The magnifying power of a telescope will change depending on the focal length of the eyepiece you are using. A more appropriate question may be to ask how much light-gathering power does a telescope have. Light gathering power is a telescope's ability to see faint, distant objects and is solely determined by the aperture of the telescope's main mirror or lens. The larger the aperture, the more light-gathering power a telescope has. Remember it's the entire surface area of the telescope's main mirror or lens that is collecting the light; therefore every time a telescope's aperture is doubled, the light-gathering power is increased by a factor of 4 times!
