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8" LX10 Schmidt-Cassegrain Telescope Instruction Manual
 D. TELESCOPE TROUBLESHOOTING, MAINTENANCE AND SERVICING
IMPORTANT NOTICE! Never use a telescope or spotting scope to look at the Sun! Observing the Sun, even for the shortest fraction of a second, will cause irreversible damage to your eye as well as physical damage to the telescope or spotting scope itself.
The 8" LX10 Schmidt-Cassegrain Telescope is a precision optical instrument designed to yield a lifetime of rewarding applications. Given the care and respect due any precision instrument, the LX10 will rarely, if ever, require factory servicing. Maintenance guidelines include:

  1. 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.

  2. When absolutely necessary, dust on the front lens should be removed with very gentle strokes of a camel's hair brush or blown off with an ear syringe (available at any pharmacy).

  3. Organic materials (e.g., fingerprints) on the front lens may be removed with a photographic lens cleaner solution, using soft, white facial tissues. Make short, gentle strokes and change the tissues often.

  4. 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.

  5. If the LX10 is used outdoors on a humid night, water condensation on the telescope 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.

  6. If the LX10 is not to be used for an extended period, perhaps for one month or more, it is advisable to remove the batteries from inside the control panel. Batteries left in the power panel for prolonged periods may leak, causing damage to the telescope's electronic circuitry.

  7. Do not leave the LX10 inside a sealed car on a warm summer day; excessive ambient temperatures can damage the telescope's internal lubrication and electronic circuitry.

  8. A set of four hex wrenches is provided with the LX10 in the following sizes: 1/16", 5/64", 3/32", and 5/32."

[ toc ] Collimation (Alignment) of the Optical System

The optical collimation of any astronomical telescope used for serious purposes is important, but in the case of the Schmidt-Cassegrain design of the 8" LX10, such collimation is absolutely essential for good performance. Take special care to read and understand this section well so that your LX10 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 LX10, center a bright star that is overhead with the supplied 25mm 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 central spot; the dark central spot is in fact the shadow of the secondary mirror. Turn the focus knob until the ring of light fills about 10% of the eyepiece field-diameter. If the dark central spot is offset in (i.e., not concentric with) the ring of light, your telescope's optical system is misaligned and requires collimation.

Follow these steps for collimation of the optical system:

  1. The only adjustments possible, or necessary, on the LX10 are from the three set screws (Fig. 21) located at the edge of the outer surface of the secondary mirror housing.

    Caution: Do not force the three collimation screws past their normal travel and do not loosen them more than two full turns in a counterclockwise direction or the secondary mirror may come loose from its support. You will find that the adjustments are very sensitive, usually requiring only one-half turn or less to produce the desired result.

    Figure 22

  2. While looking at the defocused star image, notice which direction the darker shadow is offset in the ring of light or notice which part of the ring is the thinnest (1, Fig. 22). Place your index finger in front of the telescope so that it touches one of the collimation set screws. You will see the shadow of your finger in the ring of light. Move your finger around the edge of the black plastic secondary mirror support until you see the shadow of the finger crossing the thinnest part of the ring of light. At this point, look at the front of the telescope where your finger is aiming. It will either be pointing directly at a set screw, or it will be between two set screws aiming at the set screw on the far side of the black plastic secondary mirror support. This is the set screw that you will adjust.

  3. Using the slow-motion controls, move the defocused image to the edge of the eyepiece field of view (2, Fig. 22), in the same direction as the darker shadow is offset in the ring of light.

  4. Turn the set screw that you found with the pointing exercise while looking in the eyepiece. You will notice that the star image will move across the field. If while turning the defocused star image flies out of the eyepiece field, then you are turning the screw the wrong way. Turn the opposite direction and bring the image back to the center of the field.

  5. If the screw you are turning becomes very loose, tighten the other two screws by even amounts. If the screw you are turning gets too tight, unthread the other two by even amounts.

  6. When you bring the image to center (3, Fig. 22), carefully examine the evenness of the ring of light (concentricity). If you find that the dark center is still off in the same direction, continue to make the adjustment in the original turning direction. If it is now off in the opposite direction, you have turned too far and you need to turn in the opposite direction. Always double check the image in the center of the field of the eyepiece.

  7. You may find after your initial adjustment that the dark center is off in a new direction (e.g., instead of being off side-to-side it is now off in an up-and-down direction). In this case repeat steps 2 through 6 to find the new adjustment screw.

  8. Now try a higher power eyepiece (e.g., 9mm or less) and repeat the above tests. Any lack of collimation at this point will require only very slight adjustments of the three set screws. You now have good collimation of the optics.

  9. As a final check on alignment, examine the star image in focus with the higher power eyepiece as suggested above, under good viewing conditions. The star point should appear as a small central dot (commonly referred to as an "Airy disc") with a diffraction ring surrounding it. To give a final precision collimation, make extremely slight adjustments of the three set screws, if necessary, to center the Airy disc in the diffraction ring. You now have the best alignment of the optics possible with this telescope.



[ toc ] Inspecting the Optics: A Note about the "Flashlight" Test

If a flashlight or other high-intensity light source is pointed down the main telescope tube, you may at first be shocked at the appearance of the optics. To the uninitiated, the view (depending upon your line of sight and the angle of the light) may reveal what appears to be scratches, dark or bright spots, or just generally uneven coatings, giving the appearance of poor quality optics.

These effects are only seen when a high intensity light is transmitted through lenses or reflected off the mirrors, and can be seen on any high quality optical system, including giant research telescopes.

The optical quality of a telescope cannot be judged by the "flashlight" test; the true test of optical quality can only be conducted through careful star testing.



[ toc ] Adjusting the Right Ascension Lock

After a period of time, the R.A. lock (3, Fig. 8) may not tighten sufficiently due to internal wear of the clutch mechanism. In such an event remove the R.A. lock lever using one of the supplied hex wrenches. Then, using a standard pair of pliers, tighten the shaft protruding outward from the drive base until you cannot easily rotate the fork arm in R.A., taking care not to scratch the finish of the telescope mounting. Replace the R.A. lock lever so that its handle points straight out from the crossbar connecting the fork arm.

[ toc ] Adjusting the Declination Lock

Continual use of the Declination lock (1, Fig. 9) may cause this lock to loosen. To retighten the lock, first turn the manual Declination slow-motion knob (2, Fig. 8) so that the Declination tangent arm (located inside the left-hand fork mount arm) is about in the middle of its travel. Put the Declination lock lever in the "unlocked" position (toward the eyepiece), and insert a 1/8" hex wrench into the notched-out section of the left-hand fork arm. Tighten the hex-head nut located just inside the notch.

Caution: In most instances only one turn of this hex-head nut is required to fully retighten the Declination lock.



[ toc ] Gauging the Movement of the Telescope

A common complaint of many first-time telescope owners is that they cannot see the telescope "move" when the motor drive is engaged. If fact, when the batteries are installed, the power is on and the R.A. lock engaged, the telescope is moving. However, the movement is at the same speed as the hour hand of a 24-hour clock; as such, the movement is difficult to discern visually.

To check the movement of your telescope, look at an astronomical object through the telescope's eyepiece with the telescope polar aligned and with the motor drive on. If the object remains stationary in the field of view, your telescope is operating properly. If not, check to ensure that you have engaged the R.A. lock and that the power switch on the control panel is on. If the telescope is still not tracking, replace the batteries.



[ toc ] Proper Storage and Transport of the LX10

When not in use, store your LX10 in a cool, dry place. Do not expose the instrument to excessive heat or moisture. In addition when the LX10 is to be stored for more than one month, remove the 4 AA-size batteries from the power panel; battery leakage may damage the telescope's electronic system.

When transporting the telescope, take care not to bump or drop the instrument; this type of abuse can cause the optical system to misalign or cause damage to the electronic components.



[ toc ] Contacting Meade Customer Service

If you have a question concerning your Meade 8" LX10 telescope, call Meade Instruments Customer Service Department at 949-451-1450, or contact us by fax at 949-451-1460. Customer Service hours are 8:30AM - 4:00PM, Pacific Standard Time, Monday through Friday.

In the unlikely event that your LX10 telescope requires factory servicing or repairs, write or call the Meade Customer Service Dept. first, before returning your telescope to the factory, giving full particulars as to the nature of the problem, as well as your name, address, and daytime telephone number. The great majority of LX10 servicing issues can be resolved by telephone, avoiding return of the telescope to the factory.

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