Stop it! This makes my head hurt, and also makes me feel inadequate. I don't
need that! <g>
--Bob Whitmire
Registered Neanderthal
On Sep 23, 2013, at 8:18 PM, usher99@xxxxxxx wrote:
>>> I think I get it now (though I don't understand your
> equation/formula: 1/f
>>>> by (1+M)**2).
>
> To be more clear: Shutter speed to have 40-60% chance of sharp or
> slight blur =1/ ((focal length)*(1+M)**2)
> (multiple qualifications apply)
>
> One doesn't really have to measure blur, angular velocity for proof of
> principle just displacment of the image,
> IMO. How about take a 50mm and 100mm prime (macro lenses or zooms are
> more complicated as FL may change at close focus) and use extension
> only to get 1:2 mag or so--must be the same!!. The 100mm lens will have
> more working distance of course. Might be easiest to be sure the tripod
> head is level and just move at 5 deg (you pick) in left/rt plane and
> assess movement of the target image (target with rulers up down/left
> right would be great--must be available to download somewhere). At same
> mag, the target image would move much more with teh 100mm lens thus the
> same angular velocity of shake would result in more blur which turns
> out to be proportional ot the focal length.
> Perhaps a proper thought experiment is adequate. Rushing to get home
> and perhaps should think more about this b4 posting but wanted to
> respond. I haven't cleared this with Dr. Shake yet. Not sure why this
> isn't more obviously intuitatively correct. Increase mag will result
> in movement across more sensor pixels and thus more blur so perhaps
> that is obvious as well as increased angular velocity of shake leading
> to more blur.
> I am not an engineer or mathematician nor play one on TV though.
--
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