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Parts of a Telescope

The telescope is one of the greatest astronomical inventions we have. For those of us who will never be NASA astronauts it is a way for us to get a little closer to the final frontier. Like any tool, in order to utilize its full potential you need to know how it works. By learning the different parts of a telescope and how they work together you can get a better your understanding and appreciation of the instrument that allows us to get up close and personal with the stars.

Telescope Tube
- Perhaps the simplest part of the telescope, the telescope tube is also the most important. Sometimes referred to as the optical tube, it is a hollow tube to which acts as the hub for all the other parts. The tube houses the lenses or mirrors and creates the entire optical system. Tube designs and materials may differ depending on the type of the telescope but the overall design remains the same.
Optical Finderscope
- The Optical Finderscope or viewfinder is attached to the side of the telescope tube. Resembling a mini-telescope, the finderscope enlarges the image area and makes finding objects much easier. It then allows you to center the object or area you are attempting to view in the cross-hairs painted on the glass. If the finderscope is aligned properly with your telescope any image centered in the finderscope will also be centered in the telescope.
Eyepiece
- Simply put, the eyepiece is how you view the image. Eyepieces come in a variety of sizes and designs. When choosing an eyepiece it is important to make sure the barrel size fits your focuser. If it doesn't you may need to purchase an adapter. The focal length of the eyepiece will determine its magnifying power which is measured in millimeters.
Focuser
- Focusers can come in several different styles, but every telescope has one. The focuser holds the eyepiece. It can be moved up and down (on some models it moves left and right) by a knob on the side of the telescope tube. This movement adjusts the inner tube and the eyepiece until the image is brought into focus.
Reflecting Mirrors
- In a reflection telescope the image seen through the eyepiece is created by primary and secondary mirrors. These curved mirrors collect the light and through a series of reflections the light is manifested as an image.
Refracting Lenses
- Refracting telescopes work in a similar way to reflecting telescopes, save one difference. Inside the tube, rather than mirrors there are a series of lenses that collect the light and magnify it to create an image seen through the eyepiece.
Mount Assembly
- The Mount Assembly is comprised of a series of parts that supports the telescope tube and allows it to be positioned safely. The mount is also what attached the telescope to a tripod.

Astronomy