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Re: [OM] Ugh! It's that pesky diffraction stuff...

Subject: Re: [OM] Ugh! It's that pesky diffraction stuff...
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sat, 22 Nov 2008 10:57:51 -0500
It's interesting to see that the DPReview test of the 70-200 is right in 
line with the Luminous-Landscape article indicating that f/11 is the 
optimum aperture for the 5D's sensor (assuming the lens can deliver). 
The 70-200 does hang in there until it gets over 135mm.

Chuck Norcutt

WayneS wrote:
> At 08:55 AM 11/21/2008, you wrote:
>> In a really long and very technical article from Luminous Landscape 
>> titled "Do Sensors “Outresolve” Lenses?" the cut-to-the-chase answer in 
>> in many cases is... yes.  The reason is the diffraction limits of lenses 
>> at various apertures.  You can read the entire, nerdy article here
>> <http://www.luminous-landscape.com/tutorials/resolution.shtml> or just 
>> skip to the conclusions which can be found in table 3 near the end.
> <snip>
> 
> Ah, an article right up my kind of ally. Do they mention the traditional
> hand-holding limit of 1/focal length needing modification?
> I'm still a 5mp shooter, even with my 12mp camera.
> 
> I've noticed on dpreview lens reviews they have an interactive chart
> of the lens resolution. Take for instance the Canyon 70-200/2.8 lens
> @70mm. Resolution peaks for a full frame sensor at F5.6-F8.
> (note, the aperture changes with left-right keys while zoom with
> up-down keys.)
> http://www.dpreview.com/lensreviews/canon_70-200_2p8_is_usm_c16/page5.asp
> 
> The dpreview chart has a line representing the Nyquist frequency, and
> sometimes the resolution exceeds that, indicating the lens out-resolves
> the test camera sensor, but for most apertures, the sensor out-resolves
> the lens.
> 
> I'm now glad the new camera spec to beat is no longer pixel count, but low
> noise, as witnessed by Nicon's latest cameras.
> 
> Didn't they replace the diffraction grating on the Hubble? Perhaps there are
> some diffraction tricks with apertures, like a fuzzy aperture. But then, I 
> guess
> that would not increase DOF. Back to combining shots with focus blend.
> 
> Wayne
> 
> 
> 
> 
> 
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