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Date: Mon, 29 Aug 2016 21:59:51 -0700
From: The Starmaker <starmaker@ix.netcom.com>
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Subject: Re: Viewing the spokes
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jimp@specsol.spam.sux.com wrote:
> 
> benj <benj@nobody.net> wrote:
> > On 8/29/2016 9:14 PM, jimp@specsol.spam.sux.com wrote:
> >> benj <benj@nobody.net> wrote:
> >>> On 8/29/2016 2:00 PM, jimp@specsol.spam.sux.com wrote:
> >>>> Sergio <invalid@invalid.com> wrote:
> >>>>> Viewing the spokes
> >>>>>
> >>>>> A wheel with spokes rolls on the ground. A stationary camera takes a
> >>>>> picture of the wheel. Due to the nonzero exposure time of the camera,
> >>>>> the spokes will generally appear blurred. At what location(s) in the
> >>>>> picture does (do) the spoke(s) not appear
> >>>>> blurred?
> >>>>
> >>>> Depends on the speed of the wheel, the expossure time and the pixel size.
> >>>>
> >>>> For sufficiently short exposure time and sufficiently slow wheel, nothing
> >>>> will appear blurred.
> >>>>
> >>>> For a long enough exposure time and a faster wheel, everything will be
> >>>> blurred.
> >>>>
> >>>> In general, if nothing in the image moves more than a a few pixels during
> >>>> the exposure time, the image will not appear to be blurred to the naked
> >>>> eye, but would be visible under magnification.
> >>>>
> >>>> If nothing in the image moves more than about a half pixel during the
> >>>> exposure time, nothing will be blurred.
> >>>
> >>> Usual chimp blather pretending to be 'smart" about science by throwing a
> >>> bunch of jargon around (nobody ever said the images were digital,
> >>> chimpo)
> >>
> >> It doesn't matter if the image is digital or on Kodachrome film.
> >>
> >> If the medium is film, you have to determine the pixel size from the
> >> grain size. For prints there is the grain size of the negative and
> >> then the grain size of the print paper and enlargement factor to concider.
> >>
> >> That one can do instantaneous calculations of position is irrelevant.
> >>
> >> The amount of blurring will be vastly different for an exposure time of
> >> 1/1000 of a second versus 10 seconds.
> >>
> >>
> >> <snip babble>
> >
> > Senile babble trying to change subject from fact that he missed the
> > entire point. Sure just babble on with irrelevant facts and maybe
> > someone will be snowed and not notice you totally buggered the question
> > and the head kook had to straighten you out.
> 
> If you mean your post where you said where the wheel touches the
> ground it is stationary, then your head is clearly up your ass.
> 
> It is stationary only instantaneously while the exposure time of any
> camera is NOT instantaneous.
> 
> If you posit an instantaneous exposure time, then nothing on the
> wheel is moving so there is never any blurring.
> 
> --
> Jim Pennino


the spokes atoms on the wheel is always moving...so there is always a blur...never say never.