>>3404987>Deeper DOF at fast apertures equals a significant higher keeper rate.A full frame kit with a -2 stop aperture but +2 stop ISO would give you similar results both in terms of both DoF and resulting IQ, plus the ability to open up the aperture if required. But whether this is worth the extra cost and weight is case-dependent.
The issue with f/1 and less on FF is that you pretty much can't have any keepers *at all* - trying to take shots with tight framing like this will result in around 1' of DoF, which is physically not enough to fit a human unless they're standing still facing the camera.
