How much more light can a telescope with an objective that is 48 inches in diameter gather when..(continuted)?

The light gathering power of a telescope depends on the size of the objective. The important part of the size isn't just the diameter but the area of that objective. The area of a circle is: π * r * r (That's not the proper notation of the formula but I can't seem to figure out how to superscript in this forum. The "r" should be squared.)

So the area for a 48 inch objective is roughly 1809 inches. The area for a 29 inch objective is roughly 660 inches. That works out to be about 2.74 times more light gathering power for the 48 inch verses the 29 inch.

Hope that helps!

Light-gathering power is a function of the square of the diameter. So a telescope that has an objective twice the size of a smaller telescope will have 4x the light-gathering power.

So the math for this particular problem goes (48/29)² =