Better telescopes have eyepiece barrels that are 1 inches in diameter. This larger size can make a world of difference in the view, and they are more expensive. The eyepiece and the focal length of the telescope determine the power each eyepiece will give. Refractors, reflectors Telescopes come in two basic types. Refractors use a large front lens to gather light.
Reflectors use a curved mirror located at the bottom end of the telescope.
Both are good designs, but a larger reflector can be purchased for the same money as a smaller refractor. Refractors offer permanent optical alignment while reflectors need periodic but simple adjustment. Put simply, reflectors can show you more for less money. Again, the best of each come with focusers that accept 1 -inch diameter eyepieces. The minimum size for refractor objectives should be considered 3 inches.