For high-magnification, high-resolution observation of terrestrial subjects,
the Meade ETX Spotting Scope is one of the finest telescopes ever
developed at any price. Explore the subtleties of a bird's feather structure
from 50 yards; read license plates more than one mile in the distance; or
use the ETX Spotting Scope for casual astronomical purposes.
Applications of the ETX are almost limitless.
|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. |
Note: "Spotting Scope" is a term used to define a telescope that is
primarily intended for terrestrial (land) viewing, as opposed to
astronomical applications. Notwithstanding this definition, the
ETX Spotting Scope, as is discussed below, can also be used
for casual astronomical observing. Similarly, the ETX Astro
Telescope, by definition an astronomical telescope, is often used
as a terrestrial instrument, as discussed in previous pages of this
manual. Astronomical telescopes, including the ETX Astro,
Telescope, normally include mounting systems and/or motor drives
specifically designed for astronomical objecttracking. Thus the
differences between a spotting scope and an astronomical telescope
generally lie not in the optical design but in the mechanical design
that makes it particularly suitable for its primary intended application.
Fig. 20: The ETX Spotting Scope
- Viewfinder Lens Cell
- Knurled Ring
- Front Alignment Screws
- Viewfinder Bracket
- Rear Alignment Screws
- 90° Eyepiece Holder
- Focus Know
- Knurled Ring of #932 45° Ericting Prism
- SP 26mm Eyepiece
- #932 45° Ericting Prism
- Flip-Mirror Control
- Tripod Adapter Block (1/4-20 thread)
- Photo Tripod (user-supplied)
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1. Parts Listing
When first opening the packing box of the ETX Spotting Scope,
note carefully the following parts included with the telescope:
- The ETX Spotting Scope optical tube assembly.
- 8 x 21 mm Viewfinder, packed in a separate, small box.
- Super PlössI (SP) 26mm eyepiece, packed in plastic storage container.
- #932 45° Erecting Prism
- Hex-wrench set with 2 (English-format) wrenches
The 8 x 21mm Viewfinder is packed separately from the main telescope
in shipment to avoid the possibility of the viewfinder slipping in its
bracket and scratching the viewfinder tube.
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2. Assembly Instructions
Assembly of the telescope requires only three quick steps:
NOTE: The viewfinder should be chocked for correct focus
prior to installation in the viewfinder bracket.
Assembly of the ETX Spotting Scope is now complete.
- Slide the viewfinder into its bracket (5, Fig. 20) with the
rubber-eyecup-end of the viewfinder fitting first through
the front end of the bracket. It may be necessary to
slightly unthread the six alignment screws (4 and 6, Fig.
20) to fit the viewfinder into the bracket. With the
viewfinder inside the bracket, tighten (to a firrn feel only)
the six alignment screws down against the viewfinder
tube. Alignment of the viewfinder is detailed on page 19.
- Remove the #932 45° Erecting Prism from its packing box.
After unthreading the Photo Port cover (6, Fig. 1) thread
the knurled ring (9, Fig. 20) of the #932 Prism on to the
Photo Port. "Firm feel" tightening is sufficient.
Note: The rear-cell thread of the ETX telescope is called
the "Photo Port," since this port is also used for
attachment of a 35mm camera body to the telescope
- Remove the SP 26mm eyepiece (10, Fig. 20) from its
plastic storage container and place it in the
eyepieceholder of the #932 Erecting Prism (11, Fig. 20)
tightening the eyepiece-holder's thumbscrew to a firm
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1. Quick Tips
- Viewfinder Alignment with Main Telescope: When
attached to the telescope, the viewfinder and main optical
tube are not aligned. Therefore, it is not possible to locate
objects in the main telescope using the viewfinder.
Procedures for aligning the viewfinder and main telescope
are detailed on page 19 of this manual.
- Flip-Mirror Orientation: Confirm that the Flip-Mirror
Control (12, Fig. 20) is in the "down" position so light is
directed to the eyepiece (see Telescope Controls,
- Focus Knob: Sharp focusing of a telescopic image
requires precise control of the focus knob (8, Fig. 20). Turn
the focus knob slowly for clear viewing of objects.
- A Note on Indoor Viewing: While casual, low-power
observations may be made with the telescope through an
open or closed window, the best observing is always done
outdoors. Temperature differences between inside and
outside air and/or the low quality of most home window
glass can cause blurred images through the telescope. Do
not expect high-resolution imaging under these conditions.
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2. Telescope Controls
Flip-Mirror Control (12, Fig. 20): The ETX includes an
internal optically-flat mirror. The Flip-Mirror Control is "down" when the
outer edge of the control is horizontal (parallel with the main
tube of the telescope. It is in the "up" position when the control
is vertical (perpendicular to the main telescope tube).
The Flip-Mirror Control must be in the "down" position in order
for light to reach the telescope's #932 Erecting Prism and
eyepiece. Images seen through the prism will appear correctly
oriented both up-and-down and left-to-right, just as they are
normally seen without a telescope.
Alternately, placing the Flip-Mirror Control in the "up" position
diverts incoming light to a right-angle and permits observations
with the eyepiece in the 900 eyepiece-holder (7, Fig. 20). If the
eyepiece is moved to this position, re-focusing is required,
and, while the image is correctly oriented up-and-down, it
appears reversed left-for-right. The 90° observing position is
particularly advantageous when observing objects high in the
sky, such as aircraft, or astronomical objects, such as the
Focus Knob (8, Fig. 20): Turning this knob causes a
finelycontrolled internal motion of the telescope's primary
mirror to achieve precise focus of the telescopic image. The
ETX can be focused on objects from a distance of about 11.5
ft (3.5m) to infinity. Rotate the focus knob clockwise to focus
on distant objects; rotate the focus knob counterclockwise to
focus on near objects.
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The magnification, or power, at which a telescope is operating
is determined by two factors: the focal length of the telescope
and the focal length of the eyepiece employed.
Telescope Focal Length: Generally speaking, telescope
focal length is the distance that light travels inside the
telescope before reaching a focus. In the mirror-lens design of
the ETX, however, this focal length is, in effect, compressed
by the telescope's secondary mirror, so that a long effective
telescope focal length is housed in the short ETX optical tube.
The ETX's focal length is 1250mm, or about 49". If the ETX
were a classical refracting-type of telescope, its optical tube
would thus be more than four feet long instead of the ETX's
compact 11" tube length.
Eyepiece Focal Length: The eyepiece focal length is the
distance light travels inside the eyepiece before reaching
focus. Focal length is usually printed on the side of the
eyepiece. The Meade ETX is supplied with one eyepiece as
standard equipment, a Super Plössl (SP) 26mm eyepiece.
Thus, the focal length of the provided eyepiece is 26mm.
"Super Plössl" refers to the optical design of the eyepiece, a
design specifically intended for high-performance telescopes
and one which yields a wide, comfortable field of view with
extremely high image resolution.
Technical note to the advanced amateur astronomer: The SP
26mm eyepiece supplied with Meade ETX telescopes is a
special low-profile version of the standard Meade SP 26mm
eyepiece and is about 114" (6mm) shorter than the standard
eyepiece. This low-profile SP 26mm is designed to harmonize
with the ultracompact scale of the ETX telescope and utilizes
the exact same optics as the standard SP 26mm eyepiece. The
SP 26mm low-profile eyepiece is not parfocal, however, with
other eyepieces in the SP series (i.e., the eyepiece requires
refocusing when it is interchanged with other SP eyepieces).
Calculating Magnification: On a given telescope, such as
the ETX, different eyepiece focal lengths are used to achieve
different magnifications, from low to high. The
standardequipment SP 26mm eyepiece, as stated above,
yields 48X. Optional eyepieces (see page 20) and the #126 2X
Barlow Lens are available for powers from 31X to over 300X.
To calculate the magnification obtained with a given eyepiece,
use this formula:
||Telescope Focal Length
|Eyepiece Focal Length
Example: The power obtained with the ETX with the SP 26mm eyepiece is:
The most common mistake of the beginning observer is to
"overpower" the telescope by using high magnifications which
the telescope's aperture and typical atmospheric conditions
can not reasonably support. Keep in mind that a smaller, but
bright and well-resolved, image is far superior to a larger, but
dim and poorly resolved, one. Powers above about 30OX
should be employed with the ETX only under the steadiest
Most observers will want to have 2 or 3 eyepieces to achieve
the full range of reasonable magnifications possible with the
ETX Spotting Scope.
The ETX Spotting Scope utilizes the exact same
astronomicalgrade optical system as its sister instrument, the
ETX Astro Telescope. As such, the ETX Spotting Scope may
theoretically be used for astronomical observations at powers
up to about 30OX, or slightly higher. However, such high
magnifications with the ETX Spotting Scope are impractical
because the telescope does not include either the fork
mounting system capable of polar alignment (see Polar
Alignment, page 8) or the automatic-tracking motor drive of
the ETX Astro Telescope (see The Motor Drive, page 10).
Astronomical objects located at high power with the ETX
Spotting Scope mounted on a photo tripod are also difficult to
track due to the same limitations.
At more moderate powers, however, such as between 31 X
and 63X, the ETX Spotting Scope can be used for observing
the Moon and planets, as well as some objects in deep-space.
Keep in mind that, notwithstanding the difficulty of tracking an
astronomical object with the ETX Spotting Scope, the optical
resolution of the image is identical to that of the ETX Astro
Telescope, since both instruments use identical optical
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The ETX Spotting Scope should be firmly attached to a suitable
photo-tripod, using the 1/4-20 tripod adapter block (13, Fig. 20)
located on the underside of the telescope's tube assembly.
Unthread the metal dust cap from the front lens. The ETX
Spotting Scope may now be used for observations, but be
sure to read at least the remainder of this section before
attempting to use the telescope. Keep in mind that the
viewfinder has not yet been aligned to the main telescope. As
a result, the observer must sight along the side of the main
tube to locate objects. With the standard-equipment SP 26mm
eyepiece mounted in the #932 450 Erecting Prism, as described
above, the telescope yields 48-power, written "48X."
Note: The dust cap should be replaced after each
Important Note: In the most discriminating applications,
such as in observing delicate bird feather-stnicture at
long distance, the ETXs intemal, optically-flat mirror
yields a higher-resolution image than is possible with
any prism, including the #932 45, Erecting Prism. In
these special cases ETX users are advised to observe
with the eyepiece in the 900 eyepiece-holder (17, Fig. 20)
with the Flip-Mirror Control in the "up" position. This
admonition applies only to situations requiring
extraordinarily high optical resolution and where the
observer's eye is welltrained to observe very fine detail.
In typical applications of the telescope terrestrially no
image differences between the two eyepiece locations
will generally be noted.
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1. The Viewfinder
The ETX Spotting Scope presents a fairly narrow field of view
to the observer. As a result it is sometimes difficult to locate
and center objects in the telescope's field of view. The viewfinder,
by contrast, is a low-power, wide-field sighting scope with
crosshairs that enable the easy centering of objects in the
main telescope's field. Standard equipment with the ETX
Spotting Scope is a viewfinder of 8-power and 21mm
aperture, called an "8 x 21 mm viewfinder."
Never use the Meade ETX 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
The ETX viewfinder, unlike most telescope viewfinders,
presents a correctly oriented image, both up-and-down and
left-to-right. This orientation particularly facilitates the location
of terrestrial objects. The 8 x 21mm viewfinder is also a
tremendous aid in locating faint astronomical objects before
their observation in the main telescope.
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a. Focusing the Viewfinder
The ETX viewfinder has been factory pre-focused to objects
located at infinity. Individual eye variations, however, may
require that the viewfinder be re-focused for your eye. Prior to
installing the viewfinder in the viewfinder bracket (5, Fig. 2),
check the focus by looking through the viewfinder. Point the
viewfinder at a distant object; if the viewfinder image is not
sufficiently in focus for your eye, it may be re-focused as
- Loosen the knurled lock-ring (2, Fig. 20 located near the
viewfinder's objective (front) lens (1, Fig. 20). Unthread
this ring (counterclockwise, as seen from the eyepiece-
end of the viewfinder) by several full turns.
- Focus the viewfinder by rotating the objective lens cell
(1, Fig. 20) in one direction or the other, until distant
objects observed through the viewfinder appear sharp.
One or two rotations of the viewfinder lens have a
significant effect on image focus.
- Once correct focus is reached, lock the focus in place by
threading the knurled lock-ring snugly clockwise up
against the viewfinder's lens cell.
- Place the viewfinder into the viewfinder bracket (5, Fig.
20) on the main telescope. Gently tighten the six
alignment screws (4 and 6, Fig. 20), then proceed with
alignment of the viewfinder.
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b. Alignment of the Viewfinder
In order for the viewfinder to be useful, it must first be aligned
with the main telescope, so that both the viewfinder and the
main telescope are pointing at precisely the same place. To
align the viewfinder follow this procedure:
- The viewfinder bracket (5, Fig. 20) includes six alignment
screws (4 and 6, Fig. 20). Turn the 3 rear-most
alignment screws (6, Fig. 20) so that the viewfinder tube
is roughly centered within the viewfinder bracket, as
viewed from the
eyepiece-end of the telescope.
Note: Do not overtighten the alignment screws. When
tightening one screw it may be necessary to loosen one
of the two other screws.
- Using the SP 26mm eyepiece, point the main telescope at
some easy-to-find, well-defined land object, such as the
top of a telephone pole. Center the object precisely in the
main telescope's field and engage the R.A. Lock and Dec
Lock so that the object can not move in the field.
- While looking through the viewfinder, turn one or more of
the 3 front-most viewfinder alignment screws (4, Fig.
20), until the crosshairs of the viewfinder point at
precisely the same position as the main telescope.
Re-check that the viewfinder's crosshairs and the main
telescope are now pointing at precisely the same object. The
viewfinder is now aligned to the main telescope. Unless the
alignment screws are disturbed, the viewfinder will remain
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c. Using the Viewfinder
To locate any object, terrestrial or astronomical, first center the
object in the crosshairs of the viewfinder; the object will then
also be centered in the field of the main telescope.
Note: If you intend to use higher observing magnifications,
first locate, center, and focus the object using a low-power
eyepiece (e.g., the SP 26mm eyepiece). Objects are easier to
locate and center at low powers; higher power eyepieces may
then be employed simply by changing eyepieces.
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2. Terrestrial Observing
Viewing terrestrial objects require observers to look along the
earth's surface through heat waves. These heat waves often
cause degradation of image quality. Low power eyepieces, like
the SP 26mm eyepiece provided with the ETX Astro Telescope,
magnify these heat waves less than higher powered
eyepieces. Therefore, low power eyepieces provide a
steadier, higher quality image. If the land image is fuzzy or ill-
defined, drop down to a lower power, where the earth's heat
waves will not have such a deleterious effect on image quality.
Observing in early morning hours, before the earth has built up
internal heat, is generally more advantageous than during late-
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3. Photography with the ETX Spotting Scope
Photography through the ETX Spotting Scope requires the
addition of the optional #64 T-Adapter (Fig. 21). With the #64 T-Adapter
attached to the telescope, through-the-telescope photography
is possible with any 35mm camera body with removable lens.
In this way the telescope effectively becomes the lens of the
For through-the-telescope photography, turn the Flip-Mirror
Control (1, Fig. 21) to the "down" position (see Telescope
Controls, page 18), allowing light to pass straight-th rough the
telescope and out the Photo Port (6, Fig. 1). With the Flip-Mirror
Control in the "down" position and the Photo Port's dust cover
removed, the front lens of the telescope can be seen when
looking through the Photo Port. The #64 T-Adapter threads on
to the Photo Port, followed by a T-Mount for the particular
brand of 35mm camera being used, followed in turn by the
camera body itself (with camera lens removed).
Fig. 21: Using the #64 T-Aclapter with the ETX Spotting Scope.
(1) Flip-Mirror Control in "down" position; (2) T-Mount; (3) Short
section of #64 T-Adapter; (4) Knurled ring.
Note that the #64 T-Adapter consists of two sections (1 and 2,
Fig. 11) which are threaded together in shipment. Either of the
following photographic mounting formats may be used to
couple the camera body to the telescope's Photo Port thread.
Format 1: Camera Body + T-Mount + Section (1) of the #64 T-Adapter.
Format 1 utilizes the short section only of the #64 T-Adapter
(3, Fig 21) to permit close-coupling of a camera body to the
telescope at an effective photographic speed of f/14 and a
transmission value (the so-called "T"-value) of 18. In this
format vignetting will occur: the photographic image will
appear on film as a circle, without illuminating the complete
Format 2: Camera Body + T-Mount + Sections (1) and (2) of
the #64 T-Adapter.
Format 2 utilizes both sections of the #64 T-Adapter threaded
together to form a rigid unit as shown in Fig. 11, the telescope
is operating at a photographic speed of f/16 and T-value of 23,
but without any field vignetting: images are illuminated to the
edges of a standard 35mm frame.
To frame an object in the viewfinder of the 35mm camera
body, loosen slightly the knurled ring (4, Fig. 21) which
threads the #64 T-Adapter to the telescope's Photo Port; rotate
the camera body to achieve proper framing of the object; then
re-tighten the knurled ring.
Photography through a long lens such as the ETX requires
special technique for good results, and the photographer
should probably expect to waste a roll or two of film in
acquiring this technique. Long-lens photography has its own
rewards, however; rewards that short-focus lenses can not
A few tips on photography through the ETX:
- Use a rigid, heavy-duty photo tripod as a platform for the
telescope. At effective focal lengths of 1250mm to
1450mm, even small external vibrations can easily ruin an
otherwise good photo.
- Use a cable-operated shutter release. Touching the
camera body to initiate shutter operation will almost
certainly introduce undesirable vibrations.
- Focus the image with extreme care. While observing the
subject through the camera's reflex viewfinder, turn the
ETX's focus knob (8, Fig. 20) to achieve the sharpest
- Correct shutter speeds vary widely, depending on lighting
conditions and the film used. Trial-and-error is the best
way to determine the proper shutter speed in any given
- Terrestrial photography through the ETX is sensitive to
heat waves rising from the earth's surface. Long
distance photography is best accomplished in the early
morning hours, before the earth has had time to build up
Note: Astronomical photography is not practical through the
ETX Spotting Scope, since the telescope is not mounted on a
motor driven astronomical (equatorial) mount Photos of the
Moon or planets taken with the ETX Spotting Scope mounted
on a photo tripod will appear blurred due to the earth's rotation
during the period of the exposure.
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TELESCOPE MAINTENANCE AND SERVICING
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1. General Maintenance
The ETX Telescope is a precision optical instrument designed
to yield a lifetime of rewarding applications. Given the care
and respect due any precision instrument, the ETX will rarely,
if ever, require factory servicing or maintenance. Maintenance
- 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 very gentle strokes of a camel hair
brush or blown off with an ear syringe (available at any
- 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.
- 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 c may be used to clean the inside
surface of the lens. DO NOT use a commercial
photographic lens cleaner.
CAUTION: Do not touch the aluminized circular
surface of the secondary mirror with your finger,
a tissue, or any other object. Scratching of the
mirror surface will otherwise almost certainly
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
- If the ETX 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.
- The super-gloss anodized finish of the ETX's deep-violet
optical tube will fade if left in direct sunlight for prolonged
- Do not leave the ETX telescope inside a sealed car on a
warm summer day; excessive ambient temperatures can
damage the telescope's internal lubrication and electronic
- Two (English-format) hex wrenches are provided with
each ETX Spotting Scope. These wrenches are used as
- Small wrench (.050"): Use the small wrench to tighten
the set-screws of any knobs which may loosen (e.g.,
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-
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2. Storage and Transport
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. 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 front correcting lens.
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3. 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, the view (depending upon the observer's 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
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.
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The following suggestions may be helpful if you are having
difficulty observing through the ETX Spotting Scope:
- Confirm that all the lens or mirror covers have been removed from the telescope.
Never use the ETX telescope to look at the Sun!
Observing the Sun, even for the shortest fraction of a
second, will cause instant and irreversible damage to
the eye, as well as physical damage to the telescope
- Confirm that the Flip-Mirror Control (12, Fig. 20) is in the "down" position if using the #932 Erecting Prism (11, Fig. 20) or doing photography with the ETX. Confirm that the Flip-Mirror Control is in the "up" position if using the Eyepiece Holder (7, Fig. 20) so light is directed to the eyepiece (10, Fig. 20) (see Telescope Controls, page 18).
- When objects appear in the viewfinder but not in the telescope, the viewfinder is not properly aligned with the telescope. Before the ETX is used the first time, the viewfinder must be aligned to the main telescope (see The Viewfinder, page 19). Once aligned, locate objects in the viewfinder first, then move to the main telescope.
- Air conditions inside a warm house or building may distort terrestrial or celestial images and make it difficult, if not impossible, to obtain a sharp focus. For optimal viewing, use the telescope outside in the open air instead of observing through an open or closed window or screen.
- For clear viewing of objects, turn the focus knob (8, Fig. 20) slowly since the "in-focus" point of a telescope is precise.
- The optics within your telescope need time to adjust to the outside ambient temperature to provide the sharpest image. To "cool down" the optics, set your telescope outside for 10 to 15 minutes before you begin observing.
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5. Meade Customer Service
If you have a question concerning your ETX telescope, call Meade Instruments Customer Service
Department at (949) 451-1450, or fax at (949) 451-1460. Customer Service hours are 8:30AM to
4:30PM, Pacific Time, Monday through Friday. In the unlikely event that your ETX requires
factory servicing or repairs, write or call the Meade Customer Service Department first,
before returning the 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
servicing issues can be resolved by telephone, avoiding return of the telescope to the factory.