▲ Advantages:
Because the cost of reflectors is much lower than that of lenses, for large-aperture telescopes, they are often made reflective rather than bulky refractive. The portable design of the reflective telescope, although the lens barrel is only 500mm, but the focal length can reach 1000mm. The focal ratio of the Newtonian mirror can reach f / 4 to f / 8, which is very suitable for observing those faint extragalactic galaxies and nebulae. Sometimes it is also appropriate to use this telescope to observe the moon and planets. If you want to take pictures, it is very good to use Newtonian telescope. But it is a little more troublesome to use than folding telescope. The Newtonian structure can converge the light well and get a very bright image at the focal point.
▲ Disadvantages:
Open lens-type air can be circulated, which not only affects the stability of imaging, but also some dust will enter the lens tube with the flowing air and attach to the objective lens. In the long run, the coating on the surface of the objective lens will be damaged to make it reflective decline. Since the objective lens of this structure is relatively easy to break, you need to be careful when using it. For off-axis light, the Newtonian telescope produces coma. This type of telescope is not suitable for observation of ground landscape. Newton-style telescopes usually have large diameters and large volumes, so they are expensive. Due to the addition of a secondary plane mirror, some light will be lost.
▲ Instructions for cleaning mirror surface:
First blow off the dust that can be blown away with a blower, then use a good quality cotton wool to dip alcohol and gently wipe the mirror surface. After drying, look at the light source from the side to see if there are some cotton filaments or water stains left on it Only use some good quality lens cleaning cloth to wipe gently (be careful, otherwise it will affect your telescope).