Magnification Many people, especially those new to telescopes, are under the false impression that the higher the magnification, the better the telescope. It's true that as the power of a telescope increases, the apparent size of whatever is in view grows larger, but what most people fail to realize is that at the same time, the images become fainter and fuzzier. Finally, as the magnification climbs even higher, image quality becomes so poor that less detail will be seen than at lower powers. It's easy to figure out the magnification of a telescope. This is the focal length of that particular eyepiece expressed in millimeters.
Magnification is calculated by dividing the telescope's focal length by the eyepiece's focal length.
There are 25.4 millimeters in an inch.