Focusing, Calculating Magnification | Celestron Scope 90 guide

A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is focused. Some telescopes, known as refractors, use lenses, .and other telescopes, known as reflectors (Newtonians), use mirrors.

Developed in the early 1600s, the refractor is the oldest telescope design. It derives its name from the method it uses to focus incoming light rays. The refractor uses a lens to bend or refract incoming light rays, hence the name (see Figure 3-1). Early designs used single element lenses. However, the single lens acts like a prism and breaks light down into the colors of the rainbow, a phenomenon known as chromatic aberration. To get around this problem, a two-element lens, known as an achromat, was introduced. Each element has a different index of refraction allowing two different wavelengths of light to be focused at the same point. Most two-element lenses, usually made of crown and flint glasses, are corrected for red and green light. Blue light may still be focused at a slightly different point.

Figure 3-1

A cutaway view of the light path of the Refractor optical design

Focusing

To focus your telescope, simply turn the focus knob located directly below the eyepiece holder (see Figures 1-1). Turning the knob clockwise allows you to focus on an object that is farther than the one you are currently observing. Turning the knob counterclockwise from you allows you to focus on an object closer than the one you are currently observing.

Note: If you wear corrective lenses (specifically glasses), you may want to remove them when observing with an eyepiece attached to the telescope. However, when using a camera you should always wear corrective lenses to ensure the sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times.

Calculating Magnification

You can change the power of your telescope just by changing the eyepiece (ocular). To determine the magnification of your telescope, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the formula looks like this:

Focal Length of Telescope (mm)

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.