So a f/1.8 on a 1" sensor would still gather more light than a f/3.5 on an APS-C?

Bob A L wrote:

Maybe on your cameras, but if I set my 1" sensor camera at f1.8, 1/60 sec. iso 100 and my apsc camera at f3.5, 1/60 sec. iso 100, and photograph the same subject illuminated by the same light, the photo from the apsc camera will be much darker than the one from the 1" camera. Then I either would live with the darker photo, which might have even more noise than the one 1" sensor because of the dark image. Or, I could employ post processing techniques to raise the lightness in the apsc shot to equal the shot from the 1" sensor or lower the lightness in the 1" sensor to equal the lightness of the apsc sensor shot, and possibly add noise in either case due to the post processing. But the difference in noise could vary simply because of sensor size or design. But then again, at my example of 100 iso, neither one would likely have much of a noise problem unless it was created by post processing.

But you’d use iso400 on the Apsc and that way the lightness, DoF and noise would be almost the same.