Different sites report different MTF-50 numbers for the same lens. For example, Digital Photography Review reports MTF-50 well below 1500 LW/PH at the center for the Nikkor AF-S DX 35mm f/1.8 G while Photozone reports 2027, both readings at F1.8.
The DPR sets the Nyquist Frequency (the theoretical limit of the sensor's resolution) of the D300 sensor (their test camera) at little below 1500. According to these numbers, this lens should be soft at the center at F1.8 on a D300 according to DPR, and out-resolve the sensor according to Photozone.
As a measure a physical phenomenon, shouldn't the MTF-50 test give consistent readings (excluding manufacturing variations between test lenses)?
If I see a review for lens A at site X and see a review for lens B at site Y, how can I compare the MTF-50 numbers of the two lenses and draw a conclusion which lens is more adequately sharp for my camera?