With 10 Elements in 6 groups, the HR series of lenses are nearly diffraction limited all the way up to F/4. Use from F4 - F5.6 for the sharpest results with your 39-80 MP digital backs. The lens series has been renamed Digaron-S is still sold as the sharpest option Rodenstock/Linos has to offer.
Use with focus stacking for the sharpest possible results with a deeper depth of field.
Good for backs with sensors that are 5 microns or larger.