09-25-2011, 09:51 PM
[quote name='wim' timestamp='1316985309' post='11850']
However, as indicated, somehow Imatest seems to coax more resolution from the lens/sensor combination than seems possible theoretically.[/quote]
Using any sampling rate, you can retrieve data from almost any frequency, even those above the Nyquist. For unknown broad spectrum signals, this is a problem of course that aliasing can occur and you can't determine where the apparent signal spectrum is from. However, in the case of the Imatest test, the signal is effectively known and I assume they use that to separate the signals of interest above or below the Nyquist. I further assume this is limited in scope as reducing signal-to-noise would render it unusable if you try to take this too far.
However, as indicated, somehow Imatest seems to coax more resolution from the lens/sensor combination than seems possible theoretically.[/quote]
Using any sampling rate, you can retrieve data from almost any frequency, even those above the Nyquist. For unknown broad spectrum signals, this is a problem of course that aliasing can occur and you can't determine where the apparent signal spectrum is from. However, in the case of the Imatest test, the signal is effectively known and I assume they use that to separate the signals of interest above or below the Nyquist. I further assume this is limited in scope as reducing signal-to-noise would render it unusable if you try to take this too far.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.