Orion 7338 Getting Started, Optical Use, Use of 2 Eyepieces and Diagonals, Using as a Guidescope

Models: 7338

1 4
Download 4 pages 18.15 Kb
Page 2
Image 2
Getting Started

Congratulations on your purchase of an Orion Deluxe 100mm f/6 optical tube. Your telescope has been designed with high quality precision optics and excellent mechanical construction. The linear bearing dual-speed (10:1) Crayford focuser will make getting sharp images a breeze and reduce image shift to almost zero. The intermediate f/6 focal ratio will show only moderate color fringing. Your new telescope is versatile enough to also be used as a guidescope. These instructions will help you set up and use your optical tube.

Getting Started

The Deluxe 100mm f/6 comes fully assembled from the fac- tory. The telescope’s optics have been assembled and col- limated at the factory, so you should not have to make any adjustments to them.

Please keep the original shipping box. In the unlikely event you need to ship the telescope back to Orion for warranty repair service, you should use the original packaging. The box also makes a very good container for storing the telescope when it is not in use.

Optical Use

The fine optics and precision machining make the Deluxe 100mm f/6 an excellent choice for astronomical and terres- trial observation. You will need to add an optional diagonal and eyepiece to the back end of the telescope. The telescope will accept 2" or 1.25" accessories. Simply slide your diagonal into the open end of the telescope and insert the eyepiece into the diagonal and it is ready to show you the visual beauty of the night sky.

For terrestrial observation a correct image diagonal is recom- mended. These are typically available as 1.25" accessories only.

Use of Optional Eyepieces, Diagonal, and Finder Scope

The Deluxe 100mm f/6 does not come with a finder scope, diagonal or eyepieces in order to grant the user the greatest versatility in customizing the instrument to suit their needs. However, certain rules for using accessories still apply.

Any Orion finder scope with a dovetail bracket can be used with the Deluxe 100mm f/6. Simply unthread the thumbscrew on the dovetail mount and insert the assembled finder scope and dovetail bracket. Retighten the thumbscrew (Figure 1). Finder scopes that do not use a dovetail bracket will need to be attached by other means.

The Deluxe 100mm f/6 can use 1.25" accessories. Please note that the telescope will not come to focus without the use of a diagonal or extension tube. To install a diagonal, unthread the thumbscrew on the 1.25" adapter until it is flush with the interior of the adapter (Figure 1). Insert the diagonal or exten-

sion tube and secure it with the thumbscrew. Then insert the eyepiece into the diagonal or extension tube and secure it with the thumbscrew(s).

Use of 2" Eyepieces and Diagonals

A feature of the Deluxe 100mm f/6 is its ability to also use 2" barrel-diameter eyepieces and diagonals. At low magnifica- tions, 2" eyepieces can give a wider field of view than stan- dard 1.25" eyepieces. This is especially desirable for observ- ing deep-sky objects, as many of them appear quite large, but faint.

To use 2" eyepieces, simply loosen the large thumbscrew on the 2" adapter (Figure 1). Once this thumbscrew is loosened, the entire back end of the focuser, including any 1.25" diago- nal and eyepiece that may be attached, comes off, exposing the 2" adapter. Now, insert your 2" diagonal into the drawtube and secure with the thumbscrew loosened previously. Insert a 2" eyepiece into the diagonal, secure it in place with the thumbscrew on the diagonal, and you’re ready to observe.

About the 2" Linear Bearing Dual-Speed Crayford Focuser

The Deluxe 100mm f/6 comes equipped with a 2" linear bear- ing dual-speed Crayford focuser. The linear bearing Crayford design allows for smooth, precise focusing without the image shift that rack-and-pinion and typical Crayford designs experi- ence. The linear bearing is a “track” that guides the drawtube in and out on a precise path to further reduce any wobble in the drawtube which could cause image shift.

There is also a fine adjustment capability on this focuser. Ten turns of the small knob protruding from the right focus knob equals one turn of the coarse adjustment knob. Once you have achieved the best possible focus on an object using the coarse adjustment knob; you can fine-tune your focus using this slow motion knob to make micro-adjustments. This will allow delicate adjustments to be made to get the sharpest images possible.

If you find that the focus adjustment is too hard to turn or does not hold in place properly once you’ve achieved focus, you can make adjustments to the focuser tension by using the focus tension thumbscrew located on the bottom of the opti- cal tube, between the focus knobs. Make adjustments to this thumbscrew until the focuser motion feels smooth to turn and holds in place when you have obtained focus. It may be nec- essary to make adjustments when the weight of your acces- sories change significantly.

Using as a Guidescope

The purpose of the guidescope is to monitor a guide star dur- ing long-exposure astrophotography in order to make correc- tions to the mount’s tracking rate. This is done by centering a star on the reticle of the illuminated reticle eyepiece used with the guidescope. By keeping that star centered you assure that the view through the telescope (and imager) remains constant. Without use of a guidescope, the telescope will not

2

Page 2
Image 2
Orion 7338 instruction manual Getting Started, Optical Use, Use of 2 Eyepieces and Diagonals, Using as a Guidescope