Orion 7338 User Manual

INSTRUCTION MANUAL

Orion® Deluxe 100mm f/6

Refractor

#7338

Dust cap

Dovetail base
for finder

Finder scope
lock knob

Dew shield
(retracted)

1/4"-20 Mounting block

Figure 1: The Deluxe 100mm f/6 refractor optical tube.

Focus knob

Focuser rotation
lockscrew

2" accessory
thumbscrew

1.25" accessory
thumbscrew

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IN 392 Rev. A 05/10

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 fac­tory. The telescope’s optics have been assembled and col­limated 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 terres­trial 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 inser t 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 recom­mended. 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 magnifica­tions, 2" eyepieces can give a wider field of view than stan­dard 1.25" eyepieces. This is especially desirable for observ­ing 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" diago­nal 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 bear­ing 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 experi­ence. 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 opti­cal 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 nec­essary to make adjustments when the weight of your acces­sories change significantly.

Using as a Guidescope

The purpose of the guidescope is to monitor a guide star dur­ing long-exposure astrophotography in order to make correc­tions 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

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