Leica.overgaard.dk seems to disagree with your definition. Summicron was derived from Leicas use of crown glass for the first time.
ALL Summicrons are f2 maximum aperture.
-M says it's an M mount lens not an R or reflex lens
Not all Summicrons have finger tabs, in fact MOST do not.
Point proven... Confusing...
~Stone | Sent w/ iPhone using Tapatalk
~Stone | "...of course, that's just my opinion. I could be wrong."~Dennis Miller