Zeiss Milvus 2/100M
D500 @ x 0.27
This lens has an superb all round performance at this magnification on a D500, probably reaching what is achievable on the 21 MP D500 sensor.
Resolution: This lens shows excellent results from fully open to f/8
Chromatic aberration: very low right from fully open at f/2
Vignetting: Moderate from f/2.8 stopped down
Macro Sweet Spot: f/8