I really have no idea if you're right or not. I'm traveling at the
moment but some time after I get home I plan to test this... not by
moving a pixel width (which I can't measure) but by displacing the
camera an easily measured distance. I'll observe the movement of the
image as produced by two lenses of different focal length set to
appropriate distances and extensions to create the same magnification
(or as close as I can get it). We'll see whether the setup with longer
focal length produces greater image motion even though at the same
magnification.
But your wording below gives me some pause to ask: What is the nature
of the motion being measured? Is it simple linear motion parallel to
the subject? Or is it angular motion about some (as yet) undefined
center point such as the "no parallax point"? If the latter then focus
will change unless the subject is a circular track with radius = the
object distance from the no parallax point. Not significant for a one
pixel motion but maybe significant for a 10mm image motion. Can I do
this with a simple X-Y slide or do I need a pano head? Just askin'.
But it will be more than a week before I can do this. Maybe you'll have
done it before I can get to it. I'll believe you... honest I will. :-)
Chuck Norcutt
On 9/20/2013 6:25 PM, usher99@xxxxxxx wrote:
> A bit more investigation shows that at pixel width "p", angular
> velocity of cam w, one pixel blur should occur at shutter speed of p/(f
> *w). No?
> Thus shutter speed required for a given blur is proportional to 1/f
> where f is the focal length. Magnification makes this more complex but f
> never drops out. Am getting to the 85% certain confidence level. This
> is either correct or not , there is no in between.
--
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