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Note: It is not necessary
for the user to collimate the
refractor models.
SC-8 Schmidt-Cassegrain
users see
ALIGNMENT OF
THE SCHMIDT-CASSEGRAIN
, page 42.
OPTICAL SYSTEM
Newtonian Reflector users
see
ALIGNMENT OF THE
NEWTONIAN REFLECTOR
, page 44.
OPTICAL SYSTEM
4 0
MAINTENANCE
General Maintenance
telescopes are precision optical instruments designed to yield a lifetime
LXD75-Series
of rewarding applications. Given the care and respect due any precision instrument,
your
will rarely, if ever, require factory servicing. Maintenance guidelines
LXD75
include:
a.
Avoid cleaning the telescope's optics: A little dust on the front surface of the tele-
scope's correcting lens causes virtually no degradation of image quality and
should not be considered reason to clean the lens.
b.
When absolutely necessary, dust on the front lens should be removed with gen-
tle strokes of a camel hair brush or blown off with an ear syringe (available at any
pharmacy). DO NOT use a commercial photographic lens cleaner.
c.
Organic materials (e.g., fingerprints) on the front lens may be removed with a
solution of 3 parts distilled water to 1 part isopropyl alcohol. You may also add 1
drop of biodegradable dishwashing soap per pint of solution. Use soft, white facial
tissues and make short, gentle strokes. Change tissues often.
Caution: Do not use scented or lotioned tissues or damage could result
to the optics.
d.
Do not, for any reason, remove the correcting plate from its machined hous-
ing for cleaning or other purposes. You will almost certainly not be able to
replace the corrector in its proper rotational orientation and serious degra-
dation of optical performance will result. Meade Instruments assumes no
liability for damage incurred to the telescope in this way.
e.
If the
is used outdoors on a humid night, water condensation on the tele-
LXD75
scope surfaces will probably result. While such condensation does not normally
cause any damage to the telescope, it is recommended that the entire telescope
be wiped down with a dry cloth before the telescope is packed away. Do not, how-
ever, wipe any of the optical surfaces. Rather, simply allow the telescope to sit for
some time in the warm indoor air, so that the wet optical surfaces can dry unat-
tended.
f.
If your
is not to be used for an extended period, perhaps for one month or
LXD75
more, it is advisable to remove the batteries from the telescope. Batteries left in
the telescope for prolonged periods may leak, causing damage to the telescope's
electronic circuitry.
g.
Do not leave your
LXD75
ambient temperatures can damage the telescope's internal lubrication and elec-
tronic circuitry.
Alignment (Collimation) of the Schmidt-Newtonian Optical
System
All Meade Schmidt-Newtonian telescopes are precisely collimated at the factory
before packing and shipment, and it is probable that you will not need to make any
optical adjustments before making observations. However, if the telescope sustained
rough handling in shipment, you may need to re-collimate the optical system. Such re-
collimation is not a difficult procedure in any case.
The collimation procedure for the Meade Schmidt-Newtonians is slightly different from
that of other Newtonian reflecting telescopes, because of the "fast" f/4 to f/5 focal ratio
of the primary mirror. In typical Newtonian reflectors with more conventional focal
ratios (i.e. longer focal ratios), when the observer looks down the focuser tube (with-
out an eyepiece in the focuser), the images of the diagonal mirror, primary mirror,
focuser tube, and the observer's eye appear centered relative to each other. However,
with the short focal ratio primary mirror of the Schmidt-Newtonian, correct collimation
requires that the diagonal mirror be offset in 2 directions: (1) away from the focuser
and (2) towards the primary mirror, in equal amounts. This offset is approximately 1/8"
in each direction. Note that these offsets have been performed at the factory prior to
inside a sealed car on a warm summer day; excessive
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