Meade LX90 instruction manual Maintenance, Collimation

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:

a.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 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 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 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 LX90, center a bright star that is overhead, or use a “hot spot” of reflected 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	(1)	(2)	(3)
central spot; the dark central spot is
in fact the shadow of the secondary
	Fig. 25: Defocused star images.
mirror. Turn the focus knob until the

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