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Optical & Mechanical Parts of a Telescope

Telescopes come in all shapes and sizes. The refracting telescope was fabricated by Galileo and is still among the most commonly used telescopes today. The technology used in refracting telescopes is similar to what&'s used binoculars and telephoto lenses on cameras, and it consists of optical and mechanical parts.

Optical Tube Assembly
- The optical tube assembly is the main tube of the telescope, complete with an objective lens for gathering light in the front and a secondary lens for magnification in the back. The back of the tube assembly is also home to the eyepiece, which can sometimes contain extra individual lenses.
Finder
- The optical finder acts as a miniature telescope that mounts to the telescope tube. It allows you to localize objects at a lower magnification before you magnify them further with the main telescope.
Focuser
- The focuser attaches to the eyepiece of the telescope tube. The focuser moves the internal tube of the tube assembly to move the secondary lens, usually by adjusting a knob on the focuser. This focuses the magnified image.
Mount
- The mount allows you to move the telescope on the tripod. The two main types of mounts are equatorial, which allows the telescope to rotate on an axis parallel to the Earth&'s axis of rotation, and the altazimuth, which allows the telescope to move along two perpendicular axis of motion: vertical (altitude) and horizontal (azimuth).

Astronomy