Meade-instruments LXD 75-Series User Manual download pdf (Page 40)

MAINTENANCE

General Maintenance

LXD75-Series telescopes are precision optical instruments designed to yield a lifetime

of rewarding applications. Given the care and respect due any precision instrument,

your LXD75 will rarely, if ever, require factory servicing. Maintenance guidelines

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 LXD75 is used outdoors on a humid night, water condensation on the tele-

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,

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.

f. If your

LXD75 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.

g. Do not leave your

LXD75 inside a sealed car on a warm summer day; excessive

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

Note: It is not necessary

for the user to collimate the

refractor models.

SC-8 Schmidt-Cassegrain

users see ALIGNMENT OF

THE SCHMIDT-CASSEGRAIN

OPTICAL SYSTEM

, page 42.

Newtonian Reflector users

see ALIGNMENT OF THE

NEWTONIAN REFLECTOR

OPTICAL SYSTEM

, page 44.

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Meade-instruments LXD 75-Series User Manual Page 40

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