The right choice of the optical system of the telescope is determined by your preferences. Basically the telescope optical system delivers a brighter image when it is bigger. With a 80mm ED-APO you will see brilliant views of the moon. For the planets we recommend a aperture minimum of 102mm. Bigger telescopes enable you to see even further – you can gaze at objects outside our solar system, like other stars, globular star clusters, galaxies, emmission nebulae, reflection nebulae and groups of galaxies. There are a number of different types of optical systems for telescopes: Maksutov-Newton, Ritchey-Chrétien, Dall Kirkhams, Schmidt-Cassegrains, Newtons, Fraunhofer, Apochromats, ED-Apos, etc. All those telescopes fall into one of three categories: refractors (telescopes made with lenses), reflectors (telescopes made with mirrors) and catadioptric telescopes (telescopes made with lenses and mirrors). Which of those types is best for you is connected to your needs. Our ED-Apos for example are very compact and easy to transport. They also do not only perform well for visual work, but also for astrophotography with DSLRs or CCD-cameras.