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Bryan

Banding in a sky

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I was fortunate to capture a rainbow across the sky above the town of Berwick. Unfortunately, in the raw images, there appears to be bands running across the sky more or less at right angles to the line of the rainbow. Processing the photo the effect is magnified. I suspect that this a camera fault (Sony a6500, Olympus 50mm lens, ISO 100) but there is just a chance that it is a natural phenomenon. I've not noticed this before with this or any other camera. Not uploaded as I fear it may result in a QC fail. Any thoughts?

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I've had this on exporting to JPEG (and if subtle enough Alamy do seem to allow it through). But not in RAW. It suggests that your camera is compressing the RAW file, something that is known in other Sonys. However it could be a software/colour space issue. What software are you using? Check what the working colour space is; ProPhoto is usually recommended for editing and is used in Lightroom (although Adobe RGB would show the effects on the output file better). Then take steps to reduce banding by keeping the sky colour within the available gamut - back off saturation, tweak white balance, tweak the HSL sliders until it looks more natural. You can also add colour to smooth out the bands, or a small amount of local fine grain to 'dither' the colour across them.

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It may not be your problem (banding) but there have been reports of grid artifacts (appears as parellel/grid lines) on Fuji, Sony and maybe other mirrorless cameras, usually with backlit subjects. They can be visible in the viewfinder and are highly dependent on viewing angle, a small change eliminates them. It is a hardware issue apparently, Fuji improved things by changing the shape of the edges of the body aperture behind the lens apparently. I have not noticed it on my early model Fuji X-T1 and X-T2 that can apparently produce it.

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Posted (edited)

I don't think we're going to find out without seeing the image, and I don't think this is it, but Sony RAWs are compressed and it can give rise to striping artifacts.

https://www.dpreview.com/articles/2834066212/the-raw-and-the-cooked-pulling-apart-sony-raw-compression

I've seen it at high-contrast edges but it's only really noticeable at 200%. As I said I don't think this is Bryan's issue.

Edited by spacecadet

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Posted (edited)

Thanks for the responses all!

 

It's nothing as pronounced as in that lovely image posted by Vincent, but the bands are probably radial.

 

It doesn't look like the problem referred to by Mark, the bands are more extensive.

 

If I get the time I'll try to upload an actual pixels  section to Flickr.

 

I am using LR to process the image.

Edited by Bryan

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Posted (edited)

I've uploaded the photo to Flickr

 

Hopefully you can see it here  Photo  - If this doesn't work I'll use my blog.

 

Edit - I removed the actual pixels crop

Edited by Bryan

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Looks natural to me. Camera fixed pattern noise is usually parallel to the sensor edge.

  • Upvote 2

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Posted (edited)

Looks "natural" to me too. I don't think that QC would have a problem with the bands. They certainly don't fit the reasons for failure criteria. But please don't quote me. B)

 

P.S. Could be just rain / moisture bands. No?

Edited by John Mitchell
  • Upvote 2

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Thanks Mark and John, I'll risk an upload and see what transpires.

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I believe it is the falling rain near the rainbow catching some light. By tilting the screen on my laptop I can make out the streaks clearly, and they look just like distant rain to me.

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I agree, it looks natural. However the crop shows some compression/colour space artefacts in the form of purple blotches. 

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Just to bring this to a conclusion, I uploaded the image in a small batch of three and they passed QC. Keyworded this evening.

 

Thanks for all the responses!

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I too am in agreement with the others.  Looks like a nice rainbow photo to me.  Looks natural.  I don't think you'll have a problem.  It pays to have a camera with you.

 

Rick

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