Yes, I didn't look at the details you referred but I did read some dpreview
lens test results, honestly say I don't see a clear picture how the lens
perform in real life. I don't like figures, I like to visual the test result
myself, most Canon lens results and some third party one are available in
the link I referred including the 70-200/2.8 IS, I like it much more than
the dp test because it is more straight forward and simple to me. You can
also compare the lenses test result side by side at different apertures.
I still think in real life a higher MP sensor can benifit to most lenses
even by some measures the lens resolve below the so call Nyquist frequency
of the sensor. Here is a 100% cropped 21/2 shot which shown the 5D Mark II
leave a lot to desire even with its 21MP sensor.
RAW converted with DPP with sharpness setting = 0.
http://www.accura.com.hk/temp/IMG_5622c.JPG
C.H.Ling
----- Original Message -----
From: "Chuck Norcutt"
> The lens resolution is not tested with the sensor. It's tested with
> DXO's measuring gear and the results are plotted against the Nyquist
> frequency of the sensor. It appears that you did not actually look at
> the test data I referenced or you would have seen that lens resolution
> did indeed exceed the sensor at some points. That would not have been
> possible to measure using the sensor.
>
> I can't talk about your results with the 70-200/4 since that's a
> different lens and I have no idea how well it performs or how any
> individual sample performs. The test I linked was for the 70-200/2.8 L
> IS. It did resolve more than the 5D but not as much as the 5D Mk II or
> 1Ds Mk III. But the Canon 50/1.4 and 85/1.8 primes do resolve to and
> beyond the resolution of these 21 MP cameras but not by much and not
> consistently across the frame. But different lenses (such as a hand
> picked OM 24/2) might do much better.
>
> Film is definitely the limiting factor on the Modern Photo tests. Most
> color films are in the 50-80 lpmm range with commonly used films around
> 50-60. Actual resolution between lens and film is termed the "system
> resolution" and can't exceed the smallest component. Norman Koren
> discusses this here as well as the "old" system math and the new MTF
> math <http://www.normankoren.com/Tutorials/MTF.html>
>
> Chuck Norcutt
>
>
> C.H.Ling wrote:
>> 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
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