Tales of the unexplained

[Spam]

I took this pic earlier this week and posted it to Facebook in the hopes that some of my scientifically-oriented friends could explain how the swirls came about. Alas, no-one had any idea. Some clues: there was quite a strong on-shore breeze, hence a lot of sand flying about, and there's a lighthouse about 20km away (some of the light in the lower right-hand corner is from that lighthouse, but most of it comes from a beach resort which is 3km away). I'd appreciate any thoughts on the matter.

[Wavelength]

Very nice shot; i like those striations seen in the sky

[proseak]

raw, or Jpeg?

[Spam]

raw, or Jpeg?

Raw, Peter, with some post-processing.

[bnnrcn]

Good question, I wonder about the answer too

[dem]

Were these swirls visible in real life, observed with a naked eye?

Does not look like filter or lens flare. This can be a result of long exposure though. What is the shutter speed? Is this a composite image?

[Spam]

Were these swirls visible in real life, observed with a naked eye?

Does not look like filter or lens flare. This can be a result of long exposure though. What is the shutter speed? Is this a composite image?

Dem, almost nothing in this shot apart from the stars was visible at the time. I'd prefocussed the lens (50mm prime) before sunset and shot at f1.8 for 15 seconds at 100 ISO. It's a single shot. And yes, I'd assume that if it was some kind of flare then the swirls would be circular.

[chauncey]

It's a problem with the light gradient. I can only assume that it wasn't present in the RAW image
or possibly high ISO.

[proseak]

Any chance of uploading the raw file to Dropbox?

[johngunkler]

It looks similar to an overprocessed gradient filter, but I think then the striations would have been concentric circles and then have a recurve to them. Hmmmm.


Sent from my iPhone using Tapatalk

[Spam]

It's a problem with the light gradient. I can only assume that it wasn't present in the RAW image
or possibly high ISO.

Not sure what "problem with the light gradient" might mean. It's not 'visible' in the RAW image, but it is present there when you boost the structure. Shot at 100 ISO.

[Spam]

Any chance of uploading the raw file to Dropbox?

I've put it in Dropbox, Peter (anyone with the link can access it):

https://www.dropbox.com/s/x78efmeimn..._8796.CR2?dl=0

[madcrow]

Haven't a clue what caused it but it's very interesting. Like your image.

[John 2]

It's a problem with the light gradient. I can only assume that it wasn't present in the RAW image
or possibly high ISO.

Simon, is the jpg conversion an 8 bit or a 16 bit file. I think William has the answer. If it's an 8 bit jpg, try converting the RAW image to a 16bit jpg file and see if the problem persists.

[Spam]

Haven't a clue what caused it but it's very interesting. Like your image.

Thanks, Maurice. If I ever reach a point where I can take decent (ie sharp) night shots, I wouldn't mind being able to replicate it.

[Spam]

Simon, is the jpg conversion an 8 bit or a 16 bit file. I think William has the answer. If it's an 8 bit jpg, try converting the RAW image to a 16bit jpg file and see if the problem persists.

John, the streaks were there before I converted to JPG, and, as the techies like to say, it's not a bug it's a feature! I like the effect, and I'd like to know what caused it so I can replicate it.

[george013]

John, the streaks were there before I converted to JPG, and, as the techies like to say, it's not a bug it's a feature! I like the effect, and I'd like to know what caused it so I can replicate it.

You mean just after converting to a raster image, before saving it? And also visible when viewing at 100%?

I like it too.

George

[george013]

I downloaded it and tried to view with IView. It looks like Canon has an embedded full size jpg too, like Nikon.
I don't see those waves. And when playing with brightness etc. in IView they don't turn up.
Maybe time to compare converters?

George

[dem]

It does look like colour posterisation or colour banding.

https://www.cambridgeincolour.com/tu...terization.htm

http://neilvn.com/tangents/post-proc...g-photographs/

[Stagecoach]

Simon,

The banding is a common occurrence when over-processing skies.

The banding was not visible in the CR2 image when first opened in ACR, but becomes apparent once pushing things.

If you take care and keep a watchful eye on the whole image as you undertake any adjustments you can almost avoid it.



If you want to replicate it simply push things up

P.S. just noticed that the file you downloaded was not the same as the one you posted, see bottom detail.