Orion ED80T CF User Manual

INSTRUCTION MANUAL

Orion® ED80T CF

Apochromatic Refractor

#9525

2" Diagonal

Dovetail base
for finder

Focuser rotation
lockscrew

Dew shield
(retracted)

2" Accessory
thumbscrew

Fine focus
knob

Course
focus
knob

Figure 1: The 80mm ED80T CF Apochromatic Refractor optical tube.

Focuser
rotation
lockscrew

1/4"-20
Mounting block

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IN 391 Rev. A 07/10

Congratulations on your purchase of an Orion
80mm f/6 Triplet Refractor. Your telescope has

been designed with high quality precision optics
and excellent mechanical construction. The dual­speed (11:1) Crayford focuser will make getting
sharp images a breeze and reduce image shift to
almost zero. The three element f/6 objective lens
offers excellent color correction. These instructions
will help you set up and use your optical tube.

Getting Started

The 80mm Triplet 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 80mm
Triplet an excellent choice for astronomical and terrestrial
observation. You will need to attach the 2" diagonal (included)
and optional eyepiece to the back end of the telescope. The
telescope will accept 2" or 1.25" accessories. Simply slide the
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 recom­mended. These are typically available as 1.25" accessories
only.

Use of Optional Eyepieces, Diagonal, and
Finder Scope

The 80mm Triplet does not come with a finder scope 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 80mm Triplet. 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 80mm Triplet can use 1.25" and 2" accessories. Please
note that the telescope will not come to focus without the use
of a diagonal or extension tube. To install a 1.25" diagonal,
unthread the thumbscrew on the 1.25" adapter until it is flush
with the interior of the adapter. Insert the diagonal or exten­sion tube and secure it with the thumbscrew. Then insert the
eyepiece into the diagonal or extension tube and secure it
with the thumbscrew(s).

Coarse

Focus lock
thumbscrew

Figure 2: Focuser detail

Use of 2" Eyepieces and Diagonals

A feature of the 80mm Triplet is its ability to also use 2" barrel­diameter 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" diameter focuser drawtube Now, insert your 2" diagonal
into the drawtube and secure with the two thumbscrews 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" Dual-Speed Crayford Focuser

The Triplet 80mm comes equipped with a 2" dual-speed
Crayford focuser. The Crayford design allows for smooth,
precise focusing without the image shift that rack-and-pinion
designs experience.

There is also a fine adjustment capability on this focuser.
Eleven 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 fo-

focus knob

11:1 fine
focus knob

2