As mentioned there're always dependencies from the micro-lenses and probably also the AA-filter.
We are using the default camera settings for the vignetting tests - this is what we consider as normal user setting here. Technically you may debate the non-linear "curve" but 99.99% of the users don't shoot this way. Consequently this is reflected in our tests. You may, of course, criticize that we don't use the same S-curve across the board. Till we started with the D3x tests this wasn't really an issue because the S-curve was fairly similar across the board. However, again you are only talking about quantitative aspects, not qualitative ones - technically it is even possible to apply a mathematical transformation to normalize the data. We won't do so though. As long as the MTF data is not cross comparable it is just pointless to start with other aspects (honestly I'm aware of a method for the MTFs but it is simply way too much effort).
Feel free to check out the documentation over at imatest.com how it is all done. The testing procedure is no secret after all (apart from some adjustments of course).
We are using the default camera settings for the vignetting tests - this is what we consider as normal user setting here. Technically you may debate the non-linear "curve" but 99.99% of the users don't shoot this way. Consequently this is reflected in our tests. You may, of course, criticize that we don't use the same S-curve across the board. Till we started with the D3x tests this wasn't really an issue because the S-curve was fairly similar across the board. However, again you are only talking about quantitative aspects, not qualitative ones - technically it is even possible to apply a mathematical transformation to normalize the data. We won't do so though. As long as the MTF data is not cross comparable it is just pointless to start with other aspects (honestly I'm aware of a method for the MTFs but it is simply way too much effort).
Feel free to check out the documentation over at imatest.com how it is all done. The testing procedure is no secret after all (apart from some adjustments of course).