ReneeS said:
Eye pieces are the small lenses that you look through when using a telescope. They are important because they determine the magnification and clarity of the image you see.
The recommended size or focal length for eye pieces for a beginner is between 25mm-10mm. This range will provide a good balance between magnification and field of view.
For a beginner, a Plössl or Kellner eye piece is recommended. These types of eye pieces offer good quality images and are relatively affordable.
No, not all eye pieces are compatible with all telescopes. It is important to check the specifications of your telescope before purchasing an eye piece to ensure compatibility.
Other factors to consider include the eye relief, which is the distance between the eye piece and your eye, the field of view, and the type of telescope you have (refractor, reflector, or catadioptric).