Meade LXD 75 instruction manual General Maintenance

Note: It is not necessary for the user to collimate the refractor models.

SC-8Schmidt-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.

MAINTENANCE

General Maintenance

LXD75-Seriestelescopes 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, 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 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

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