Terminology

Eyepieces

EyepiecesWith the telescope's primary optics (objective lens, primary mirror, or a combination of lenses and mirrors) having formed an image at the telescope's focus, the purpose of the eyepiece (consisting of two or more small lenses mounted in a metal barrel) is to magnify this image. Eyepieces are available in a wide range of optical configurations, barrel diameters, and focal lengths. It is the focal length of the eyepiece, in conjunction with the focal length of the main telescope, that determines the operating power of the eyepiece. (See How to Calculate Power)

Eyepieces: Meade telescopes include eyepieces to magnify objects seen through the telescope. Wide field eyepieces permit finding and observing objects with great clarity and ease. High power eyepieces may be used under favorable conditions to increase image size for more detailed observations.

Barlow LensThe Barlow Lens: Inserted into the telescope in front of the eyepiece, the Barlow lens effectively multiplies the focal length of the main telescope

A 2X Barlow lens doubles the main telescope's effective focal length, thereby doubling the power of each eyepiece used with the Barlow.


Diagonal MirrorDiagonal Mirrors, Erecting Prisms, and Viewfinders:
A variety of telescope accessories are either supplied as standard equipment or available optionally, depending on the telescope model.

Diagonal Mirrors: When observing objects nearly overhead through refracting or mirror-lens telescopes, the diagonal mirror (or in some cases, diagonal prism) permits a comfortable observing position. The diagonal mirror diverts light out to a right-angle to the telescope's main tube. All Meade refractors and mirror-lens telescopes include a diagonal mirror or prism for this purpose. Examples: NG70-SM, 90AZ – ADR, DS2080 AT-TC, ETX90 AT-TC, and ETX125 AT-TC.

 


Viewfinders:
Most telescopes have rather narrow fields of view. As a result, finding and centering an object in the telescopic field can be difficult unless a viewfinder is used. The viewfinder is a small, low-power, wide-field telescope, usually equipped with internal crosshairs for easy object-sighting. With the viewfinder aligned parallel to the main telescope, objects first located in the viewfinder are then also in the main telescope's field.

The Red Dot Viewfinder: Because the main telescope has a fairly narrow field of view, locating objects directly in the main telescope can sometimes be difficult. The red dot viewfinder projects a small red dot that permits you to more easily locate objects. When the red dot viewfinder and optical tube are aligned to each other, both point to the same position in the sky. An object located in the viewfinder is therefore in the eyepiece of the main telescope.

Tripod: A rigid, full-length field tripod is used to support the telescope and is adjustable to allow standing or seated observations through the telescope.

Astronomy Software:
Meade Telescopes include AutoStar®Suite Astronomer Edition Software on DVD AutoStar Suite Astronomer Edition software will help you learn the night sky. It displays more than 10,000 celestial objects including planets, stars, galaxies and nebulas. You can print out star charts and even plan your observing sessions. It operates on any Windows®based PC.

Also includes an Instructional DVD. You’ll be up and running in no time.

Telescope Mountings

Altazimuth MountingOnce an object, whether terrestrial or astronomical, is located and centered in the telescope's field of view, the telescope's mechanical mounting permits the observer to track, or follow, the object as it moves across the landscape or sky. Types of telescope mountings include the following:

Altazimuth Mountings:
The simplest type of telescope mount allows the telescope to be moved up-and-down (in vertical, or altitude) and left-to-right (in horizontal, or azimuth). The altitude-azimuth (altazimuth) mounting thus permits the observer to follow objects by simple motions of the telescope in vertical and horizontal. Slow-motion controls, can facilitate these motions. The altazimuth mount, owing to its simplicity and relatively lower cost, is widely used with telescopes in both land-viewing and astronomical applications. Example: Meade NG70-SM and 90AZ – ADR.


Equatorial MountingsEquatorial Mountings:
Although celestial objects are essentially fixed in their positions in the sky (on the celestial sphere, the imaginary spherical surface on which all astronomical objects are located), they appear to move in an arc across the sky, as the earth rotates underneath the sky once every 24 hours. From an astronomical point of view, therefore, the task of the telescope mounting is to compensate for the Earth's rotation and allow the observer to track the Moon, planets, and stars. This task is made vastly easier by the equatorial mounting, the type of mounting incorporated into most larger or more advanced telescopes. By aligning one axis of the equatorial mount to the Earth's rotational axis (a simple process which involves pointing one telescope axis to the North Star), the observer can track astronomical objects by turning one control cable, instead of the two simultaneous motions required with the altazimuth mount. If a small motor is attached to the equatorial mount, this tracking can be performed automatically. These motor drives are available for most Meade equatorially mounted telescopes. Example: 114EQ-ASTR.

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