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2. Features and Functions
Your EON ED-X2 Triplet has premium features designed to
maximize the performance of the scope and its convenience of
use. Most notably, the air-spaced three-element objective lens
comprises two elements precision crafted from Japanese-
made Ohara extra-low dispersion ("ED") glass – one element
of FPL-53 and one element of FPL-51 fluoro-crown optical
glass – which together deliver true apochromatic performance,
eliminating chromatic aberration for impeccably clean, sharp,
high-resolution images.
Please refer to Figure 1 to become familiar with the tele-
scope's features.
Holes for finder
scope shoe
Draw tube
millimeter
scale
A.
B.
The top (A) and underside (B) of the hybrid drive
Figure 2.
dual-speed focuser (EON 104mm focuser shown).
Rotation lock thumbscrew
Focuser rotation interface
Rotation tensioning
setscrew (x3)
Coarse focus
knobs
Fine focus
(11:1) knob
Accessory collar
rotation interface
Rotation lock
thumbscrew
Rotation tensioning
setscrew (x3)
2" accessory collar
1.25" accessory collar
Focus lock knob
Drawtube tension
setscrew
Retractable Dew shield
The dew shield of the EON 85mm and 104mm is retractable,
allowing the telescope to become more compact for storage.
To extend the dew shield, simply pull it forward until it stops.
There is no thumbscrew to loosen or tighten. Extend the dew
shield while observing or imaging to block extraneous light and
to forestall the formation of dew on the exposed surface of the
objective lens.
Dual-speed Hybrid-Drive Focuser
Both the EON 85mm and EON 104mm ED-X2 telescopes fea-
ture a patented hybrid drive rack-and-pinion focuser. Its diag-
onal gearing provides exceptionally smooth, backlash-free
focus motion and excellent rigidity for holding heavy imaging
trains—up to 17.6 lbs.—without flexure or slippage. The 2.7"
focuser of the EON 104 and the 2" focuser of the EON 85
ensure that even full-frame imaging sensors will have a gener-
ously large fully illuminated field.
The dual-speed (11:1) focusing mechanism will keep your tar-
get object crisp and sharp. For quick focusing, the two large
focus knobs provide a coarse focus. For more precise focus-
ing, as needed for applications such as high-power planetary
observing and imaging with a CCD or digital camera, the
smaller focus knob on the right side (Figure 2A) offers an
11:1 fine focus adjustment (~11 turns of the fine focus knob
equal 1 turn of the coarse focus knob). If you find that the focus
motion feels too stiff or if, on the contrary, the drawtube slips
easily under the weight of your eyepiece or camera, you can
make adjustments to the focuser tension with the drawtube
tension set screw located on the bottom side of the focuser
(Figure 2B). Use the included 2.5mm Allen wrench to adjust
it until the focuser motion feels smooth and the drawtube holds
in place under load when you have obtained focus. It may
be necessary to make adjustments when the weight of your
accessories changes significantly.
The 2" accessory collar on the focuser has a robust twist-lock
mechanism and an internal compression ring for securing a
diagonal, field flattener, camera adapter, or other 2" accesso-
ries. The twist-lock mechanism provides an extremely secure
attachment and obviates the need for thumbscrews, which can
sometimes fall out and get lost. Each scope also comes with a
2"-to-1.25" step down adapter, which has the same convenient
twist-lock mechanism and compression ring. This adapter is
required for 1.25" accessories.
The telescope must be used with either a diagonal or exten-
sion tube (both sold separately) in order for an eyepiece to
reach focus. In most cases, you will be using a 90° star diago-
nal for visual use with an eyepiece.
Engraved Millimeter scale
The drawtube of the EON's focuser features a laser-engraved
millimeter scale on top, which aids in providing repeatable
focus. When precise focus is achieved, noting the value on the
scale where the drawtube meets the focuser housing will allow
you to return to approximately the same point, such as when
focusing the same camera in subsequent imaging sessions.
Using the scale can save time compared to finding the focus-
ing point "from scratch." The EON 85mm and 104mm ED-X2
have 98mm and 96mm of drawtube travel, respectively.
3
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