm seeing a dark crescent towards the bottom left corner. I am also not sure if GraXpert is the proper tool for gradient removal in this case. My workhorse for such tests is ABE. Furthermore, I don't know if GraXpert was trained in such wide fields and I don't know how accurate you were while taking flats. For the last two sources of uncertainty I can not say that your issue has disappeared. Sorry for being pessimistic  |
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The crescent at the bottom left corner is not centered compared to the pattern rings reported previously. I would say, this is caused by light pollution of my Bortle 5 sky.
But you are right. I should test it somewhere dark, and then conclude…
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In case you haven't, check these out: https://www.markshelley.co.uk/Astronomy/Articles.htmlIn short, it's the camera.
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The last experiment - comparison of F2.5 vs F2.8. Sony A7III astro mod., Sony 20mm FE ISO 800 Lens correction - off Stabilization - off Silent mode 20x 30s, calibrated by bias, flats, and darks, all captured in silent mode. Stacked. Flattened by good old DBE. Stretched. Here is F2.5  The green ring is obvious, the pixel re-mapping didn't help. F2.8  There is still a slight sign of the ring, but this is useable. Conclusion: A7III combined with Sony 20 mm FE must be slowed down to F2.8, then it works well.
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Wei-Hao Wang:
In case you haven't, check these out:
https://www.markshelley.co.uk/Astronomy/Articles.html
In short, it's the camera. It's incredible that such good cameras can show these defects..
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Jakub Korbel:
Dear all,
I have the following settings:
Firmware: Ver. 4.01 (latest) Lens Ver. 01
Raw file type Uncompressed
ISO was always set to 800, for all lights, bias, and darks.
Long Exposure NR Off
High ISO NR Off
Color Space sRGB
Lens Comp. all Off
Interval Shooting On, Silent Shoot. in Intvl. On
White Balance - Custom, because it's astro-modified camera
DRO Off
Picture Effect Off
Picture Profile Off
Manual focus, assist On
SteadyShot Off
Viltrox 16mm f1.8 looks very good, so I am thinking of selling the 20mm and hoping for the ring-less images... Hello Jakub, following this thread as I'm interested in getting a Sony A7 III or IV and astro mod it, to shoot the milky way. Have you been able to conduct more experiment and come to a conclusion on your issue ? In the settings you mentioned above, I noticed you used the sRGB color space - have you tried Adobe RGB which is supposed to be a larger color space ?
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Hi Vedelou, I concluded that if I slow down sony 20mm to f2.8, the ring disappeared. What I heard A7iv doesn't suffer from it, so if you hesitate between iii and iv, get iv. However I will keep using my iii and the lens slowed down to f2.8
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Hi I've now posted three images with a A7iii and the Viltrox 16mm f1.8 see https://www.astrobin.com/users/desmc/ (the most recent MW shots). These are all stacked images of individual 30s or 10s subs. There are definitely artefacts present if one pushes the background too hard but otherwise I think it is possible to get reasonable images with this combination. Cheers, Des
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