Maintenance for the Meade ETX Line of Telescopes

Note: These care instructions were written with the ETX-90EC in mind, but they work perfectly well for any Meade ETX-model telescope.

The ETX-90EC is a precision optical instrument designed to yield a lifetime of rewarding applications. Given the care and respect to any precision instrument, the ETX-90EC will rarely, if ever, require factory servicing or maintenance.

How to Clean Meade ETX Telescopes

  • 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.
  • 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.
  • 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. A single drop of biodegradable dishwashing soap may be added per pint of solution. Use soft, white facial tissues and make short, gentle strokes. Change tissues often.
  • CAUTION: Do not use scented, colored, or lotioned tissues as damage to the optics could result.
  • In the very rare situation where cleaning the inside surface of the corrector lens becomes necessary, unthread the lens cell located at the front of the main tube. The entire correcting lens and secondary mirror system is mounted in this cell. The lens cleaner solution described in step 3 may be used to clean the inside surface of the lens.
  • CAUTION: Do not touch the aluminized circular surface of the secondary mirror with a finger, a tissue, or any other object. Scratching of the mirror surface will almost certainly result.
  • NOTE: When cleaning the inside surface of the correcting lens, leave the lens mounted in its metal cell throughout the process. Do not remove the lens from its metal housing or else optical alignment of the lens will be lost, necessitating a return of the telescope to the Meade factory.
      • If the ETX-90EC is used outdoors on a humid night, telescope surfaces may accumulate water condensation. 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 being packed away. Do not, however, wipe any of the optical surfaces. Rather, simply allow the telescope to sit for some time in warm indoor air, so that the wet optical surfaces can dry unattended. In addition, the dust cap should not be placed back on to the optical tube until the telescope is thoroughly dry.
      • If the ETX-90EC is not to be used for an extended period, perhaps for one month or more, it is advisable to remove the eight AA-size batteries from inside the drive base. Batteries left installed for prolonged periods may leak, causing damage to the telescope's electronic circuitry
      • The super-gloss anodized finish of the ETX-90EC's deep-violet optical tube fades if left in direct sunlight for prolonged periods.
      • Do not leave the ETX-90EC telescope outdoors on a warm day or inside a sealed car for an extended period of time; excessive ambient temperatures can damage the telescope's internal lubrication and electronic circuitry.
      • A set of two (English-format) hex wrenches is provided with each ETX-90EC Astro Telescope. These wrenches are used as follows:
        • Small wrench (.05"): Use the small wrench to tighten the set-screws of any knobs which may loosen (e.g., the focus knob or flip-mirror control knob).
        • Medium wrench (1/16"): This wrench is used to detach the viewfinder bracket from the telescope's rear-cell.

      If you feel uncomfortable cleaning your own telescope, OPT is here to help. We have a factory-trained telescope technician on our staff that can clean, collimate, or (if necessary) repair your ETX. Call us for pricing and details.

      How to Store and TransportMeade ETX Telescopes

      When not in use, store the telescope in a cool, dry place. Do not expose the instrument to excessive heat or moisture. It is best to store the telescope in its original box with the vertical and horizontal locks (6 and 10, Fig. 1 in your manual) in the unlocked positions. If shipping the telescope, use the original box and packing material to protect the telescope during shipment.

      When transporting the telescope, take care not to bump or drop the instrument; this type of abuse can damage the optical tube and/or the objective lens. It is highly recommended to use a carry case when transporting the telescope.

      2 Responses

      Theodore E Wiersema

      March 07, 2023

      I have a Meade ETX Astro Telescope Model M … it was recently given to me after having rarely been used. I cannot get sharp focus on any daytime image or night image. I have cleaned… tried different lenses and googled everything. I think it needs to be collimated. Do you provide that service? If so, what is the price…and am I better just junking it and buying new?

      David Fisher

      September 13, 2022

      I have a mead d 90 mm f1000 mm telescope I’ve had for probably 30 years the inside lens has mold or dirt on inside is there any way I can clean the inside by taking the optical lens apart if not would it be worth sending it off and having it cleaned and repaired thank you very much.

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