Meade Tripod LX90-ACF 10 inch User Manual - Page 14
Choosing an Eyepiece
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14 NEVER point the telescope directly at or near the Sun at any time! Observing the Sun, even for the smallest fraction of a second, will result in instant and irreversible eye damage, as well as physical damage to the telescope itself. NOTE: For a list of magnification ratings of the eyepieces available for the LX90 telescope, see OPTIONAL ACCESSORIES, page 42. 4. Remove the dust cap from the rear cell of the telescope. Thread the eyepiece holder into the rear cell thread. Slide the diagonal prism into the eyepiece holder and lock in place by turning the thumbscrew to a firm feel. 5. Remove the Super Plössl 26mm eyepiece (Pg. 7, Fig. 1, 1) from its container and place it in the diagonal prism (Pg. 7, Fig. 1, 3). Tighten the thumbscrew (Pg. 7, Fig. 1, 2) to a firm feel only. 6. Remove the dust cover (Pg. 7, Fig. 1, 15) from the optical tube assembly (Pg. 7, Fig. 1, 5) by gently prying it off. Choosing an Eyepiece A telescope's eyepiece magnifies the image formed by the telescope's main optics. Each eyepiece has a focal length, expressed in millimeters, or "mm". The smaller the focal length, the higher the magnification. For example, an eyepiece with a focal length of 9mm has a higher magnification than an eyepiece with a focal length of 26mm. Your telescope comes supplied with a Super Plössl 26mm eyepiece, which gives a wide, comfortable field of view with high image resolution. Low power eyepieces offer a wide field of view, bright, high-contrast images, and eye relief during long observing sessions. To find an object with a telescope, always start with a lower power eyepiece such as the Super Plössl 26mm. When the object is located and centered in the eyepiece, you may wish to switch to a higher power eyepiece to enlarge the image as much as practical for prevailing seeing conditions. For information about optional eyepieces for the LX90, see OPTIONAL ACCESSORIES, page 42. NOTE: Seeing conditions vary widely from night-to-night and site-to-site. Turbulence in the air, even on an apparently clear night, can distort images. If an image appears fuzzy and ill-defined, back off to a lower power eyepiece for a more well-resolved image (Pg. 16, Fig. 7). The power or magnification of a telescope is determined by the focal length of the telescope and the focal length of the eyepiece being used. To calculate eyepiece power, divide the telescope's focal length by the eyepiece's focal length. For example, a 26mm eyepiece is supplied with the LX90. The focal length of the 8" LX90 is 2000mm (see SPECIFICATIONS, page 47). Telescope Focal Length 2000mm Eyepiece Focal Length 26mm 2000 ÷ 26 = 77mm The eyepiece power, or magnification, is therefore 77X.