Light gathering in M43 vs FF

It's a sunny day, not a cloud in the sky, lets say you are in a room, the blinds to a small window are shut, the room is pitch black. Now compare the amount of light the room has if you were to open the blinds a quarter of the way versus when you have the blinds fully open.

It's not a perfect analogy, but there are people here who believe that the room will be equally lit in both scenarios - that by having the blinds open a quarter of the way, that more light will be focused onto that smaller area thus resulting in equal total light.