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02-09-2016, 05:44 PM   #16
GUB
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Yes -- the op images were 28mm @ f2.8 and I think your blue tak would just show there judging by my 28mm. The interference pattern would have to be knife sharp though but I guess that might be possible given a single wavelength of light. And if the issue is indeed out on a filter then that sharpens things a little.

---------- Post added 02-10-16 at 01:53 PM ----------

QuoteOriginally posted by Digitalis Quote
the interference pattern would also need a second monochromatic light source out of phase with the primary light source to create the interference
Could this actually be the case? The Aurora after all is not a solid surface of light.

02-09-2016, 06:00 PM   #17
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QuoteOriginally posted by GUB Quote
Could this actually be the case? The Aurora after all is not a solid surface of light.
The Aurora emits monochromatic green 557.7 nm light. The aurora emits very specific frequencies of light depending on the atoms being excited, but it would have to change extremely fast for this kind of interference to occur. Also Rayleigh scattering would reduce the amplitude of the phase differential.

The spectral range of the aurora:
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Last edited by Digitalis; 02-10-2016 at 05:19 AM.
02-10-2016, 02:57 AM   #18
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I don't know about the rest of you, but I find this " stuff " fascinating. I have got ssooooo much to learn.
02-10-2016, 03:19 AM   #19
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I think the OP's got more than they bargained for here - fascinating stuff !

02-10-2016, 03:58 AM   #20
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A quick search on the internet yielded some other people who've had very, very similar results when taking aurora photos... interesting...

EDIT: At least one example was seen using a 35mm film camera. So the OP's problem is unlikely to be sensor-related.
02-10-2016, 05:15 AM   #21
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QuoteOriginally posted by BigMackCam Quote
So the OP's problem is unlikely to be sensor-related.
Which is what I have been saying all along, thanks for the link BMC.
02-10-2016, 12:50 PM   #22
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Yes I felt totally shot down when I realized one of my links was using film-
Aurora, Aurora Borealis, Northern Lights
So as one of the posters in your link says;
The real mystery is why the rings are so perfectly focused on the film plane.
Taking Digitalis' blu tak image - there has to be 4-6 rings visible resolved in the total space of his blue tak.
The op image was 28mm@2.8 so it would have had even a shallower dof.
Here is an image of a black 5-13mm washer on a filter screwed on to my M28 3.5 @3.5. The filter appears to be about 4mm in front of the element.That is about as sharp as you are going to get on or against a lens. Once more you need to resolve 4-6 rings in the central clear area to replicate the effect. If it is an artifact it is going to be visible to the naked eye otherwise it has to be an effect like airy disks from the edge of the aperture.
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02-10-2016, 01:04 PM   #23
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I'm so out of my depth here, it isn't funny!

Is it possible there is something in the way coatings are applied somewhere in the optical path of the lens, or the way the lens elements are ground, and the frequency of light in an aurora situation? When I saw the rings in the centre of the image, the first thing it reminded me of was a fresnel lens. Aren't fresnel optics still used in certain camera lenses?

Apologies for the dumb comments, I've followed the thread so far and will continue to do so, but it's just way above my head

02-10-2016, 01:20 PM   #24
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QuoteOriginally posted by BigMackCam Quote
I'm so out of my depth here, it isn't funny!
I know what you mean
I just hope Digitalis starts picking on you rather than me
02-10-2016, 01:28 PM   #25
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QuoteOriginally posted by GUB Quote
I know what you mean
I just hope Digitalis starts picking on you rather than me
"Destroying" is such a harsh term... Let's just say he was "picking on" you...
02-10-2016, 01:36 PM   #26
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QuoteOriginally posted by BigMackCam Quote
"Destroying" is such a harsh term... Let's just say he was "picking on" you...
Yeah leave me some pride
02-10-2016, 01:41 PM   #27
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QuoteOriginally posted by GUB Quote
Yeah leave me some pride
Will do

I have lenses and Blu-Tak here, if I can do anything to help. Oh, and some spearmint gum, too... I can stick things on lenses *reeeaaalll* good!
02-10-2016, 01:56 PM   #28
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QuoteOriginally posted by BigMackCam Quote
Will do

I have lenses and Blu-Tak here, if I can do anything to help. Oh, and some spearmint gum, too... I can stick things on lenses *reeeaaalll* good!
Actually "North East of England" would put you in a spot where you can see the Aurora wouldn't it? The least you can do is go out at night and wait for it and do some objective experimenting!!
Here in the North Island of NZ I have only seen the southern lights a couple of times and they were vague and colourless.
02-10-2016, 02:12 PM   #29
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QuoteOriginally posted by GUB Quote
Actually "North East of England" would put you in a spot where you can see the Aurora wouldn't it? The least you can do is go out at night and wait for it and do some objective experimenting!!
Well, the more northern parts of Scotland are the best for UK viewing, as I understand it - though we *can* occasionally see it from areas of Northumberland, just a little further north of where I live... But it's cold and wet here right now - so my offer of lenses, Blu-Tak and spearmint gum stands!
02-10-2016, 02:29 PM - 1 Like   #30
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QuoteOriginally posted by pjv Quote
Hi Mrbossman. In the " search the forums " box, type in Newton's rings.
No, this is NOT Newton rings. Newton rings are uneven and require contact between two surfaces. The phenomena you see in these pictures show rings distributed form the optical axis being gradially closer together. You get this from two parallel surfaces being spaced apart, often in UV filter, and only when the light is (almost) monochromatic, like in the Aurora. The effect is related to socalled Fabry-Perot filtering. You can see an explanation here
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/fabry.html
and a picture of the rings here as well as more explanation here:
https://en.wikipedia.org/wiki/Fabry–Pérot_interferometer

PS: Take the UV filter off and try again :-)
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