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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: Moose <olymoose@xxxxxxxxx>
Date: Sat, 14 Aug 2010 22:32:00 -0700
  On 8/14/2010 5:09 PM, Chuck Norcutt wrote:
> 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

Yes, decades ago, when I was a physics major at Berkeley, I did the math for 
diffraction across an edge. Not a chance 
now. :-)

>   (and also by contrast assumptions).

Sure, that assumption affects the calculations. BUT, where in film days there 
was little to be done after the fact, 
especially for edge contrast, where this is important, we now have tools to 
enhance both overall and edge contrast. I 
don't mind a modest loss of contrast.

Remember these images? 
<http://www.moosemystic.net/Gallery/MPhotos/Misc/8mileshigh/IMG_1473.htm>
- <http://www.moosemystic.net/Gallery/MPhotos/Misc/8mileshigh/IMG_1502.htm>
- <http://www.moosemystic.net/Gallery/MPhotos/Misc/8mileshigh/IMG_1507.htm>

Shoot through 8 miles of low atmosphere air suffused with shallow, late 
afternoon light, with a relatively low contrast 
mirror lens, and you get low contrast. 
<http://www.moosemystic.net/Gallery/tech/Process/Contrast_Etc/_MG_0419.htm>

Give me 16 bit depth and contrast is fungible. :-)

> 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.

All those calculations and tables are useful. Still, shooting a series of 
images at several apertures, as I have done, 
shows total system throughput differences.

> No table here covers the G11.  We'd have to do some (ugh) calculations.

The CambridgeInColor results aren't that different and the 1/1.8" sensor size 
in their calculator is close enough to the 
G11 1/1.7" sensor that I'm sure simple interpolation is quite accurate.

No Calculations Moose
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