If you wish to get better sharpnes at high magnification ratios here are three lenses designed for that work.
50mm Rodagon G
40mm 5.6 Zeiss S-Biogon
60mm F 4 Zeiss S-Orthoplanar.
The two Zeiss lenses are exceptionally good and are designed for magnification ratios of 10-70x. They are very hard to find. The 40mm S-Biogon has no aperture. It comes with a graduated ND filter for exceptional smoothness On Ebay thes have been going, when available for about $500.00
The 60MM S-Orthoplanar is exceptionally hard to find, The only one that I have seen sold on Ebay sold for $2000.00 2 years ago.
Zeiss states on their website in Camera and Lens news that with 10-70x magnifications these lenses will far out preform anything on the world's market.
Theses 2 lenses were originally offered for reprographic work. I understand
that they originally sold for circa $20,000.00 each.
The Rodagon G is designed for a 20x magnification factor.