11-02-2010, 09:45 AM
[quote name='PuxaVida' timestamp='1288684930' post='3904']
The cornerstone of their statement, which compares the size of the airy disk (diffraction pattern) with pixel size of the sensor came logical to me. Because if the pixel size is smaller than the airy disk, then the diffused photons will be collected by the neighbour pixel, which might alter the real image because of the color recognition concept of the bayer filter. Can this be a problem also for the film?
[/quote]
The best test for all these theories is simply to carry out controlled testing on two cameras and see what you get. There were all kinds of theories on diffraction that got me worried when I bought the 7D. So, I mount the same lens (17-55 f/2.8 IS) on my 12 MP 450D and 18 MP 7D. Made use of tripod, manual focus under live view, cable release, identical exposure etc etc etc. And the result? I can pixelpeep for all I want, but there is no significant difference in terms of diffraction effects from f/2.8 to f/11 between the 450D and 7D. 7D images do not appear any worse than those from 450D at f/11.
My conclusion? To hell with all those armchair theorists and their flawed postulates! The end result, i.e., the images, is what counts.
On a slightly different but related note, [url="http://www.juzaphoto.com/eng/articles/canon_7d_review.htm"]Juza[/url] has direct comparisons between the APS-C 7D and FF 1Ds3. This is what he says:
"When the 7D has been announced, I was doubtful about its image quality at high ISO... Surprisingly, the 7D is relatively good in this aspect. It is not as good as the 1DsIII, but the difference is small - I'd say about 0.5 stop - and it is a bit better than the 500D and 50D.... In this test, I have compared 1DsIII, 7D and 500D from ISO 100 to 12800. The images are 100% crops from the unprocessed RAW file...
The dynamic range is about the same. The 7D seems to capture slightly more detail into highlights (even though it shows a slight magenta cast), while the 1DsIII captures a bit more detail in the shadows - but the differences are so small that in practice you won't see any real difference."
And he backs up his statements with pictures from controlled tests. No armchair theories here.
IMHO, FF offers three advantages over APS-C: shallow depth of field, less demanding on lenses and slightly (not even one stop) better high ISO performance. Dynamic range is NOT one of them. That has been the case since the 5D days and it has not changed.
The cornerstone of their statement, which compares the size of the airy disk (diffraction pattern) with pixel size of the sensor came logical to me. Because if the pixel size is smaller than the airy disk, then the diffused photons will be collected by the neighbour pixel, which might alter the real image because of the color recognition concept of the bayer filter. Can this be a problem also for the film?
[/quote]
The best test for all these theories is simply to carry out controlled testing on two cameras and see what you get. There were all kinds of theories on diffraction that got me worried when I bought the 7D. So, I mount the same lens (17-55 f/2.8 IS) on my 12 MP 450D and 18 MP 7D. Made use of tripod, manual focus under live view, cable release, identical exposure etc etc etc. And the result? I can pixelpeep for all I want, but there is no significant difference in terms of diffraction effects from f/2.8 to f/11 between the 450D and 7D. 7D images do not appear any worse than those from 450D at f/11.
My conclusion? To hell with all those armchair theorists and their flawed postulates! The end result, i.e., the images, is what counts.
On a slightly different but related note, [url="http://www.juzaphoto.com/eng/articles/canon_7d_review.htm"]Juza[/url] has direct comparisons between the APS-C 7D and FF 1Ds3. This is what he says:
"When the 7D has been announced, I was doubtful about its image quality at high ISO... Surprisingly, the 7D is relatively good in this aspect. It is not as good as the 1DsIII, but the difference is small - I'd say about 0.5 stop - and it is a bit better than the 500D and 50D.... In this test, I have compared 1DsIII, 7D and 500D from ISO 100 to 12800. The images are 100% crops from the unprocessed RAW file...
The dynamic range is about the same. The 7D seems to capture slightly more detail into highlights (even though it shows a slight magenta cast), while the 1DsIII captures a bit more detail in the shadows - but the differences are so small that in practice you won't see any real difference."
And he backs up his statements with pictures from controlled tests. No armchair theories here.
IMHO, FF offers three advantages over APS-C: shallow depth of field, less demanding on lenses and slightly (not even one stop) better high ISO performance. Dynamic range is NOT one of them. That has been the case since the 5D days and it has not changed.