This a project to make a popular Newtonian-design reflector telescope with a Dobsonian mount. The principle of the telescope is to collect light and then magnify the image. The light from a distant object (a star or planet) is gathered by the mirror and brought to a focal point. The eyepiece is used to focus and enlarge the image. By changing the eyepiece, we can increase the magnification and the size of the image. The larger the objective or mirror the more light it can gather and therefore you can use a higher magnification eyepiece.