Mardi 4" achromat, ETX-70, 8"cat. Whitepeak Lunar Observatory Website
1 What i gather from these charts, as applied to the spectral situation of 52 Ori (if located at ~500nm as assumed), is that this pair lies smack in the middle of the maximum sensitivity of the rods, making for a maximally saturated point source image-- as formed by the least acute receptors of the eye, the rods.
2 This could increase the diameter of the Airy disk, no asnd could also explain the need for silly high magnifications as such large spearations are neeeded for such reduced acuity as when so dependant upon the rods for reolution?
3 And also I notice a simultanious response by the color receptors of the eye in a region of reduced combined sensitivity (vertical line drawn at 500nm shows this quite clearly in all diagrams).
4 This would seem to indicate a minimalized involvement of the most acute sensors re; acuity, the cones and fovea centralis generally, in resolution of the image.
5 So, in sum, with a color pair such as 52 ori, we'd have a highly saturated (effectively enlarged due to use of low acuity receptors) pair of disks scopticly and a quite low saturation of the lesser diameter 'blue' Airy disk photopically, the result being....
6 ....that as far as our eyes are concerned, a blue pair (>500nm) could be one of the most challenging color pairs to split, dispite what diffraction theory says about reduction in the size of a "blue" Airy disk.
7 As to the increased size of the Airy disk as viewed by the rods, this comes as a (assumed) result of increased saturation at this wavelength (500) which i assume could cause something akin to 'blooming' of the Airy disk?