Meade LNT Instruction Manual download pdf (Page 43)

MAINTENANCE

The LX90 is a precision optical instrument designed to yield a lifetime of rewarding applications.

Given the care and respect due any precision instrument, the LX90 will rarely, if ever, require

factory servicing. Maintenance guidelines include:

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

b. 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.

c. Organic materials (e.g., fingerprints) on the front lens may be removed with a solution of

3 par

ts 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 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.

e. If the LX90 is used outdoors on a humid night, water condensation on the telescope sur-

faces 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 the LX90 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 the LX90 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 8" LX90, such collimation

is absolutely essential for good performance. Take special care to read and understand this

section well so that your LX90 will give you the best optical performance.

As part of final optical testing, every Meade Schmidt-Cassegrain is precisely collimated at the

Meade f

actor

y bef

ore shipment.

, 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 LX90, center a bright star that is overhead, or use a “hot spot”

of reflected Sunlight from a chrome car b

umper

, with the supplied 26mm e

epiece

Allo

w the

telescope to adjust to the temper

ature of y

our obser

ation site bef

ore proceeding; temperature

diff

erences betw

een 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 f

ocus star image looks

lik

e a r

ing of light surrounding a dar

centr

al spot;

the dark central spot is

in fact the shadow of the secondary

mirror. Turn the focus knob until the

Fig.

25:

Def

ocused star images

(1) (2) (3)

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Meade LNT Instruction Manual Page 43

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