The maximum aperture of this lens in macro use decreases to f/5.6 at maximum magnification but the performance stopped down is excellent with low chromatic aberration compared with other lens designs. The peak resolution of this lens at x1 magnification on a D800 is similar to that of the Laowa 100mm reviewed on this site but the Nikon 60mm f/2.8D lens achieves this at f/11 compared with f/5.6 on the Laowa 100mm. which is more useful for macro photography. The performance of this lens is also extremely good on a D500 at x0.27 and x0.5.
Distortion: This lens exhibits moderate of between 0.08% to 0.15% pin-cushion on a D500 and 0.29% to 0.34% pin-cushion on a D800.
At f/8 this lens is corner to corner sharp!