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1. Keeping Your Telescope Clean
|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. |
Prevention is the best recommendation that a telescope owner can follow in keeping astronomical equipment in top
working order. Proper measures taken during observations and when storing the equipment between observation
runs can add many years of trouble free use.
Dust and moisture are the two main enemies to your instrument. When observing it is advisable to always use a
proper fitting Dew Shield (such as the Meade #710, or #712). The Dew Shield not only prevents dew from forming,
and dust from settling on the corrector plate lens, it prevents stray light from reducing image contrast.
Although dew shields go a long way to prevent moisture build-up, there can be times when the telescope optics will
have a uniform coating of moist dew. This is not particularly harmful, as long as the instrument is allowed to let the
dew evaporate. This can be done with a hair dryer, or just setting up the telescope indoors with the dust covers
removed. It is also advisable that you let the optional foam lined case for the LX200 dry out indoors for a day if the night was
moist. Packing your telescope away in a moist case can result in giving it a steam bath later. Anytime the LX200 is
being stored or transported, be sure to release the R.A. and Dec. Locks, to prevent serious damage to the drive
Never attempt to wipe down optics that are covered with dew. Dust and dirt may be trapped with the collected
dew, and upon wiping the optics you may scratch them. After the dew has evaporated you will most likely find
them in fine condition for the next observing session.
If you live in a very moist climate, you may find it necessary to use silica dessicant stored with the telescope to
ward off moisture and the possibility of fungus growing on and within the coatings of the optics. Replace the silica
dessicant as often as necessary.
Those living in coastal areas or tropic zones should also cover the electronic ports on the Power Panel and the
Keypad with gaffers tape to reduce corrosion on the metal contacts. Apply a dab of a water displacement solution
(such as WD-40) with a small brush on all of the interior metal contacts and the input cord metal contacts. The Keypad
and all separate accessories should be kept in sealable plastic bags with silica dessicant.
A thick layer of dust will attract and absorb moisture on all exposed surfaces. Left unattended, it can cause damaging
corrosion. To keep dust at bay when observing, the telescope can be set up on a small section of indoor/ outdoor
carpet. If you are observing for more than one night in a row, the telescope can be left set up but covered with a large
plastic bag (such as the one supplied with the telescope). The rear cell opening of the LX200 can also be sealed off to
the elements by threading on the optional accessory Skylight 1 A Dust Seal*. Eyepieces, diagonals, and other
accessories are best kept in plastic bags and stored in cases, such as the Meade #50 Accessory case*.
All of the non optical surfaces of the LX200 should be cleaned routinely with a soft rag and alcohol to prevent
corrosion. The cast metal surfaces and the individual exposed screws can also be kept looking new and corrosion
free by wiping them down with a water displacement solution (such as WD-40). Take care not to smear the solution
onto any optical surface, and to wipe up any excess solution with a clean dry cloth. The painted tube can be polished
with a liquid car polish and a soft rag.
Surprisingly, the most common telescope maintenance error is cleaning the optics too often. A little dust on any of the
optical surfaces causes virtually zero degradation of optical performance. It should be of no concern whatsoever to
see some small particles on the inside or outside of telescope optics. Should the optics get more dust on them than
you would care for, simply use a photographic grade camel hair brush with very gentle strokes. You can also blow off
dust with an ear syringe (available from a local pharmacy).
There is a point, however, when the optics must be cleaned. This is when you can easily tell that there is a thin layer of
fine particulates that make the optics look very slightly hazy. To clean the optics we must suggest that you make your
own lens cleaning solutions, since it is impossible to know all of the ingredients used in commercial lens cleaners.
Pure isopropyl alcohol (90% or better) will clean most residual film buildup on optical surfaces (and metal surfaces
For removing saliva marks, grease, fingerprints, or most any oily residue, the following recipe is advised: 1 part pure
isopropyl alcohol, 2 parts distilled water, and 1 drop of biodegradable liquid dishwashing soap per pint of solution.
This formula is safe for multi-coated, or even non-coated optical surfaces. Sprayer bottles make for convenient
dispensing of the lens cleaning solutions.
It is advised that you avoid many of the so-called lens cleaning papers (many which contain fiberglass), lens cloths, or
chamois. Use a white "Kleenex"-type tissue. The tissue can be formed into smooth pillow surfaces. Make several of
these before starting the cleaning process. If the optics are small (such as viewfinders or eyepieces), the tissue can
be rolled to the appropriate thickness and then broken in half to create two cleaning wands.
Before attempting to clean an optical surface with a liquid solution, it is very important that as much dust as possible is
removed by using forced air and/ or gentle strokes with a photographic grade camel hair brush. The forced air can
come from a rubber ear syringe, or canned compressed air from a photographic supply store. Be sure to hold the
canned air in a vertical position and try spraying compressed air on your hand before aiming at the optics to see if any
of the propellant (solid material) comes out. Propellant is very difficult to remove from optics, so take care not to tip the
can when using it. If you have access to a compressor hose, be sure that it is filtered to prevent oil from being sprayed
on the optics.
Once you are confident that you have removed most of the dust and large particles, begin cleaning with the pure
isopropyl. Pour or spray enough solution onto a pillow or wand of tissue until it is quite wet. If you are cleaning a
corrector plate, use radial strokes with a smooth pillow of tissue, starting from the center out using no pressure. If you
are cleaning small optical surfaces, use the rolled wands of tissue starting from the edges then spiraling in to the
center, again using no pressure. Never pour or spray the solution onto the corrector plate or eyepieces themselves, as
the liquid may go behind or in between lenses, where it is difficult or impossible to reach. Never attempt to
disassemble an eyepiece to clean the inner elements, as you will certainly not be able to properly center and
re-assemble the optical train.
Use dry tissue to make the final clean up, again using no pressure. If there is still some sort of residue, use the the
three part formula described above, again using the same cleaning techniques.
The inside surface of the corrector plate and secondary mirror may at some point become dirty due to particles falling
inside the tube when removing or replacing the rear dust cover or threading on accessories. To reduce the chance of
interior contamination, the Meade Skylight 1 A Dust Seal is very effective. If the Dust Seal is not used, it helps to have
the rear cell pointed downward when replacing the rear dust cover or attaching accessories.
Another more serious, but not damaging problem is the possibility of a hazy (usually uneven) film building up on the
inside of the corrector plate. This can be caused by environmental pollutants, or temperature changes reacting with
the interior paint, causing outgassing or water condensation, or combinations thereof.
It is possible to clean the interior of the optical system yourself or to have it done professionally. In the case of the
former, take great care in handling the optics. Any impact or rough handling can damage the surfaces, which may
require complete optical replacement at Meade Instruments at substantial cost. Meade Instruments assumes no
liability for damage incurred to the telescope by the customer.
The cleaning techniques described above are used while cleaning the interior of the optical system, with one
exception: Do not apply cleaning solutions to the front surface mirrored optics. Only use the soft camel hair brush
and the suggested ear syringe for removing particles. The corrector plate can be cleaned in the normal manner. To
remove the corrector plate, follow the instructions below:
- Remove the six (for 8" and 12" models) or the eight (for 10" models) stainless steel screws that hold the plastic
corrector plate retaining ring with the raised white lettering in place. This should be done with the Drive Base
placed flat on a work bench, and the optical tube assembly pointed up at a 45 degree angle with the declination
lock secure to prevent accidental dislodging of the corrector plate.
- Remove the plastic retaining ring and locate the two white alignment marks, one at the edge of the corrector plate
lens and one beside it on the black metal front cell. These two marks line up and serve as the precise rotational
position of the corrector plate in the optical train. If no marks exist, make two yourself with a small paintbrush and
some white paint, so that when you return the corrector plate to the front cell you are putting it back on the same
way that you took it off.
- Remove the corrector plate from the telescope, holding it by the plastic central secondary housing. Flip it over so
that the secondary mirror is facing you, then reinsert the corrector plate back into the front cell. This will allow you
full access to clean the interior optical surfaces without touching them with your fingers.
- When cleaning is complete, replace the corrector plate in it's original position, carefully lining up the rotational
index marks. Then replace the plastic retainer. Partially thread in all of the stainless steel screws, then one at a
time snug the screws down to prevent the corrector plate from rotating in the front cell. Take care not to
overtighten the screws as it will stress the corrector plate lens.
- A final check of the optical system is to inspect for proper collimation (alignment) of the optics.
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2. Collimation (Alignment) of the Optical System
The optical collimation of any astronomical telescope used for serious purposes is important, but in cases of the
Schmidt-Cassegrain design of the LX200 8", 10", and 12", such collimation is absolutely essential for good
performance. Take special care to read and understand this section well so that your LX200 will give you the best
Note: The 7" Maksutov-Cassegrain LX200 does not require collimation.
For final optical tests, every Meade Schmidt-Cassegrain is precisely collimated at the factory before shipment. Our
company is well aware that through shipment and normal handling, the optical alignment can be lost. The design of
the optical support system make the method of collimation easy to do. Even the uninitiated can make an alignment of
the optics to the same high precision that is performed in the Meade Instruments Optical Laboratories.
Fig. 26: Coillimation of the Optical System (1), (2), (3) Set screws for adjusting collimation.
To check the collimation of your LX200, center a bright star that is overhead, or use a reflected "hot spot" of reflected
sunlight from a chrome car bumper or a telephone pole insulator, with the supplied 26mm eyepiece. To make a
correct evaluation of the alignment it helps if the telescope has been allowed to either cool down or warm up to the
temperature where the instrument is set up. 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 (the dark center of the ring is the shadow of the secondary mirror). Turn the focus knob until the ring of light fills
about 1/8th of the eyepiece field. Take note that if you keep cle-focusing the star past about 1/8th of a field, that the ring
will look perfectly concentric (even on all sides) even if the optics are out of alignment, preventing you from seeing any
misalignments. If the ring of light does not seem to be even on all sides, or if the dark center seems to be offset in the
in the ring of light, follow the method below:
To make collimation easy, the only adjustments possible on the 8", 10" or 12" LX200 come from the three set
screws (shown in Fig. 26) located at the edge of the outer surface of the secondary mirror housing.
DON'T FORCE THE 3 COLLIMATION SCREWS PAST THEIR NORMAL TRAVEL AND DO NOT LOOSEN THEM ]VIORE
THAN 2 FULL TURNS (COUNTER CLOCKWISE DIRECTION), OR THE SECONDARY MIRROR MAY COME LOOSE FROM
IT'S SUPPORT. YOU WILL FIND THAT THE ADJUSTMENTS ARE VERY SENSITIVE: USUALLY, ONLY TURNING A
COLLIMATION SCREW 1/2 A TURN WILL GIVE DRAMATIC RESULTS.
Fig. 27: Defocused Star Images
While looking at the de-focused star image and noticing which direction the darker shadow is offset in the ring of
light or noticing which part of the ring is the thinnest (1, Fig. 27), 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 (or an assistant's 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 (or your assistant's) 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.
Using the telescope's slow motion controls, move the de-focused image to the edge of the eyepiece field of view
(2, Fig. 27), in the same direction as the darker shadow is offset in the ring of light.
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 out-of-focus 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 to the center of the
If while turning, you feel the screw get very loose, tighten the other two screws by even amounts. If while turning
the set screw gets too tight, unthread the other two by even amounts.
When you bring the image to center (3, Fig. 27), 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.
As a final check on alignment, examine the star image in-focus with the higher power eyepiece as suggested
above, under good seeing conditions (e.g. steady atmospheric conditions). The star point should appear as a
small central dot (the so-called "Airy disc") with a diffraction ring surrounding it. To give a final precision
collimation, make extremely slight adjustments of the 3 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 final step.
- You may find after your initial adjustment that the dark center is off in a new direction, e.g. instead of side to side
off, it is off in an up and down direction. If this is the case follow steps 2 through 6 as described above to find the
new adjustment screw.
- Now try a higher power (e.g. 9mm or less) eyepiece and repeat the above tests. Any lack of collimation at this
point will require only very slight adjustments of the 3 set screws. You now have a good collimation.
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3. Adjusting the Right Ascension Lock
After a period of time, it is possible that the R.A. lock (7, Fig. 3) of the LX200 will 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 hex wrenches supplied
with the telescope. Then, with a pair of pliers, tighten the shaft protruding outward from the drive base until you cannot
easily rotate the fork arm in R.A. (Take care in this operation not to damage the cosmetic finish of your LX200).
Replace the R.A. lock lever so that its handle points straight out from the cross-bar connecting the fork arm.
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4. Behind the Power Panel
The LX200 Power Panel houses the back-up replaceable battery (2, Fig. 28) for the clock and calendar and a
replaceable standard 1.0 amp slow blow fuse (1, Fig. 28). The long-life lithium battery (Panasonic CR2032 3 volt or
Duracell DL2032B) is stored behind the front panel of the Drive Base. The battery does have to be changed every few
years, and is done so by unthreading the four phillips-head screws that secure the Front Panel to the Drive Base.
Then with a thin flat-head screw driver, lift the small coin-size battery out of its' holder. The new battery simply slides in
place. See the illustration below:
The 1 amp slow blow fuse will sacrifice itself to protect the LX200 electronics in the event that the telescope is
prevented from completing a GO TO function (e.g. the tube runs into something that keeps it from slewing). The
illustration below shows the location of the fuse.
(1) Fuse (2) Battery
Fig. 28: Reverse Side of Power Panel
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5. Factory Servicing and Repairs
Meade LX200 7", 8", 10", and 12" models have been designed and manufactured for years of trouble-free
operation and repairs should rarely be necessary. If a problem does occur, first write or call our Customer
Service Department. Do not return the telescope until you have communicated with us in this way, since the
great majority of the problems can be handled without the return of the telescope to us. However, should the
occasion arise that the instrument requires factory servicing, a Meade Instruments Customer Service
Representative will issue a Return Goods Authorization (RGA) number and give you full instructions on how
to use it. Product returned without the RGA may greatly delay any servicing or repairs. When telephoning or
writing, please explain the exact nature of the problem so that we may offer a prompt remedial procedure.
Be sure to include your full name, address, phone and fax numbers where you can be reached.
Should you live outside of the United States, contact your Authorized Meade Distributor from where you
purchased the instrument.
You can reach the Meade Instruments Customer Service Department either by mail, phone, or fax at: Meade
Instruments Corporation, 6001 Oak Canyon, Irvine, CA 92620-4205, telephone (714) 451-1450, or telefax
(714) 451-1460. Outside of the U.S.A., dial your International Access Code, then 1, then the ten digit
number above in the 714 area code.