Joe,
that's been exactly my point: Isn't that "speed" from 1 or 1,5 stops plus of such a limited field of use that it isn't much more than an speed illusion ? Fine if I WANT that super narrow DOF, but what if do NOT want it, or if it is even contraproductive ?
I mean the price of DOF you pay with faster lenses is very different from the price of a bit more grain or, within the limits valid for moving objects , from a slower shutter time.
I've been out quite often with the 50 Nokton at night and it did not take much time to learn that the 1,5 stops plus are good for nothing, excepted you got any object in the foreground you can focus on, and if you accept to get all the rest OOF.
Otherwise you have to take a mono- or tripod as well as the owner of a slow lens has to take it. That is what I mean with limited field of use.
I'd say "speed" is simply the wrong word in this context. If at all the fast lenses are good for anything it is IMO for narrow DOF, but not for low light. Even in this case tho the much more compact f2 lens does that good enuff, who really needs the super narrow DOF of a f1,4 lens , not to speak of the f1,2 or f1,0 monsters ? Who uses f1,0 and for what to do what could not be done with a F2 lens ???
A fellow pro photog once told my 98% of all fast lenses would be bought because they look more impressive, and the more I look at my Nok I am afraid I stepped exactly into this kinda prestige trap ?
Best,
Fitzi