Most telescopes, and all large telescopes, work by using curved mirrors to gather and focus light from the night sky. The first telescopes focused light by using pieces of curved, clear glass, called lenses. ... The bigger the mirrors or lenses, the more light the telescope can gather.

What does 40x mean on a telescope?

Magnification = Telescope focal length ÷ Eyepiece focal length. For example, if you use a telescope of 1000mm focal length with a 25mm eyepiece, the magnification would be 40x (1000mm ÷ 25 = 40). Doubling the power gives you one-fourth the image brightness and reduces the sharpness by one half.

What is wrong with lenses in telescopes?

Limitations of Refracting Telescopes

Lenses create a type of image distortion known as chromatic aberration. ... In addition, lenses in telescopes can only be supported around the outside, so large lenses can sag and distort under their own weight. All of these problems affect image quality and clarity.