02-26-2015, 09:22 PM
Quote:How in the world does the Canon beat it? The resolution is clearly much better with the Sony lens.A sensor with 55% more pixels inflates the numbers for sony's sensor.
The format for imatest results is lw/ph, if the lens and detector were perfect you would see a 1:1 correlation between lw/ph and the longest edge of the sensor in px.
The 5D2 has 5600px long edge. Peak imatest numbers for it are about 3850lw/ph but this is an exceptionally good lens performance (24L II at f/4) and the "true max" is about 3700. Calculate the sensor's "resolution factor" here = 66% which is very expected.
A7r -> 7600px long edge. Peak resolution is about 4700lw/ph or 61% which is a bit below expectation.
We may bump canon's numbers by the % difference between the two in linear resolution = 7600/5600 = 35%.
We may also add 10-15% on top of that for the removal of the AA filter but some may disagree with this so I will do it separately.
16mm comparison:
Center:
16-35/4L : 4800lw/ph
16-35/4S : 4500lw/ph
Corner:
16-35/4L : 3500lw/ph
16-35/4S : 3199lw/ph
AA-filter compensated:
Center:
16-35/4L : 5280lw/ph
16-35/4S : 3850lw/ph
Corner:
16-35/4L : 3500lw/ph
16-35/4S : 3199lw/ph
Comparisons are pretty similar at other focal lengths.
Canon also achieves this resolution with 50% less vignetting. Not to mention the (astronomically) worse constraints because efl << bfl for the canon design.
CAs on the canon are also about 1/2px or about (36/5600) = 1/2 * 6.4um = about 3.2um across the range.
Sony has about (36/7600) = 4.7um pixels * 1-2px of lateral CA = at least 4-8um of CA.