Eyepiece Adapter
Erect Image Diagonal
Figure 2-4– Visual accessories for NexStar 80 GTL

The Eyepiece

The eyepiece, is the optical element that magnifies the image focused by the telescope. The eyepiece fits either directly into the focuser or into the diagonal. To install the eyepiece:

Eyepiece

Star Pointer

1.Loosen the thumbscrew on the diagonal so it does not obstruct the inner diameter of the barrel. Remove the protective dust cap from the diagonal's barrel.

2.Slide the chrome portion of the low power 25mm eyepiece into the diagonal.

Focus Knob

3.Tighten the thumbscrew to hold the eyepiece in place.

To remove the eyepiece, loosen the thumbscrew on the diagonal and slide the eyepiece out.

Eyepieces are commonly referred to by focal length and barrel diameter. The focal length of each eyepiece is printed on the eyepiece barrel. The longer the focal length (i.e., the larger the number) the lower the eyepiece power or magnification; and the shorter the focal length (i.e., the smaller the number) the higher the magnification. Generally, you will use low-to-moderate power when viewing. For

more information on how to determine power, see the section on “Calculating Magnification.”

Barrel diameter is the diameter of the barrel that slides into the star diagonal or focuser. The NexStar uses eyepieces with a standard 1-1/4" barrel diameter.

Focusing

To focus your telescope, simply turn either of the focus knobs on the sides of the focuser (see figures 2-4). Turn the focus knob until the image is sharp. Once sharp, turn the knob towards you to focus on an object that is closer than the one you are currently observing. Turn the knob away from you to focus on a more distant object than the one you are currently observing.

The Star Pointer

Finderscope

The Star Pointer is the quickest and easiest way to point your telescope exactly at a desired object in the sky. It's like having a laser pointer that you can shine directly onto the night sky. The Star Pointer is a zero magnification pointing tool that uses a coated glass window to superimpose the image of a small red dot onto the night sky. While keeping both eyes open when looking through the Star Pointer, simply move your telescope until the red dot, seen through the Star Pointer, merges with the object as seen with your unaided eye. The red dot is produced by a light-emitting diode (LED); it is not a laser beam and will

Sight Tube

ON/OFF

Brightness Control

Azimuth

Adjustment

Control

Battery Compartment (not shown)

Dovetail

Tightening

AltitudeScrew

Adjustment

Control

Dovetail Mount

Figure 2-5 – The Star Pointer Finderscope with Bracket

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Celestron 80GTL manual Eyepiece, Focusing, Star Pointer Finderscope
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80GTL specifications

The Celestron 80GTL is a powerful and compact telescope designed for both amateur astronomers and experienced stargazers. It combines modern technology with user-friendly features, making it an excellent choice for those looking to explore the night sky. With its 80mm aperture, the 80GTL captures enough light to reveal a variety of celestial objects, from the moon’s craters to distant galaxies.

One of the standout characteristics of the Celestron 80GTL is its innovative Altazimuth mount. This mount provides smooth and precise movements in both horizontal and vertical directions, allowing users to easily track celestial objects as they move across the sky. The setup is quick and straightforward, making it ideal for beginners who may be intimidated by more complex mounts.

The telescope is equipped with Celestron’s StarScope system, which includes a computer-controlled GoTo mount. This feature allows users to automatically locate and track over 40,000 celestial objects with the push of a button. The included hand controller is intuitive and easy to navigate, giving users instant access to stars, planets, and deep-sky objects. This technology not only enhances the viewing experience but also helps novice astronomers learn about the universe with guided tours through the night sky.

Another notable feature of the Celestron 80GTL is its sturdy construction and lightweight design. Made from high-quality materials, it boasts durability while remaining portable for easy transport. Weighing just under 10 pounds, this telescope can be taken on camping trips or excursions, allowing users to enjoy astronomy in various locations.

Additionally, users will appreciate the 80GTL’s fully coated glass optics which provide excellent image quality and contrast. The included 25mm and 10mm eyepieces offer different magnifications, catering to diverse viewing preferences. Whether observing the rings of Saturn or the detail of lunar landscapes, the 80GTL promises clear and sharp images.

In summary, the Celestron 80GTL is a highly capable telescope, combining an accessible design with advanced technologies. Its user-friendly GoTo mount, quality optics, and lightweight build make it an exceptional option for anyone wishing to delve into the wonders of the cosmos, ensuring both enjoyment and education in the field of astronomy.
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