User manual CELESTRON C60-E

[. . . ] 8 Installing the Counterweight Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Installing the Counterweight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Attaching the Hand Control Holder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Attaching the Slow Motion Knobs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] 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 4-1 A cutaway view of the light path of the Refractor optical design Image Orientation It should be noted that the image orientation will change depending on the viewing configuration. When using the star diagonal, the image is right-side-up, but reversed from left-to-right. If inserting the eyepiece into the accessory adapter (i. e. , without the star diagonal), the image is inverted (upside down and reversed from left-to-right). This holds true for the 9x50 finder as well as the telescope. For correct orientation through the telescope, which is important primarily for terrestrial observing, use the optional 45° erect image diagonal 1-1/4" (#94112-A). Actual image orientation as seen with the unaided eye Reversed from left to right, as viewed with a Star Diagonal Figure 4-2 Inverted image, as viewed with the eyepiece directly in telescope 29 Focusing To focus your telescope, simply turn the focus knob located directly below the focuser. 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. Although this is the maximum useful magnification, most observing is done in the range of 20 to 35 power for every inch of aperture which is 120 to 210 times for the C60-E telescope. Determining Field of View Determining the field of view is important if you want to get an idea of the angular size of the object you are observing. To calculate the actual field of view, divide the apparent field of the eyepiece (supplied by the eyepiece manufacturer) by the magnification. In equation format, the formula looks like this: Apparent Field of Eyepiece True Field = Magnification As you can see, before determining the field of view, you must calculate the magnification. Using the example in the previous section, we can determine the field of view using the same 20mm eyepiece. The 20mm eyepiece has an apparent field of view of 50°. Divide the 50° by the magnification, which is 60 power. This yields an actual field of . 83°, or nearly a full degree. To convert degrees to feet at 1, 000 yards, which is more useful for terrestrial observing, simply multiply by 52. 5. Continuing with our example, multiply the angular field . 83° by 52. 5. This produces a linear field width of 43. 6 feet at a distance of one thousand yards. The apparent field of each eyepiece that Celestron manufactures is found in the Celestron Accessory Catalog (#93685). General Observing Hints When working with any optical instrument, there are a few things to remember to ensure you get the best possible image. · · · · Never look through window glass. [. . . ] Azm Set Position: 80, 3, 16, 4, PosHigh, PosMed, PosLow, 0 b. Alt Set Position: 80, 3, 17, 4, PosHigh, PosMed, PosLow, 0 59 APPENDIX E ­ MAPS OF TIME ZONES 60 61 62 63 64 65 66 3 67 CELESTRON TWO YEAR WARRANTY A. Celestron warrants this telescope to be free from defects in materials and workmanship for two years. Celestron will repair or replace such product or part thereof which, upon inspection by Celestron, is found to be defective in materials or workmanship. [. . . ]