Originally Posted by camrydriver111
Low light shooting has more to do with the size of the lens than megapixels or processing.
Cell phones still suck at it because the lens is so tiny.
Current DX and FX CMOS sensors have amazingly good high ISO capabilities.
I'll take my D800 up to ISO 6400 without even thinking about it, and I can print a beautiful 8x10 from it. The backlit sensor in the D850 is probably a stop better, and the sensor used in the D4/Df is still freakishly good. A Df at 25,600 is probably as good as my D800 at 6400.
The only real reason to use fast lenses these days is for shallow DOF. Cameras like the D800 have made me realize just how little DOF an f/1.4 lens has wide open, and also how difficult it is to actually focus them correctly in low light(something that you won't notice on Tri-X or your typical 400 ASA color print film). Between being able to use ISO 6400 without too much worry and VR(as long as I don't need to stop action) I can usually get away with a fixed f/4 zoom, or-horror of horrors-a variable aperture zoom that hovers around f/4. Even when I need to stop action, I rarely want to go past f/2.8 for DOF and focus accuracy reasons.
And yes, I have Nikkors as fast as f/1.2(although I don't have a Noct) and plenty of both AF and MF primes in the f/1.4-f/2 range
I'd also argue that the real issue with cell phone cameras is the physical size of the sensor. The optic actually are quite amazing given what they're able to resolve onto such a tiny, dense sensor-they're a lot more demanding of good optics than even something like a 24mp DX-sized sensor.