I don't understand how dpreview test the lens' "Nyquist frequency" with a
low res 5D. But any day I will take a higher resolution camera if I can
justify for the cost, storage memory and processor power, I think I need
40MP at least.
Have a look on this test site with 70-200/4 IS, even at F11 I see the result
of 1Ds Mark III better than 1Ds Mark II not to mention the 5D.
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?FLI=0&API=0&Lens=404&FLIComp=0&APIComp=3&LensComp=118&CameraComp=9&SampleComp=0&Camera=453
I remember people mentioned the 'aerial resolution' (?) of lenses can over
200lp/mm. And the guy in a Tamron lens site mentioned he seen 100 lines per
mm (I'm pretty sure he mean line pair) with a Tamron 24-48 while Modern
Photography only seen 50 lines per mm with film, he believe the different is
limitation of film.
http://www.adaptall-2.com/articles/Resolution_and_Contrast.html
I'm with Ken, I believe we need much higher resolution sensor to resolve the
details then 2 pixels per line pair consider the details may not be
perfectly aligned with sensor. I have a strong feeling that my 24/2 can do
better with higher than 21MP sensor.
C.H.Ling
----- Original Message -----
From: "Chuck Norcutt"
> What got me on this point to begin with was DPreview's test of the Canon
> 70-200/2.8L which is one of the more revered zooms in Canon's stable.
> Check this page which is the test of that lens on a 5D body.
> <http://www.lenstip.com/115.1-article-Polarizing_filters_test.html>
> Use the aperture slider and watch the resolution graph change. Only at
> f/5.6 to f/11 is the 70-200 able to equal or slightly exceed the 12.7
> megapixels of the 5D sensor (represented by the line labeled "Nyquist
> frequency"). Below f/5.6 some irregular things start happening and
> above f/11 diffraction begins its steady toll against resolution. So,
> if this lens can just barely handle a 5D it certainly can't handle the
> pixel density of a 50D (15 MP on an APS-C size sensor). At f/5.6 to f/8
> the 5D Mk II will pull a bit more out of the lens than the 5D but not a
> great deal. To utilize the resolving power of the 5D Mk II you need
> very good primes. Here you can see that the 50/1.4 can resolve to the
> level of the 1Ds Mk III (21 MP, like the 5D Mk II) at f/5.6 to f/8 (but
> not elsewhere).
>
> Quite apart from noise, one reason to want a camera with larger pixels
> is to be able to find a lens that can resolve to the level of the
> sensor. Little pixels just make the job harder on the lens. That said,
> it's also easier to make a lens that resolves little pixels if the
> sensor is small and the lens doesn't have to cover a large area.
>
> Chuck Norcutt
>
--
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