Wallet full of $100 bills

[Jon Ruyle]

But even if the apertures are the same and the DOF is the same, doesn't bellows factor mean the larger sensor will get less light (and therefore have more noise for the same DOF)?

No.


While it is true that the bellows factor has a greater effect on the larger sensor than the smaller, thus giving it slower exposure (as compared to what you would expect if you didn't take bellows into account), it also has a greater effect on DOF in the larger sensor than the smaller. The two effects cancel exactly.


I did some calculations to convince myself that this is true (or maybe I did the calculations for diffraction, I don't remember exactly), but a friend (who isn't in to photography but is a lot smarter than I am) pointed out an easier way to see this. With a given framing and subject distance, DOF, diffraction, and exposure are all a functions of aperture alone, and thus in the battle between DOF and exposure time or DOF and diffraction, sensor size does not matter at all.

[Daniel Browning]

That