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Congratulations on your purchase of an Orion
Ritchey-Chretien astrograph. These compact but
large-aperture telescopes are designed and opti-
mized for high-performance astrophotography
with CCD and DSLR cameras. Sporting an optical
design comprising hyperbolic primary and second-
ary mirrors, the RC is highly regarded by advanced
astrophotographers and professional observato-
ries worldwide. Even the vaunted Hubble Space
Telescope is an RC! Orion RCs deliver exceptional
image quality and resolution with zero image shift,
minimal coma, a highly baffled steel tube for out-
standing contrast, and exclusive mounting options
for optional finder scopes and guide scopes. Any
one of these superb instruments, when paired with
a good mount, will take your imaging pursuits to a
whole new and very exciting level.
Parts List
1
Optical tube assembly
1
2" Extension ring
2
1" Extension rings
1
Battery holder (10" RC only)
1
Starry Night SE digital download coupon
WARning:
Never look directly at the Sun with
the naked eye or with a telescope – unless you
have a proper solar filter installed over the front of
the telescope! Otherwise, permanent, irreversible
eye damage may result.
Unpacking Your Telescope
Use care when unpacking the shipping carton. We recom-
mend keeping the boxes and all original packaging materi-
als. In the event that the telescope needs to be shipped to
another location, or returned for warranty repair, having the
proper packaging will ensure that your telescope will survive
the journey intact. Returns for refund or exchange will not be
accepted without all of the original packaging. Once all items
have been removed from the box take a moment to confirm
that all pieces are present and intact. Refer to the Parts List to
aid in identifying the included items.
The Focuser
All Orion Ritchey-Chretien telescopes come standard with
a machined, all-aluminum, dual-speed focuser. The 6" RC
features a 2" Crayford focuser equipped with a removable
1.25" adapter (
Figure 1A). The 8" RC has a 2" linear-bearing
Crayford focuser, which has a stabilizing track on the under-
side of the drawtube that provides extra rigidity for carrying
heavy payloads (
Figure 2). Drawtube flexure is virtually elimi-
nated by stabilizing the drawtube within the focuser housing.
The 10" RC also boasts a linear bearing focuser, but with an
oversized housing and a larger 3.3" drawtube that terminates
in a 2" accessory collar.
The focuser on all three RCs has a 10:1 fine focus adjust-
ment. Every 10 turns of the small knob equals a single turn of
the large knob, to enable the micro-adjustment necessary for
the sharpest images possible. Use the coarse focus knob to
adjust the telescope until your object is as close to focus as
possible, then make fine adjustments with the black outside
knob.
Each focuser is also equipped with both a tension adjustment
knob for the drawtube and a drawtube locking knob. On the 6"
RC both knobs are on the underside of the focuser (
Figure
1B), whereas on the 8" and 10" models the tension adjust-
ment knob is on the underside of the focuser while the larger
locking knob is on top (
Figure 2). We recommend keeping
the tension adjustment knob fairly tight at all times as this will
minimize drawtube flexure and slippage.
The focuser can be rotated to a desired angle prior to final
focusing for astrophotographic framing by slightly loosening
the focuser attachment collar (turning it counterclockwise),
then rotating the focuser to the desired position, then retight-
ening the collar.
