I agree on your first point, it is the amount of light coming in through the aperture. A wide open aperture lets more light in. The point is just that they hav

I agree on your first point, it is the amount of light coming in through the aperture. A wide open aperture lets more light in. The point is just that they have to balance DOF and brightness in their designs. It’s a multi-variable equation, and sensor size is one of the factors that constrains the options you have available all things considered. Like you said > once you fix the angle of view. And of course they’re limited to relatively small apertures anyway. > Because films with higher ISOs are unacceptably grainy for most uses. Not in my experience! This is just nitpicking now. We can keep getting more and more technical, but I think you understand how it works. You’ve made your point. You don’t like gatekeeping. I’m not gatekeeping.