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7. If the ETX-LS is not to be used for an extended
period, perhaps for one month or 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.
8. Do not leave the ETX-LS inside a sealed car on
a warm summer day; excessive ambient
temperatures can damage the telescope’s
internal lubrication and electronic circuitry.
Collimation
The optical collimation (alignment) of any astronomical
telescope used for serious purposes is important,
but in the case of the Schmidt-Cassegrain design of
the ETX-LS, such collimation is absolutely essential
for good performance. Take special care to read and
understand this section well so that your ETX-LS will
give you the best optical performance.
As part of nal optical testing, every Meade Schmidt-
Cassegrain is precisely collimated at the Meade factory
before shipment. However, vibrations in shipping can
cause the optical system to become misaligned. Re-
aligning the optics is, however, a straightforward
process.
To check the collimation of your ETX-LS, center a bright
star that is overhead, or use a “hot spot” of reected
Sunlight from a chrome car bumper, with the supplied
26mm eyepiece. Allow the telescope to adjust to the
temperature of your observation site before proceeding;
temperature differences between the optics and the
outside air can cause distortion in the images.
With the star or hot spot centered, de-focus
the image.
You will notice that the out of focus star image looks
like a ring of light surrounding a dark central spot; the
The ETX-LS is a precision optical instrument designed
to yield a lifetime of rewarding viewing.
Given the care and respect due any precision
instrument, the ETX-LS will rarely, if ever, require
factory servicing. Maintenance guidelines include:
1. Avoid cleaning the telescope’s optics: a little dust
on the front surface of the telescope’s correcting
lens causes virtually no degradation of image
quality and should not be considered reason to
clean the lens.
2. When absolutely necessary, dust on the front lens
should be removed with gentle 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.
3. Organic materials (e.g., ngerprints) 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.
4. CAUTION: Do not use scented or lotioned tissues
that can damage the optics.
5. Do not, for any reason, remove the correcting
plate from its machined housing for cleaning
or other purposes. You will almost certainly
not be able to replace the corrector in its proper
rotational orientation and serious degradation
of optical performance will result. Meade
Instruments assumes no liability for damage
incurred to the telescope in this way.
6. If the ETX-LS is used outdoors on a humid
night, water condensation on the telescope
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, however, 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 unattended.
MAINTENANCE
(1) (2) (3)
Figure 8: Collimation
MAINTENANCE
33
INDEX