This is the second of a series of articles about astronomy equipment to help you decide what you might like. If you have questions about a specific piece of equipment, and how it compares to alternatives, send a note to me at and I'll see what I can find out.

Now that we have considered the telescope itself, let’s focus on the eyepieces. There are many things to consider.

Rule #1: Buy quality optics the best optics you can afford. Even if you upgrade your telescope in the future to bigger or better, wouldn't it be nice to take your eyepieces along with you?

Rule #2: Size matters. The larger the diameter of the eyepiece, the more comfortable it will be to use. Of course it will also be more expensive. Eyepieces come in three standard barrel sizes: 0.965 inches, 1.25 inches, and 2.0 inches. I recommend avoiding 0.965 inch eyepieces. They are just too small to provide a comfortable and satisfactory observing experience. 1.25 inch eyepieces are common, high quality, and reasonably priced. 2.0 inch eyepieces are heavenly for observing heavenly bodies. Many astronomers have some of both. Remember, if you have any 2.0 inch eyepieces the hardware between the telescope and the eyepiece will have to be 2.0 inch compatible. You will use a converter to use your 1.25 inch eyepieces. I have all 1.25 inch eyepieces. If cost was not an issue, I would use all 2.0 inch eyepieces.

Rule #3: Which ones to get? Different eyepieces will give you different magnifications. To determine magnification, divide the focal length of the telescope by the focal length of the eyepiece. So a 2000mm focal length telescope with a 25 mm focal length eyepiece will have a magnification of 80. You want an assortment (see Rule #4).

Rule #4: Buy a good quality 2-x Barlow Lens. This effectively doubles the number of lenses that you have. If you have a 25 mm focal length lens and you have a 2-x Barlow, together they make a 12.5 mm focal length lens. Choose your lenses accordingly. Different magnifications will perform better for different objects and under different seeing conditions. It is convenient and rewarding to have an assortment.