If you are faced with the need to choose binoculars, then you probably already noticed that modern binoculars have either a direct design or offset. In the first case, the binoculars are similar to 2 spotting scopes fastened together. The second type has an offset shape. A roof prism system is a type of prism […]

A refractor, or a lens telescope, is the oldest type of telescopes. It was invented in 1609 by Galileo Galilei and was updated in consequence. Firstly, a refractor used two lenses: convex as an objective and concave in an eyepiece, that caused spherical and chromatic aberrations. This scheme was supplemented by a second lens of […]