Re: Back to the original point:
So from a "PRACTICAL" standpoint, I see a 2-stop (SS) advantage, (until noise becomes a factor).
No. Why do you insist on making objectively false statements? There is no such 2 stop advantage. What is the advantage that you are claiming?
The advantage is an f/1.8 lens is "faster" ... because you can use (2-stops) "faster" SS (than f/3.5).
The resultant shallow-DOF used to be the bane of "faster" lenses, (when restricted to FF).
You keep making objectively wrong statements on a beginners forum. That's pretty poor. What stops you using the same SS with an f/3.5 lens on APSC as the f/1.8 on 1" and increasing the ISO to get the same image lightness? You get the same result within 1/3 stop. There is no 2 stop advantage.
Well heck then ... i might as well just get a (fixed f/stop) f/128 lens and i am set for ANY situation ... (only have to change ISO's).
That’s just stupid. Where did I say that for a given sensor the total exposure doesn’t matter?
That is exactly what you said when you stated you can use the same SS on either f/1.8 or f/3.5 (by changing ISO) ... so why not f/128 ???
And yet again you obfuscate and mislead by ignoring the change in sensor size. You don’t seem to understand (or you are deliberately ignoring) that we are comparing two different f/#s on two different sensor sizes and in that scenario there is NO 2 stop advantage.
But the main advantage of larger sensor-size is lower noise (and deeper DOF).
But noise is NOT A FACTOR until noticeably-objectionable.
Well, we're going to hit 150 posts soon, which is unfortunate because Bob A L might have had a road to Damascus moment when he asked if one deliberately used different exposures on different formats. But instead we are wasting posting room with Joe's nonsense.
I'm just popping in at this place to state that, despite Joe's repeated (ad nauseum) insistence to the contrary, noise is a factor even before it become visibly objectionable, because it affects detail, sharpness, clarity, contrast, colour depth and DR before it becomes visibly objectionable as noise.