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Re: [OM] Speaking of lenses [was Speaking of sharpness ...revisit to SS

Subject: Re: [OM] Speaking of lenses [was Speaking of sharpness ...revisit to SS for handheld macro
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 18 Sep 2013 05:55:22 -0400
I think I'll need to think about this for a very long time.  On the 
other hand, I probably won't.  I think you should be measuring the 
motion of the sensor relative to the exit pupil rather than relative to 
the object.  If relative to the exit pupil focal length will disappear 
from the calculation and leave only magnification.

Chuck Norcutt


On 9/16/2013 7:26 PM, usher99@xxxxxxx wrote:
> JW writes:
>>> In a practical sense, it doesn't really matter to me which macro is at
>>> hand, but I know that I will handhold a 50 better than a 90 or
> certainly
>>> than the 135.  But if I have a tripod at hand, bring on the long ones.
>>> (Make certain to bring the QR plates, eh Ken? Beat you to it!)
>
> Seems we have a bit of a schism as to whether FL makes a difference
> (independent of mag) in shutter speed required to handholdfor macro
> with Moose and Chuck on one  side and JW and me on another.  I had
> previously thought that Magnification was the true only factor until
> investigated the geometry a tad.
>
> See derivation that FL does indeed matter---
>
> http://lists.tako.de/Olympus-OM/2013-09/msg00278.html
>
> I have seen a post by FMer self descirbed as a "recovering physicist"
> that the underyling assumptions
> that lower magnification is just a restricted subset of the macro
> estimation is basically correct though the exponent may be a tad off
> depending on the usual centers of rotation occuring in typical camera
> shake.
>
> Current working estimate then is SS required for about 50% sharp is
> 1/FL *  (1+M)**2.
> Rebuttals?
>
> Steady as she goes, Mike
>
>
-- 
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