Image orientation through the finder will be inverted (i.e., upside down and backwards left-to-right). This is normal for any finderscope that is used straight-through. Because of this, it may take a few minutes to familiarize yourself with the directional change each screw makes on the finderscope.

Telescope Basics

Calculating Magnification

The magnification (or power) of a telescope is variable depending upon the focal length of the eyepiece being used along with the focal length of the telescope.

To calculate the magnification we use the following formula:

Magnification = FL(telescope)

FL(eyepiece)

where FL(telescope) is the focal length of the telescope and FL(eyepiece) is the focal length of the eyepiece. For example, if the focal length of the telescope is 910mm and you use a 20mm eyepiece your magnification is 910/20 = 46x.

There are numerous optional eyepieces that are available to expand your range of magnification. There are various types of eyepieces of varying quality to choose from.

The Celestial - Coordinate System.

The celestial-coordinate system is an imaginary projection of the Earth's geographical coordinate system onto the celestial sphere which seems to turn overhead at night. This celestial grid is complete with equator, latitudes, longitudes and poles.

The Earth is in constant motion as it rotates on its axis. Actually the celestial-coordinate system is being displaced very slowly with respect to the stars. This is called precession and is caused by gravitational influences from the Sun, Moon and other celestial bodies.

The celestial equator is a full 360º circle bisecting the celestial sphere into the northern celestial hemisphere and the southern celestial hemisphere. Like the Earth's equator, it is the prime parallel of latitude and is designated 0º.

The celestial parallels of latitude are called "coordinates of declination (Dec.)", and like the Earth's latitudes they are named for their angular distances from the equator. These distances are measured in degrees, minutes and seconds of arc. There are 60 minutes of arc in each degree, and 60 seconds of arc in each arc minute. Declinations north of the celestial equator are "+" and declinations south are "-". The north pole is +90 and the south pole is -90 .

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Celestron 91510 instruction manual Calculating Magnification, Celestial Coordinate System
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91510 specifications

The Celestron 91510 is a remarkable telescope that offers astronomy enthusiasts a blend of quality, portability, and advanced features, making it a popular choice for both beginners and seasoned stargazers alike. Known for its impressive optics, the Celestron 91510 utilizes a 70mm refractor design that provides bright and clear images, ideal for observing celestial objects such as planets, stars, and deep-sky phenomena.

One of the standout features of the Celestron 91510 is its fully coated optics, which enhance light transmission and improve image quality. This ensures that users can observe fine details in celestial bodies, such as the rings of Saturn or the craters on the Moon. The telescope comes with two eyepieces of different focal lengths, allowing for varying magnification. This versatility enables users to explore the night sky with ease, offering both wide-field views of star clusters and higher magnification for detailed observations.

Portability is another significant advantage of the Celestron 91510. Designed with travel in mind, this telescope is lightweight and compact, making it easy to set up and transport. It features a sturdy yet portable mount that provides stable support during observations. The pan-and-tilt head allows for smooth tracking of celestial objects, ensuring that users can focus on their targets without hassle.

Moreover, the telescope includes a red dot finder which aids in locating objects quickly in the night sky. This user-friendly feature is especially beneficial for beginners who may find it challenging to navigate the stars. The adjustable tripod provides a stable base and can be set to various heights, ensuring comfort during extended viewing sessions.

Celestron's commitment to quality and innovation is evident in the design of the 91510. It incorporates durable materials that withstand the rigors of outdoor use, ensuring longevity. Additionally, the telescope's overall aesthetic appeal, complete with a sleek design, adds to the enjoyment of using this astronomical instrument.

In summary, the Celestron 91510 is an excellent choice for anyone looking to delve into the wonders of astronomy. With its high-quality optics, user-friendly features, and portability, it offers an enjoyable stargazing experience. Whether you are a novice wanting to explore the cosmos or an experienced astronomer seeking a reliable companion, the Celestron 91510 stands out as an exceptional option.
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