Amorphous Wavy Lines Quiz
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Mysterious? -- Kyoto, Japan -- Copyright 2010 Jeffrey Friedl, http://regex.info/blog/
Nikon D700 + Sigma “Bigma” 50-500mm OS @ 500 mm — 1/125 sec handheld, f/6.3, ISO 6400 — map & image datanearby photos
Mysterious?

I gave my new Sigma “Bigma” 50-500mm superzoom a shot in the dark (so to speak) yesterday evening, and while looking through the results today, came across this throw-away shot of a spotlight at a rock garden. The photo is wholly unremarkable except for some very weird indistinct wavy parallel tracks that can be seen in the full-resolution version, as if snails had been sledding over the rocks.

But it's not sledding snails. Can you explain the wavy lines?

As always with my quizzes, I will not make submitted answers publicly visible for the first day or three, to give everyone a shot at answering without being influenced by others' answers.

(The high-resolution version was exported from Lightroom in its raw “as imported” state, without any post processing. Normally on a shot like this my post processing would consist of the 'x' key (delete), but on a shot like this that was worth saving, I'd normally add some luminance noise reduction, because the D700's low-light ability at ISO6400 is good, but not that good.)


All 15 comments so far, oldest first...

My guess would be that it has something to do with heat from the lamp, disturbing the air density and creating distortion of the light.
The lamp itself would perhaps be a halogen lamp. Its oscillations would be causing the repeating lines that would otherwise be just one line?
But I am a bit baffled by the fact that the lamp would have something like 35kHz, your shutter speed was 1/125 and I count seven lines, that leaves about 40 times less lines than should be there. Maybe a factor also of the sensor?

Or maybe something else entirely. 🙂

— comment by Bart Luyckx on April 19th, 2010 at 12:54am JST (7 years, 8 months ago) comment permalink

Heat waves maybe as the sensor reads the info coming through the lens. I seem to get these wavy lines from time to time here in Tucson , AZ while shooting my D40.

That’s the best I can tell, probably not correct but Its a shot in the dark ( no pun intended)

— comment by laurence zankowski on April 19th, 2010 at 1:48am JST (7 years, 8 months ago) comment permalink

I think they might be signs of heat waves radiating from the spotlight.

— comment by Steve Crane on April 19th, 2010 at 2:23am JST (7 years, 8 months ago) comment permalink

I’m guessing everyone will go with heat waves from the light. I’m going with grass/vegetation that’s very close to you and out of focus… Although it looks like heat waves from the light! 😉

— comment by JasonP on April 19th, 2010 at 2:32am JST (7 years, 8 months ago) comment permalink

I guess it’s a word/sentence “written” on the rocks?

(Nice lens review btw, would you recommend it for someone looking for a supplementary lens above Nikkor 70-200 2.8?)
Regards from Belgium!

— comment by aCCuReRaS on April 19th, 2010 at 2:37am JST (7 years, 8 months ago) comment permalink

You are looking at two masses of air that differ in refractive index as the air around the spotlight is warmer than the air further away from the spotlight. Refractive index gradients are formed in the air and they cause bending of the light rays in the direction of increasing refractive index. This effect create alternating light and dark waves. This is similar to Schlieren photography that uses a knife edge to block some of the light rays and separate a fluid or a gas by a refractive gradient and this allows the observation of varied flow dynamics.
Fernando

— comment by Fernando on April 19th, 2010 at 7:17am JST (7 years, 8 months ago) comment permalink

Fingerprint on the lens?

— comment by Marcina, USA on April 19th, 2010 at 8:58am JST (7 years, 8 months ago) comment permalink

Mirage! … Does this sound funny ;-)?

— comment by Britto on April 19th, 2010 at 10:12am JST (7 years, 8 months ago) comment permalink

Diffraction

— comment by Paul Morris on April 19th, 2010 at 1:31pm JST (7 years, 8 months ago) comment permalink

My guess is that its schlieren, right? Same thing as when you look at the hot air over a barbeque grill, hot car, or hot road. “I could see the heat coming off the road…” -that kinda’ thing.

— comment by Ron Evans on April 19th, 2010 at 11:15pm JST (7 years, 8 months ago) comment permalink

It may be the dispersion of light caused by the sets of angled ribs on the glass refractor of the light source.

— comment by Marcel on April 20th, 2010 at 10:19am JST (7 years, 8 months ago) comment permalink

Out of focus cables???

— comment by Gianluca on April 21st, 2010 at 2:32pm JST (7 years, 8 months ago) comment permalink

I would think it’s an out of focus object, probably some blades of grass.

— comment by Daniel Cutter on April 22nd, 2010 at 12:03am JST (7 years, 8 months ago) comment permalink

I’ve posted the answer here. —Jeffrey

— comment by Jeffrey Friedl on April 25th, 2010 at 12:30pm JST (7 years, 8 months ago) comment permalink

It’s the effect of the optical image stabilizer (or vibration reduction for Nikon)

— comment by J on April 25th, 2010 at 6:12pm JST (7 years, 8 months ago) comment permalink
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