Celestron CR-150 HD instruction manual Focusing, Attaching the Finder, Telescope Basics

Models: CR-150 HD

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Focusing

Focusing

Attaching the Finder

To focus your telescope, simply turn either of the focus knobs located under the focus tube(seefigure4-1). Turnthefocusknobsuntiltheimageissharp. Oncesharp,turnthe knobs toward you to focus on an object that is closer than the one you are currently observing. Turntheknobsawayfromyoutofocusonamoredistantobjectthantheone you are currently observing.

Whenworkingwithanyopticalinstrument,thereareafewthingstoremembertoensure you get the best possible image.

Never look through window glass. Glass found in household windows is optically imperfect, and as a result, may vary in thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your telescope. In most cases youwillnotbeabletoachieveatrulysharpimage,whileinsomecases,youmayactually see a double image.

Never look across or over objects that are producing heat waves. This includes asphalt parking lots on hot summer days or building rooftops.

Hazyskies,fog,andmistcanalsomakeitdifficulttofocuswhenviewingterrestrially. The amountofdetailseenundertheseconditionsisgreatlyreduced. Also,whenphotograph- ingundertheseconditions,theprocessedfilmmaycomeoutalittlegrainierthannormal withlowercontrastandunderexposed.

Ifyouwearcorrectivelenses(specificallyglasses),youmaywanttoremovethemwhen observing with an eyepiece attached to the telescope. When using a camera, however, you should always wear corrective lenses to ensure the sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times.

The finder is mounted in the bracket and only needs to be attached to the telescope. On the back of the telescope tube, just above the focusing knobs, there is a small bracket with a regular head screw in it. This is where the finder bracket is mounted. To install the finderscope:

1.Locate the mounting bracket near the back of the telescope tube.

2.Loosen the regular head screw from the mounting bracket on the telescope.

3.Slide the finder bracket onto the bracket on the telescope. The finder bracket will slide in from the back. Orient the finder so that the objective lens is toward the objective end of the telescope.

4.Tighten the regular head screw on the bracket to hold the finder in place.

22 • Telescope Basics

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Celestron CR-150 HD instruction manual Focusing, Attaching the Finder, Telescope Basics