There is a much simpler way to beat the "normal" diffraction limits when doing b/w: shooting with ortho- or unsensitized film or using colour filters in the direction of the blue part of the visible spectrum.
How can this work? With normal film you have for instance at f22 a diffraction limit of about 70 lines per millimeter (for shooting infinity) for panchromatic-film whose spectral-sensitivity-curve is centered at about 500 nm. When shooting ortho- or even unsensitized material, the center of the spectral-sensitivity-curve is shifted more and more in the blue direction of the spectrum. At corresponding wavelengths for instance at 486 nm you have already an increased diffraction limited resolution of 75 lpm (f22, infinity) and at 436 nm a (17 % higher than at 500 nm) value of 82 lpm (f22, infinity). I think you see where I want to go....
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