Dear all,
I recently switched from Canon 6D astro-mod to Sony A7III (also astro-mod by irrecams.de). The main reason for the system change was the lenses. Sony FE 20 G is IMHO the best lens for the Milky Way. I made a few shots from a tripod and stacked them - the results are fantastic. A7III is significantly better in terms of noise than the old Canon. However, if I use a tracker and stack 20 - 30 shots, each 30 seconds, I get an ugly circular pattern, which cannot be corrected by bias/flats/darks. Not even GraXpert can correct it.
The issue is well described here https://www.markshelley.co.uk/Astronomy/sony_coloured_polygons.html
It seems to be related only to the lenses recognized by the A7III camera. Manual lenses work fine. But this completely ruins the purpose of a low-light camera combined with a fast, sharp Sony lens.
I tried lens corrections off, and on - both are the same.
I have the latest firmware 4.01 and most probably this is the final one because it hasn't been updated since 2021.
The big question is: has Sony A7IV the same issue, or has it been resolved? There is no point of buying a new camera if the stack of many pictures yields in uncorrectable image.
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One hack I used when cameras were messing up with the image was to turn them off just before finishing the exposure. You might also investigate of there is any hack of the firmware to address the issue, as for Nikons there are aplenty.
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Since you’re shooting with the cam in manual mode, maybe tape off the contacts so that the camera has no idea what lens it is? That should prevent the lens correction artifacts if it really is lens correction artifacts.
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Turn off distortion correction in your menu and turn off ALL aids. I had this issue and its simply from the IBIS, and other automated systems.
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Thanks V.M, I switched the distortion correction, but it didn't help. IBIS was on, so I will give it a try.
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Sean Mc:
Since you’re shooting with the cam in manual mode, maybe tape off the contacts so that the camera has no idea what lens it is? That should prevent the lens correction artifacts if it really is lens correction artifacts.
Then I will not be able to focus, because Sony 20 FE doesn't have a manual focus.
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I managed to take a few tracked pictures (on 2.4.2024 - no Moon), specifically 30x30s, A7III astromod, Sony FE 20 mm G @f2.5 calibrated by 20 bias, 20 flats, and 20 darks. Everything was switched off: lens corrections, stabilization, etc.. My backyard is light polluted, so there was a gradient, which was corrected by GraXpert, then stretched. Otherwise, no other corrections were applied. There are some horizontal dark bands, but this could be caused by light pollution, clouds or so, The ring disappeared, so the mystery was solved. The camera is a keeper.
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The Sony a7 III is absolutely amazing in night photography!
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Jakub Korbel:
I managed to take a few tracked pictures (on 2.4.2024 - no Moon), specifically 30x30s, A7III astromod, Sony FE 20 mm G @f2.5 calibrated by 20 bias, 20 flats, and 20 darks. Everything was switched off: lens corrections, stabilization, etc.. My backyard is light polluted, so there was a gradient, which was corrected by GraXpert, then stretched. Otherwise, no other corrections were applied. There are some horizontal dark bands, but this could be caused by light pollution, clouds or so, The ring disappeared, so the mystery was solved. The camera is a keeper.
Is the electronic curtain on or off? Leaving it on, it may cause some linear banding (caused by artificial light sources). Also check if the bias frames are done correctly. Check stacked image with and without bias.
Im also a proud owner of a modified A7III, it's a beast!
One cool feature: the A7 III is capable of doing full electronic exposures up to 30 seconds. If there are no light sources it is a nice feature, because it is silent and there is no shutter wear  |
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Armin Lukas:
Jakub Korbel:
I managed to take a few tracked pictures (on 2.4.2024 - no Moon), specifically 30x30s, A7III astromod, Sony FE 20 mm G @f2.5 calibrated by 20 bias, 20 flats, and 20 darks. Everything was switched off: lens corrections, stabilization, etc.. My backyard is light polluted, so there was a gradient, which was corrected by GraXpert, then stretched. Otherwise, no other corrections were applied. There are some horizontal dark bands, but this could be caused by light pollution, clouds or so, The ring disappeared, so the mystery was solved. The camera is a keeper.
Is the electronic curtain on or off? Leaving it on, it may cause some linear banding (caused by artificial light sources). Also check if the bias frames are done correctly. Check stacked image with and without bias.
Im also a proud owner of a modified A7III, it's a beast!
One cool feature: the A7 III is capable of doing full electronic exposures up to 30 seconds. If there are no light sources it is a nice feature, because it is silent and there is no shutter wear
Hi Armin, I used the built-in intervalometer and Silent shoot. in Intvl. On. It's completely silent when taking photos, I really like this feature. The darks were taken in the same way, but the flats and bias (darks for flats) were taken by normal shooting. Thanks for pointing this out. I will review the corrected flats. On the other hand, I tried also another lens Sigma 40 EF with an adapter and these bands were not at the same spot, but shifted a lot downwards. I used the same darks and bias, but flats were obviously taken for this lens and shutter setting.
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Jakub Korbel:
Armin Lukas:
Jakub Korbel:
I managed to take a few tracked pictures (on 2.4.2024 - no Moon), specifically 30x30s, A7III astromod, Sony FE 20 mm G @f2.5 calibrated by 20 bias, 20 flats, and 20 darks. Everything was switched off: lens corrections, stabilization, etc.. My backyard is light polluted, so there was a gradient, which was corrected by GraXpert, then stretched. Otherwise, no other corrections were applied. There are some horizontal dark bands, but this could be caused by light pollution, clouds or so, The ring disappeared, so the mystery was solved. The camera is a keeper.
Is the electronic curtain on or off? Leaving it on, it may cause some linear banding (caused by artificial light sources). Also check if the bias frames are done correctly. Check stacked image with and without bias.
Im also a proud owner of a modified A7III, it's a beast!
One cool feature: the A7 III is capable of doing full electronic exposures up to 30 seconds. If there are no light sources it is a nice feature, because it is silent and there is no shutter wear
Hi Armin, I used the built-in intervalometer and Silent shoot. in Intvl. On. It's completely silent when taking photos, I really like this feature. The darks were taken in the same way, but the flats and bias (darks for flats) were taken by normal shooting. Thanks for pointing this out. I will review the corrected flats. On the other hand, I tried also another lens Sigma 40 EF with an adapter and these bands were not at the same spot, but shifted a lot downwards. I used the same darks and bias, but flats were obviously taken for this lens and shutter setting.
Would be interesting to see the result! Then turn on silent shutter and do all calibration frames and see if that works.
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I found the same circular bands in my pictures of comet Pons-Brooks with an A7R III.
If I understand correctly one should turn on silent shutter to prevent them?
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Jakub Korbel:
I managed to take a few tracked pictures (on 2.4.2024 - no Moon), specifically 30x30s, A7III astromod, Sony FE 20 mm G @f2.5 calibrated by 20 bias, 20 flats, and 20 darks. Everything was switched off: lens corrections, stabilization, etc.. My backyard is light polluted, so there was a gradient, which was corrected by GraXpert, then stretched. Otherwise, no other corrections were applied. There are some horizontal dark bands, but this could be caused by light pollution, clouds or so, The ring disappeared, so the mystery was solved. The camera is a keeper.
With the A7III I recommend 50 bias, 50 Darks, and 20 flats. The darks and bias can be reused.
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Federico Lorenzo Barra:
I found the same circular bands in my pictures of comet Pons-Brooks with an A7R III.
If I understand correctly one should turn on silent shutter to prevent them?
Turn off stabilization and auto correction in the settings.
The silent shutter may cause artifacts if there are artificial light sources nearby.
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So, my endeavor continues. I captured the flats in silent mode. I started with Sigma 40 mm [email protected] EF attached by an adapter, ISO 800, lens correction off, and stabilization off.
Now the stack is much better calibrated. Here is how it looks stretched only by STF:
The GraXpert removed the gradient, and no bands or circles, or any other artifacts were visible - I am happy.
Then I switched to Sony 20 mm G [email protected] . Again, I can see that the stack is much better calibrated.
And if I remove the gradient by GraXpert, I get this:
A hideous red-green ring pops up. Just to confirm, lens correction was off, stabilization was off, and all calibration frames were taken in silent mode. I don't know what else to do. However, one has to think about the purpose of this camera. It is definitely not optimal for DSOs and long exposures. A dedicated cooled astro camera is going to do a better job. For Milky Way shots this ring should remain hidden because there is no need to flatten it with GraXpert.
One question remains: does the Sony A7IV combined with this lens suffer from the same background ring?
Could someone do the same exercise with A7IV?
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Jakub Korbel:
So, my endeavor continues. I captured the flats in silent mode. I started with Sigma 40 mm [email protected] EF attached by an adapter, ISO 800, lens correction off, and stabilization off.
Now the stack is much better calibrated. Here is how it looks stretched only by STF:
The GraXpert removed the gradient, and no bands or circles, or any other artifacts were visible - I am happy.
Then I switched to Sony 20 mm G [email protected] . Again, I can see that the stack is much better calibrated.
And if I remove the gradient by GraXpert, I get this:
A hideous red-green ring pops up. Just to confirm, lens correction was off, stabilization was off, and all calibration frames were taken in silent mode. I don't know what else to do. However, one has to think about the purpose of this camera. It is definitely not optimal for DSOs and long exposures. A dedicated cooled astro camera is going to do a better job. For Milky Way shots this ring should remain hidden because there is no need to flatten it with GraXpert.
One question remains: does the Sony A7IV combined with this lens suffer from the same background ring?
Could someone do the same exercise with A7IV?
Could you share a stack of the second photo without flats?
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Yes, this is what I was thinking, so I did the stack only with darks, no flats, no bias.
Here is the picture just stretched by STF, vignetting is visible:
GraXpert applied, stretched:
I also tried without the darks, but it was the same.
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Jakub Korbel:
Yes, this is what I was thinking, so I did the stack only with darks, no flats, no bias.
Here is the picture just stretched by STF, vignetting is visible:
GraXpert applied, stretched:
I also tried without the darks, but it was the same.
I also own the combo Sony A7 III and the Sony 20mm 1.8 G Lens, but did not see any rings. Have you tried F/2.8 or higher?
When i get the chance i can try the exact same settings as you. A list of the important settings would be good. Then I can get back to you |
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Good luck with that Armin. I did the star test and the stars had a small "wing" up to f2.2, at 2.5 it disappeared, so I set this f-number for long exposures.
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Here is a sample:
Sony A7 III
Sony 20mm 1.8 @ 2.8
ISO 800
Single Frame no calibration, after background extraction
I am not sure if I used silent shutter, but no rings at all.
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This is just a single frame, mine is a stack of 30 frames, so maybe this ring cumulates.
I took a single frame and applied GraXpert:
The ring is almost invisible.
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Jakub Korbel:
This is just a single frame, mine is a stack of 30 frames, so maybe this ring cumulates.
I took a single frame and applied GraXpert:
The ring is almost invisible.
I also checked other photos after stack (21 frames), and again no circular ring.
I would try to test different aperture settings and also turn off silent shutter.
If that doesnt work, maybe there is an issuse with the lens.
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Jakub Korbel:
This is just a single frame, mine is a stack of 30 frames, so maybe this ring cumulates.
I took a single frame and applied GraXpert:
The ring is almost invisible.
I found more info about the circular banding. Have you checked if you are shooting in uncompressed RAW? It seems to be an in-camera correction. Other than that it could be activated by an internal correction after putting on the Sony lens.
BTW: Which firmware are you on?
https://www.sonyalphaforum.com/topic/12419-sony-a7iii-posterization-and-colored-banding/
https://www.dpreview.com/forums/post/62015842
https://www.dpreview.com/forums/post/62010566 |
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Armin Lukas:
Jakub Korbel:
Yes, this is what I was thinking, so I did the stack only with darks, no flats, no bias.
Here is the picture just stretched by STF, vignetting is visible:
GraXpert applied, stretched:
I also tried without the darks, but it was the same.
I also own the combo Sony A7 III and the Sony 20mm 1.8 G Lens, but did not see any rings. Have you tried F/2.8 or higher?
When i get the chance i can try the exact same settings as you. A list of the important settings would be good. Then I can get back to you
This is a very timely thread which I am following closely as I have just started to use the a7iii and 20mm f1.8 G lens.
As mentioned above it would be good to have a list of settings that yield the best results.
My understanding is the following - please correct or add to as appropriate:
- Uncompressed RAW selected
- LENR -> off
- High ISO NR -> off (normally shoot at low ISO but belt and braces)
- Lens Comp. -> all off
- Intvl. Shoot. Func. -> Silent Shoot. in Intvl. off
- White Balance -> Daylight or Custom if modded
- MF assist -> off
- Anti-flicker shoot -> off
- Silent Shooting -> off
- e-Front Curtain Shutter -> on (Not sure about this!!??!)
- SteadyShot -> off
Please let me know what is wrong and/or incomplete.
Also I haven addition to the Sony 20mm f1.8 G, a Viltrox 16mm f1.8. Both yield similar quality images - the latter seems to be just as sharp as the Sony with possibly fewer aberrations. I have been looking at star field images in Pixinsight. In both cases, BlurXterminator does a great job of dealing with most but not all of the defects.
Could someone please make available some RAW files for me to compare my copy of the Sony 20mm against? I have the feeling that my copy is not as good as some of those reviewed on Youtube?
Thanks in advance.
Des
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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...
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