Well, Larry, picking up on my hint about the physics content
was very close to the full correct answer.
These are water "particles", aka droplets. Except that they are
specially shaped. The photo was taken at a splash pad.
The splash pad has many different water jets. I didn't pay attention, but
after looking at the photos, I suspect some of those jets work in the
pulse mode that produces in this short "streaks".
Here is a larger portion of the photo that gives an idea of how this
looks, and you can see the "regular" water droplets:
http://42graphy.org/misc/puzzle-2015-06-29/_IR26728.jpg
As for the physics part, - Larry guessed a large portion.
Here is what I thought when I was posting the photo:
Depending on the direction (and the initial speed/height), these streaks
have different velocities, and therefore appear of a different length.
However, looking at the photo again, and seeing how the round droplets
are shaped, I don't exclude a possibility that different jets produce
different pulse lengths.
The photo was taken with 60-250/4 at 140mm and 1/500s
from the distance of about 40-50 feet (some 15 m).
Here is yet another photo taken under similar conditions (98mm):
http://42graphy.org/misc/puzzle-2015-06-29/_IR26789.jpg
And with all pixels (warning if you are on cell connectivity: large file:
2MB ):
http://42graphy.org/misc/puzzle-2015-06-29/_IR26789-2.jpg
Here is the prize for all who looked and tried to solve this puzzle:
A fun shot with similar type of water "particles":
http://42graphy.org/misc/puzzle-2015-06-29/_IR26801.jpg
Igor
Larry Colen Tue, 30 Jun 2015 00:41:46 -0700 wrote:
Igor PDML-StR wrote:
The idea for this puzzle came while I was working on some recent
photos...
I think this puzzle is rather simple. (And there is some interesting
physics in it.)
What is this:
http://42graphy.org/misc/puzzle-2015-06-29/_IR26728-3.jpg ?
It's a time exposure of some sort of moving particles. I don't know
whether the length of the path has to do with difference in speed, or
direction. I.e. traveling normal to the axis of the lens would be a longer
path than along the axis.
I would guess that the particles are lit, but shot against a black
background.
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