On 2010-12-25 20:30, Doug Franklin wrote:
On 2010-12-25 18:22, Igor Roshchin wrote:
I don't think that it is exactly the moire effect, as there
are no true interference, and there are no different-angle grids.
You are, of course, correct. I was using the term "moire" at more of a
meta level. The overlap is a sort of interference, if you look at it
from a high enough altitude. :-)
Think of it this way. With a moire, you're viewing the results of two
grids interacting with each other (we're gonna /way/ oversimplify here).
That interaction is more or less constant over time. Unless someone
goes through the screen door to get another beer or a tornado blows the
door off its hinges.
With the "spokes in the wheel" effect of the photo I posted, you're
seeing a single "grid" interact with itself, temporally, as it moves
through the duration of the exposure. That interaction is not constant
"at each and every instant in time" the way a moire is. In contrast to
a moire, it exists only at specific moments and for specific durations.
So I call them "temporal moires" (since I don't know what the real
term is).
That's what I meant by looking at it "from a high enough altitude".
--
Thanks,
DougF (KG4LMZ)
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