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Re: [OM] DOF and diffraction redux - again [was Focus Accuracy Test - Oh

Subject: Re: [OM] DOF and diffraction redux - again [was Focus Accuracy Test - Oh what misery we bring upon ourselves]
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sat, 14 Aug 2010 20:09:07 -0400
I use the Luminous-Landscape numbers as found in table 3 here:
<http://www.luminous-landscape.com/tutorials/resolution.shtml>
As you can see, the diffraction limit varies by wavelength (and also by
contrast assumptions).  I've chosen the middle column which represents
yellow-green light at 550nm.  It actually claims 16 MP at f/11 so maybe 
the 5D at 12.7 MP is good to about f/12.  But 7 MP at f/16 is too much 
loss for me.  Preserve the yellow-green range for the landscapes and let 
the blue sky come along.  No table here covers the G11.  We'd have to do 
some (ugh) calculations.

Chuck Norcutt


Moose wrote:
> Hey Chuck, some more thoughts on empirical results vs. calculations.
> 
> You have for some time contended the 5D is diffraction limited at
> f11. I don't know the source of your calculations. The "Diffraction
> Limited Aperture Estimator" on the link somebody posted a bit ago,
> says it is f16, which agrees with my experience.
> <http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm>
> 
> 
> Obviously, there are calculations, and then there are calculations.
> 
> On the same page, the "Depth of Field Equivalents" calculator says*
> the equivalent aperture for the G11 is f4. I feel it's closer to
> f5.6, but haven't done any controlled testing. it may, however, be an
> example of something like this, "Even though diffraction softening
> affects all systems equally at the same DOF, the system that began
> with more detail will retain more detail " from:
> <http://www.josephjamesphotography.com/equivalence/index.htm> ,where
> the lower level of pixel level detail means diffraction effects
> aren't visible until stopped down further.
> 
> Optimum Aperture Moose
> 
> *Interpolated, as they don't have the exact sensor size as a choice.
> 
> 
-- 
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