Don Pensack: Hi I am Don Pensack with Scope City and today we are talking about how to select and use a telescope? This topic will be on basic telescope usage. Once you have your new telescope out under the stars how do you use it? And how do you use those accessories that you have purchased with the telescope? The first and most basic thing is the eyepiece. The eyepiece is simple lens that can be inserted in the telescope and the focal length of the eyepiece lens tells you what magnification can be produced in the telescope.
Typically, a beginner will have about three telescope eyepieces to begin with, but you can get by with a little bit less, if you use a device known as a Barlow lens. A Barlow lens is a simple negative lens that can be inserted in the telescope in advance of the eyepiece. When the eyepiece is inserted in that eyepiece's power is doubled. Since it doubles the power of any eyepiece that you use with the telescope, having only two eyepieces will give you four magnifications. And then, when you are looking at objects in the night sky, whether it's the moon, the planets, deep sky objects; filters are available to help you see details in those objects. Coloured filters are the type they stand out best for looking at the planets and the moon. Nebula filters will help you see contrast in the Nebulas at the night sky. Filters are one of the most useful accessories that a beginner can purchase.
So now you've got all of the accessories, you've got the telescope, you've got the idea down on how to insert the eyepiece in the telescope. How do you aim the telescope at an object in the night sky? This is a simple mount known as an equatorial mount and an equatorial mount can be moved in a North-South direction, or can be moved in an East-West direction. Both of those directions will enable you to get to any spot of the night sky and find any object. That star atlas we mentioned earlier can enable you to choose just exactly what direction is necessary to go to that object in the night sky.
So this is the simplest usage, then there is a computerized telescope which is lined up on three stars in the night sky once its lined up on those three stars, it knows where it is and knows where it is pointed and you simply enter the numbers of an object into the hand controller to make the telescope go to the next object. And so that's the simplest way to use a telescope under the night sky. The next thing we'll talk about is what you can see in the night sky with that telescope now that you know how to use it.