The (hopefully!?) useful info above was (slowly) assembled over the years in large part thanks to the following folks: Jacopo "Scensiato" Antichi for his advice on the Airy Disk figures, reminding me about the "holy" Born & Wolf and giving me a privileged perspective on the daily life of a designer of future astronomical instruments and his dreamy world; Lucia "Stordita" Marchetti for the many questions we asked ourselves about AB and Vega magnitudes while she was in the no less fancy limbo of her Thesis writing; Gabriele "Subcomandante" Mainetti for our lengthy and slightly unprofessional investigations of the Airy function and assorted Bessel functions; Russ "Haggis" Johnston who never seemed to want to brush up on his magnitudes, Emmanuel "Crane" Ocran for our multi-wavelength studies of the faint radio sky.