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.
Without knowing the tire size at all you could use the un-overlapped part of
the tire's white manufacturers name at the top of the tire to roughly calculate
the amount of rotation in 1/250 of a sec. as a percent of full rotation. The
lighter ends of the ghost image seems equal fore and aft.
I think Paul gave the right explanation, or at least that the
explanation I head the moment I read the answer.
My estimates gave similar numbers, but I didn't have time to write
a message, so I was sure somebody else would write it.
(That's what professors often do when teach a class: they let
On 2010-12-25 11:59, Igor Roshchin wrote:
I think Paul gave the right explanation, or at least that the
explanation I head the moment I read the answer.
Yep, the more I've thought about it the more I think Paul was right, too.
I should note that a similar effect can be expected when the
I couldn't be bothered to do any research at all and just used 600mm as the
tire height. (Are your students this lazy Igor?)
Race slicks are normally sold as being overall width by overall height by rim
size. I'm used to seeing it expressed in mm x mm x inch, but the figures there
are about
Sat Dec 25 11:26:39 CST 2010
Doug Franklin wrote:
I should note that a similar effect can be expected when the tire
makes
not about 1/15th of a turn, but also 2/15th, 3/15th, etc. (N/15),
but the contrast will be lower, and it probably wouldn't work beyond
N=3 (or maybe even 2,
Yep agreed, this is not a Moire effect, simply overlapped arcs of blurred
spoke.
- Peter
-Original Message-
From: Igor Roshchin
Sent: Sunday, December 26, 2010 9:52 AM
To: PDML@pdml.net
Subject: Re: The Physics of Photographing Moving Subjects
Sat Dec 25 11:26:39 CST 2010
Doug
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
On 2010-12-24 1:37, Larry Colen wrote:
Doug, there should be a every body can see this URL at the bottom of the
page, but you're the only one that'll see it.
Thanks for the tip Larry. I already had the security set to everyone
but posted the wrong link. Here's the one that Facebook claims
On 2010-12-23 23:38, Paul Ewins wrote:
[...] During the 1/250 sec each spoke travel a little
bit further than the distance to the next spoke. This means
there are sections where it has doubled up (i.e. both the
current and previous spoke have occupied that position during
the exposure) so you
On 2010-12-23 23:49, paul stenquist wrote:
Too small an image to see what you're referring to -- at least for my old yes.
Let's see a wheel at 100%.
Here's the 100% view of just that rear wheel:
http://nutdriver.org/IMGP2777-wheel-detail.jpg
--
Thanks,
DougF (KG4LMZ)
--
PDML Pentax-Discuss
You can see some of that effect in these iPhone pictures.
http://blog.flickr.net/en/2010/08/24/rolling-rolling-rolling-shutter/
On Fri, Dec 24, 2010 at 8:49 AM, Doug Franklin
jehosep...@mindspring.com wrote:
On 2010-12-23 23:38, Paul Ewins wrote:
[...] During the 1/250 sec each spoke travel
OK, I know there are some folks around the list that know a lot more
about the physics, optics, and other science surrounding our hobby than
I do. And I'm asking their help in understanding something.
In the following photo, take a specific look at the way that the wheels
and in particular
Subject: The Physics of Photographing Moving Subjects
OK, I know there are some folks around the list that know a lot more
about the physics, optics, and other science surrounding our hobby than
I do. And I'm asking their help in understanding something.
In the following photo, take a specific look
To: Pentax-Discuss Mail List
Subject: The Physics of Photographing Moving Subjects
OK, I know there are some folks around the list that know a lot more about
the physics, optics, and other science surrounding our hobby than I do. And
I'm asking their help in understanding something.
In the following
I'm not sure that I'm answering your question correctly, but I threw a whole
lot of assumptions at a spreadsheet and came up with the conclusion that in
that 1/250 sec the wheel rotated around 1/10 of a revolution. If I am counting
right there are 15 spokes in the wheels. During the 1/250 sec
Too small an image to see what you're referring to -- at least for my old yes.
Let's see a wheel at 100%.
Paul
On Dec 23, 2010, at 10:39 PM, Doug Franklin wrote:
OK, I know there are some folks around the list that know a lot more about
the physics, optics, and other science surrounding our
On Dec 23, 2010, at 11:49 PM, paul stenquist wrote:
Too small an image to see what you're referring to -- at least for my old
yes. Let's see a wheel at 100%.
That would be for my ole eyes.
Paul
On Dec 23, 2010, at 10:39 PM, Doug Franklin wrote:
OK, I know there are some folks around
On Dec 23, 2010, at 8:37 PM, John Coyle wrote:
Wants me to log in.
Not a Facebook user, so no can do.
Doug, there should be a every body can see this URL at the bottom of the
page, but you're the only one that'll see it.
--
Larry Colen l...@red4est.com sent from i4est
--
PDML
On Dec 23, 2010, at 8:38 PM, Paul Ewins wrote:
I'm not sure that I'm answering your question correctly, but I threw a whole
lot of assumptions at a spreadsheet and came up with the conclusion that in
that 1/250 sec the wheel rotated around 1/10 of a revolution. If I am
counting right
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