Telescope
 The astronomical telescope is the most basic instrument of astronomy,  and it is also a necessary observation tool for the majority of astronomy popularization workers and astronomy lovers.     According to the structure of the objective lens, the optical system of  the astronomical telescope can be roughly divided into three categories:  the lens as the objective lens, called refracting telescope; Using a mirror  as an objective lens, called a reflecting telescope; A telescope that contains  both a lens and a mirror is called a reflector. Some astronomy enthusiasts  often buy a lens, thinking that this solves the objective problem of the telescope.  In fact, one lens imaging will produce aberration, now, the normal refraction  telescope objective is mostly composed of two to four lenses. In contrast,  refraction telescopes are widely used and easy to use, so they are more suitable for astronomical popularization. ,   ...