Thanks Bojan and Susan, good stuff.
“ … is comparable in performance with equivalent Canon at f5.6” [Bojan] Yes, well, maybe so, but I image one is paying the top dollar for good performance half- or one-stop down from f/1.4 or F/2 in the fast Canon lenses.
I do admire the brave folks who even just think about modifying lenses, let alone doing it!