andybarton Posted March 12, 2016 Share #1 Posted March 12, 2016 Advertisement (gone after registration) Here is a shot I took last week in Tromso, Norway. I was lucky, as the aurora isn't often this bright over the city Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! However, in the dead centre of the sensor, there is a concentric ring pattern, that I have never seen before. Any ideas? Thanks Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! However, in the dead centre of the sensor, there is a concentric ring pattern, that I have never seen before. Any ideas? Thanks ' data-webShareUrl='https://www.l-camera-forum.com/topic/257930-strange-artefact-in-centre-of-image-m240/?do=findComment&comment=3006489'>More sharing options...
Advertisement Posted March 12, 2016 Posted March 12, 2016 Hi andybarton, Take a look here Strange artefact in centre of image (M240). I'm sure you'll find what you were looking for!
andybarton Posted March 12, 2016 Author Share #2 Posted March 12, 2016 Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/257930-strange-artefact-in-centre-of-image-m240/?do=findComment&comment=3006490'>More sharing options...
pico Posted March 12, 2016 Share #3 Posted March 12, 2016 Uh oh, Andy. You have exposed the HAARP project phenomenon. . Link to post Share on other sites More sharing options...
pop Posted March 12, 2016 Share #4 Posted March 12, 2016 Aren't you the lucky one. I don't really understand the phenomenon, but that thing looks like an Airy disk, i.e. a diffraction pattern or interference pattern. I think it has somehow to do with the aurora being monochromatic, that is light of exactly one wavelength only. Did it occur in more than one picture, and at which aperture did you take it? A small one? Why? Some more searching yields this explanation: it could be a sort of halo, caused by ice cristals in the air: https://en.wikipedia.org/wiki/Corona_(optical_phenomenon) Link to post Share on other sites More sharing options...
masjah Posted March 12, 2016 Share #5 Posted March 12, 2016 This is fascinating, and certainly looks like a diffraction pattern, which begs the question, where is the diffraction taking place? What aperture were you using Andy, and what lens? I'd be tempted to experiment taking a few photographs of an illuminated (not too powerful) LED (NOT a Laser source!) such as a stand-by indicator light on a television in a darkened room to see if anything similar could be reproduced. I wonder if the diffraction could be taking place at an interface between two lens elements? Link to post Share on other sites More sharing options...
JPH1962 Posted March 12, 2016 Share #6 Posted March 12, 2016 If this is from DNG and you processed in Lightroom... try again switching off the lens profile. I had once something similar with Monochrome and Lux 35 FLE.. Good luck JPH Link to post Share on other sites More sharing options...
Exodies Posted March 12, 2016 Share #7 Posted March 12, 2016 Advertisement (gone after registration) Was a filter involved? Link to post Share on other sites More sharing options...
andybarton Posted March 12, 2016 Author Share #8 Posted March 12, 2016 Thanks guys This was probably with the 35 ASPH - it is my only coded lens, and I am lazy about changing lens profiles, so I can't be sure. Regardless, there is a Leica UV filter on all my lenses. I will check the lens profile thing in Lightroom, and have a look at the in camera jpg to. Link to post Share on other sites More sharing options...
andybarton Posted March 12, 2016 Author Share #9 Posted March 12, 2016 Lens profile makes no difference. The shot would have been wide open Link to post Share on other sites More sharing options...
CheshireCat Posted March 12, 2016 Share #10 Posted March 12, 2016 https://en.wikipedia.org/wiki/Newton%27s_rings Link to post Share on other sites More sharing options...
jaapv Posted March 12, 2016 Share #11 Posted March 12, 2016 I think it is condensation between the filter stack on the sensor. Remember slides between glass? Link to post Share on other sites More sharing options...
jmahto Posted March 12, 2016 Share #12 Posted March 12, 2016 Here is a shot I took last week in Tromso, Norway. I was lucky, as the aurora isn't often this bright over the city Aurora-over-Tromso.jpg However, in the dead centre of the sensor, there is a concentric ring pattern, that I have never seen before. Any ideas? Thanks First, love the picture... Great shot. Now to the pattern. I don't claim to know the answer but did some googling around and found this. http://photo.net/bboard/q-and-a-fetch-msg?msg_id=001kuJ Link to the picture in discussion (it is copyrighted). http://static.photo.net/attachments/bboard/001/001kuJ-6406484.jpg The pattern was visible in slide film and print film both from multiple cameras, lens and multiple users. Therefore digital sensor/specific lens is ruled out. Based on the discussion in the above link, it has something to do with your filter....Quoting from the discussion... "With my Nikon lenses I have found that long exposures result in concentric circles showing up in the center of the images when I use a filter of any kind. Nikon says this is due to the high reflectivity of the aurora. Thanks to the University of Alaska forecaster, Chuck Deehr, the explanation follows. "These are interference fringes due to the parallel faces of the filter and to the narrow spectral emission at 5577 Angstroms in the aurora. That green, atomic oxygen emission line is the strongest emission in the aurora near our film and eye peak sensitivity, so it shows up first when there is any device in the optical path which sorts out the spectral emissions." So, don't use filters!" Therefore it is something to do with filter and light spectrum of aurora. Link to post Share on other sites More sharing options...
Ernstk Posted March 12, 2016 Share #13 Posted March 12, 2016 Concentric circles notwithstanding, it's a fabulous photo. Link to post Share on other sites More sharing options...
hepcat Posted March 12, 2016 Share #14 Posted March 12, 2016 I don't care about the concentric circles... that is one absolutely stunning photograph! Wow! Link to post Share on other sites More sharing options...
Peter H Posted March 12, 2016 Share #15 Posted March 12, 2016 Nice one Andy! Link to post Share on other sites More sharing options...
enboe Posted March 13, 2016 Share #16 Posted March 13, 2016 My hypothesis - Newton's rings. I remember these from an old text on grinding your own telescope mirrors. Link to post Share on other sites More sharing options...
cbretteville Posted March 13, 2016 Share #17 Posted March 13, 2016 It does remind me of slides mounted in GePe frames w/glass projected on a screen. I wonder what causes them, sensor cover glass? Cheers, Carl Link to post Share on other sites More sharing options...
ECohen Posted March 14, 2016 Share #18 Posted March 14, 2016 fabulous photo....and if the circles bother you its an easy retouch Link to post Share on other sites More sharing options...
jdlaing Posted March 14, 2016 Share #19 Posted March 14, 2016 I think it's the UV filter. Link to post Share on other sites More sharing options...
BVillanueva Posted March 14, 2016 Share #20 Posted March 14, 2016 How did you save the file?, On ACR if you save it using max 12 it'll disappear, if you you use a medium or small you get artifacts, esp if you apply a bit more contrast. Although I could be wrong, might be a diffraction. Link to post Share on other sites More sharing options...
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