The ASTELE 133.5 is an excellent astronomical telescope for observing the heavens. Its optical design is Maksutov Cassegrain. Its diffraction-limited optics are multi-coated, and this makes ASTELE 133.5 a great instrument for doing astrophotography delivering pin-point images over a 35mm format.If you are looking for a telescope with superb optics that is easy to setup, the ASTELE 133.5 is that and more. It is ideal for a professional or an advanced amateur astronomer.The ASTELE 133.5 uses U.S. standard 1.25" O.D.-sized eyepieces (hundreds are available).