[The_bluester (Paul)]

You can look at it that way to a degree, a faster ratio with the same objective diameter means a steeper light cone, but that does not add any light to what is already on the sensor, it moves light from objects that was missing the sensor on to the sensor by compressing the view - expanding the field of view. Stuff that was just missing the sensor now falls on to it, everything that was already visible occupies less sensor area and that compression in size delivers the same number of photons per hour from any object (Use a single star as an example) to a smaller area of the sensor, so less pixels divvy up the same amount of photons per unit of time between them.