Today's (Wed 4th May) issue of British Journal of Photography carries a test of 4 Nikon zooms on a D2X by Anders Uschold using the DCTau lens test methodology. The explanation of this methodology in BJP is gibberish probably due to poor translation from the original German (I suspect these test have or will appear in a German magazine). Can anyone explain, in words that a retired aerospace engineer who managed research programmes in control system engineering can understand, exactly what the parameters coefficient of resolution and net file size are?