Installing the Diagonal

The diagonal is a prism that diverts the light at a right angle to the light path of the refractor. This allows you to observe in a position that is more comfortable than if you looked straight through. This diagonal is an erect image model that corrects the image to be right side up and oriented correctly left-to-right which is much easier to use for terrestrial observing. Also, the diagonal can be rotated to any position which is most favorable for you. To install the diagonal and eyepieces:

1.Insert the small barrel of the diagonal into the 1.25” eyepiece adapter of the focus tube on the refractor – Figure 2-13. Make sure the two thumbscrews on the eyepiece adapter do not protrude into the focuser tube before installation and the plug up cap is removed from the eyepiece adapter.

Installing the Eyepieces

Figure 2-13 – Diagonal with Eyepiece

The eyepiece (or ocular) is an optical element that magnifies the image focused by the telescope. Without the eyepiece it would be impossible to use the telescope visually. Eyepieces are commonly referred to by focal length and barrel diameter. The longer focal length (i.e., the larger the number) the lower the eyepiece magnification (i.e., power). Generally, you will use low-to-moderate power when viewing. For more information on how to determine power, see the section on “Calculating Magnification”.

1.Put the chrome barrel end of the 40mm eyepieces into the diagonal and tighten the thumb screw. Again, when doing this make sure the thumb screw is not protruding into the diagonal before inserting the eyepiece.

2.The eyepieces can be changed to other focal lengths by reversing the procedure in step 2 above.

Attaching the Finderscope

To align the finderscope with the telescope you must first mount the finderscope to the telescope. To install the finderscope:

1.Slide the finder bracket (attached to the finderscope) into the mounting bracket on the telescope.

2.The finderscope bracket will slide in from the back. The finderscope should be oriented so that the objective (larger) lens is toward the front end of the telescope.

Figure 2-14

3.Tighten the set screw on the mounting bracket to hold the finderscope in place.

Aligning the Finderscope

Accurate alignment of the finder makes it easy to find objects with the telescope, especially celestial objects. To make aligning the finder as easy as possible, this procedure should be done in the daytime when it is easy to find and identify objects. The finderscope has a spring-loaded adjustment screw that puts pressure on the finderscope while the remaining screws are used to adjust the finder horizontally and vertically. To align the finder:

1Choose a target that is in excess of one mile away. This eliminates any possible parallax effect between the telescope and finder.

2Release the mounts locking clamps and point the telescope at your target.

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Celestron Scope 90 Installing the Diagonal, Installing the Eyepieces, Attaching the Finderscope, Aligning the Finderscope
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Scope 90 specifications

The Celestron Scope 90 is a powerful refractor telescope that combines portability, performance, and user-friendly features, making it an excellent choice for both novice and experienced astronomers. This telescope is designed to provide impressive views of celestial objects, from the craters of the Moon to distant planets and star clusters.

One of the standout features of the Celestron Scope 90 is its 90mm aperture, which allows for significant light-gathering capacity. This means that users can enjoy brighter and clearer images of various astronomical phenomena. The telescope employs high-quality optics with fully coated glass lenses that enhance image contrast and clarity, ensuring a pleasurable viewing experience.

Another notable characteristic of the Celestron Scope 90 is its compact and lightweight design. Weighing in at just a few pounds, it is easily portable, making it ideal for stargazing on the go or for backyard observing. The included adjustable aluminum tripod offers stability without adding excessive weight, contributing to the telescope’s ease of transport.

The telescope features a simple yet effective altazimuth mount, making it straightforward to point at objects in the sky. The mount allows for smooth movement in both horizontal and vertical directions, giving users the freedom to track celestial objects with ease. Additionally, Celestron includes a StarPointer finderscope that helps users locate their desired targets quickly and efficiently.

Furthermore, the Celestron Scope 90 is equipped with two eyepieces, offering different magnification levels to enhance viewing versatility. This allows users to switch between low and high magnification for various astronomical objects. Whether observing the rings of Saturn or the details of a distant galaxy, the Celestron Scope 90 provides a rich viewing experience.

Celestron has also integrated advanced technologies into the Scope 90, including a robust build quality that enhances durability. The telescope's design is made to endure various weather conditions, making it suitable for field use. It's also compatible with optional accessories, such as solar filters and additional eyepieces, allowing users to expand their astronomical observations.

In summary, the Celestron Scope 90 stands out as a compact, powerful, and user-friendly telescope. With its impressive optics, portability, and advanced features, it caters to a wide range of astronomical interests, making it a reliable companion for anyone eager to explore the wonders of the night sky. Whether you're just starting your stargazing journey or are an experienced astronomer, this telescope offers the capabilities you need for an enjoyable and rewarding experience.
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