38 replies to this topic

[Joooop]

It's nothing to do with red-eye removal.

 

The rings are definitely related to those steps in the histogram.  All of your lights have those histogram steps except the one that is 25sec and the one that is ISO 200.  None of your ISO 200 flats had the steps.  I'm beginning to think that only long exposures at higher ISO are affected. 

 

If you want to test this then do the following:

• 25sec, 30sec, 45sec exposures at ISO 200
• 25sec, 30sec, 45sec exposures at ISO 400
• 25sec, 30sec, 45sec exposures at ISO 800

In each case adjust the aperture so the histogram peak is halfway or less.  As always, I'm happy to examine them.

 

Mark

Ahh alright, good to know!

Skies just cleared up so hopefully i can get a few of each of these as well as some 23mm tests.

Thank you so much for all of your help, really.
 

[Joooop]

It's nothing to do with red-eye removal.

 

The rings are definitely related to those steps in the histogram.  All of your lights have those histogram steps except the one that is 25sec and the one that is ISO 200.  None of your ISO 200 flats had the steps.  I'm beginning to think that only long exposures at higher ISO are affected. 

 

If you want to test this then do the following:

• 25sec, 30sec, 45sec exposures at ISO 200
• 25sec, 30sec, 45sec exposures at ISO 400
• 25sec, 30sec, 45sec exposures at ISO 800

In each case adjust the aperture so the histogram peak is halfway or less.  As always, I'm happy to examine them.

 

Mark

Just got in from shooting some test lights in between the clouds and wind. I did the tests you listed here while also trying different aperture stops for each for my own use to take a look at star shapes (f/4.8, 5.6, 6.4, 7.1, 8.0) and also did 2-3 shots at each exposure setting since it was windy and I wanted the best star shapes possible for my own comparing.

Unfortunately, either my brain completely slipped over the night or I lost some files in the transfer (my card reader disconnected after starting the transfer somehow and I decided to cut the files onto my PC instead of just copying them then deleting afterwards...). After looking at my files now, I noticed holes in the exposure configurations

I ended up with just:

• 25sec, 30sec @ ISO 200
• 25sec, 30sec @ ISO 400
• 25sec, 45sec @ ISO 800
   

I have absolutely no idea how those holes occurred, with the way I was carefully going through each exposure setup.

I also got the following lights from my 23mm F/2 lens:

• 5sec, 15sec, 30sec @ ISO 200 & F/3.2
• 5sec, 15sec, 30sec @ ISO 400 & F/3.2
• 5sec, 15sec, 30sec @ ISO 800 & F/3.2
• 5sec, 15sec, 30sec @ ISO 1600 & F/3.2
   

So with the 200mm blunder aside, here is everything listed above: https://drive.google...iew?usp=sharing

Looks like I'll have clear skies on Monday so I can fill in the holes here if necessary at that point.

[sharkmelley]

So with the 200mm blunder aside, here is everything listed above: https://drive.google...iew?usp=sharing

 

Thanks for files. First of all it's worth pointing out that none of these files showed the problem (i.e. the steps in the histogram) anywhere near as badly as your earlier sets. There are a few points of interest.

 

The file 23mm_ISO800_15.0sec at f -3.2.RAF shows slight steps in the histogram.  This shows that shorter exposures can be affected but I couldn't force any rings to appear.

 

The most badly affected file was 200mm_ISO800_45.0sec at f-4.8.RAF but it was only just possible to make the rings appear.

 

None of the ISO 200 exposures showed any problem but their histograms were all further to the left.  Maybe this underexposure helps prevent the problem.

 

One interesting observation is that Orion-f6.4_iso800_60sec.RAF from the earlier set had a big problem but 200mm_ISO800_45.0sec at f -6.4.RAF from the new set has hardly any problem.  But there's only a slight difference in exposure length.  I don't understand this at all.

 

From the evidence we've seen so far I think your best shooting strategy is to use lower ISOs i.e. ISO 200, 400, 800 with exposure times of 30sec or less.  But this is only a tentative conclusion because we have so little understanding of what is going on.

 

Mark

[Joooop]

Thanks for files. First of all it's worth pointing out that none of these files showed the problem (i.e. the steps in the histogram) anywhere near as badly as your earlier sets. There are a few points of interest.

 

The file 23mm_ISO800_15.0sec at f -3.2.RAF shows slight steps in the histogram.  This shows that shorter exposures can be affected but I couldn't force any rings to appear.

 

The most badly affected file was 200mm_ISO800_45.0sec at f-4.8.RAF but it was only just possible to make the rings appear.

 

None of the ISO 200 exposures showed any problem but their histograms were all further to the left.  Maybe this underexposure helps prevent the problem.

 

One interesting observation is that Orion-f6.4_iso800_60sec.RAF from the earlier set had a big problem but 200mm_ISO800_45.0sec at f -6.4.RAF from the new set has hardly any problem.  But there's only a slight difference in exposure length.  I don't understand this at all.

 

From the evidence we've seen so far I think your best shooting strategy is to use lower ISOs i.e. ISO 200, 400, 800 with exposure times of 30sec or less.  But this is only a tentative conclusion because we have so little understanding of what is going on.

 

Mark

Thank you so much, Mark. These are really interesting results for sure.

I'll give the 30sec strategy a shot on monday, even if i'll be drowned out by a close to full moon that night. Might start with 800 ISO and go from there.

I'll also update this thread with the holes in those tests if I can. Just so the full range is available.
 

[Joooop]

Thanks for files. First of all it's worth pointing out that none of these files showed the problem (i.e. the steps in the histogram) anywhere near as badly as your earlier sets. There are a few points of interest.

 

The file 23mm_ISO800_15.0sec at f -3.2.RAF shows slight steps in the histogram.  This shows that shorter exposures can be affected but I couldn't force any rings to appear.

 

The most badly affected file was 200mm_ISO800_45.0sec at f-4.8.RAF but it was only just possible to make the rings appear.

 

None of the ISO 200 exposures showed any problem but their histograms were all further to the left.  Maybe this underexposure helps prevent the problem.

 

One interesting observation is that Orion-f6.4_iso800_60sec.RAF from the earlier set had a big problem but 200mm_ISO800_45.0sec at f -6.4.RAF from the new set has hardly any problem.  But there's only a slight difference in exposure length.  I don't understand this at all.

 

From the evidence we've seen so far I think your best shooting strategy is to use lower ISOs i.e. ISO 200, 400, 800 with exposure times of 30sec or less.  But this is only a tentative conclusion because we have so little understanding of what is going on.

 

Mark

Hey again Mark, hope you're well.

Back again to just update ya after last nights attempt. I went for the rosette nebula with these settings:
 

• 30" Lights (~300 total, DSS decided to use ~210 since my framing was wonky throughout the night. I might try and re-stack tonight to utilize more data).
• ISO 400
• Aperture 7.1
• Bortle 8-9, Waning gibbous moon
   

Unfortunately the rings are still present:

 

Luckily this target was centered so I was able to (over) edit and crop a lot to get my first decent AP result:

 

Here is a zip with a light, a flat, the autostretch and a png of sirils autostretch (though I realize you're only interested in the RAW files): https://drive.google...iew?usp=sharing

At this point I'm kind of at a loss. Before I was considering upgrading this lens to a longer zoom lens but I think I might pivot and just invest in a starter telescope. At that point I could find out if its a camera or lens issue right now, haha.

[sharkmelley]

Hey again Mark, hope you're well.

Back again to just update ya after last nights attempt. I went for the rosette nebula with these settings:
 

• 30" Lights (~300 total, DSS decided to use ~210 since my framing was wonky throughout the night. I might try and re-stack tonight to utilize more data).
• ISO 400
• Aperture 7.1
• Bortle 8-9, Waning gibbous moon
   

Unfortunately the rings are still present:

 

 

Luckily this target was centered so I was able to (over) edit and crop a lot to get my first decent AP result:

 

Here is a zip with a light, a flat, the autostretch and a png of sirils autostretch (though I realize you're only interested in the RAW files): https://drive.google...iew?usp=sharing

At this point I'm kind of at a loss. Before I was considering upgrading this lens to a longer zoom lens but I think I might pivot and just invest in a starter telescope. At that point I could find out if its a camera or lens issue right now, haha.

The artefacts you are seeing this time are entirely different - there are no coloured rings in your raw light, raw flats or the Autosave.tif.  Looking at the histograms of the raw files in RawDigger there are also no steps in the histograms, which is really good news.

 

Yes there are artefacts in the stacked data but these variations in brightness (not in colour) are probably caused by uneven illumination in your lights (maybe stray light from the moon?) or in the flats.

 

Mark

[Joooop]

Ahh okay, I was zeroing in on the very edges of the corners since I saw some blue and green casting there.

Would it be safe to say this is just a byproduct of the zoom lens optics? I feel like my flats should be working to correct the dark ring I keep getting. I should do a test stack of this data without lights like I did in my OP here, since that mostly avoided the ring but gave me bad vignetted corners instead (which I feel would be easier for me to remove in post). I've been really careful to not alter anything on the lens / camera between light acquisition and flat acquisition.

Would a test night without my lens hood be useful to gather info? I feel like a light shield like that could only help matters but I'm willing to mix up any variables I can.

[sharkmelley]

Maybe you are referring to what's happening in each corner here in this very saturated version:

 

 

Fuji's internal raw processing treats the corners differently to the rest of the frame.  You can see it clearly in your raw flat which I opened in Photoshop and dialed the saturation up high:

 

 

Although there are no concentric coloured rings, it seems to be the case that the internal raw processing causes the corners to not calibrate correctly.  

 

Mark

[vidrazor]

As an aside to all this, I may want to suggest not shooting on a rooftop. Houses and buildings flex and move more than you think. I don't think that's adding to this problem, but I've had motion problems shooting on rooftops that went away on solid ground.

Edited by vidrazor, 02 April 2021 - 09:32 PM.

[ribuck]

Hi all, was there any resolution to this problem as I’m facing what appears to be similar issues with my Fuji XF 16-80mm lens where I see a similar ring patter in my individual raw images but not in my flats.

 

in my case I know it’s not a stacking artefact, as the ring appears in my individual raw images.

 

 

 

[sharkmelley]

Hi all, was there any resolution to this problem as I’m facing what appears to be similar issues with my Fuji XF 16-80mm lens where I see a similar ring patter in my individual raw images but not in my flats.

 

in my case I know it’s not a stacking artefact, as the ring appears in my individual raw images.

It's an issue with the camera's internal raw data processing and not a lens issue.  Some Fuji models have this problem while others do not.  Which camera are you using?

[ribuck]

It’s a Fuji x-s10. Do you know if there Is there some way to disable it or is it something that is baked into the processing that cannot be changed ?

[sharkmelley]

It’s a Fuji x-s10. Do you know if there Is there some way to disable it or is it something that is baked into the processing that cannot be changed ?

I have no information on the Fuji X-S10 but the Fuji cameras I have investigated are listed here:

https://www.markshel...y.html#Fujifilm

 

I am always happy to examine example raw files to determine if it is the same problem.  However, if it is the usual Fuji problem then it is baked into the processing and cannot be changed unless Fuji decides to release a camera firmware update addressing the issue.

[ribuck]

H sharkmelley, I’ll see if I still have the original raw files. Very much appreciate the offer to look at them. The X-S10 shares the same sensor and electronics and the XT4, likely to be the same issue.

 

I wouldn’t even know how to approach Fuji with such an issue.