MTF at the center of the field is naturally high, at the edge of field will drop off a lot that is the difficulty.
For this lens with diffraction limited performance, the MTF should be 0.99 at 10lines/mm, 0.98 at 20line/mm and 0.95at 40line/mm all over the field
This lens has MTF 0.69 at the center and 0.49 at the edge for 20L/mm
This lens has MTF 0.42 at the center and 0.19 at the edge for 40L/mm
It's a very good lcommerical ens.
