User Guide

User Guide
Telescopes
Levenhuk
Levenhuk
Levenhuk
Levenhuk
Levenhuk
Skyline
Skyline
Skyline
Skyline
Skyline
PRO
PRO
PRO
PRO
PRO
90 MAK
105 MAK
127 MAK
130 EQ
150 EQ
Congratulations!
Congratulations on your purchase of high-quality Levenhuk telescope!
These telescopes are designed for high-resolution viewing of astronomical objects. With their
precision optics, you will be able to locate and enjoy hundreds of fascinating celestial objects,
including the planets, the Moon, and a variety of deep-sky galaxies, nebulas, and star clusters.
If you have never owned a telescope before, we would like to welcome you to amateur
astronomy. Take some time to familiarize yourself with the night sky. Learn to recognize the
patterns of stars in the major constellations. With a little practice, a little patience, and a
reasonably dark sky away from city lights, you'll find your telescope to be a never-ending source
of wonder, exploration, and relaxation.
These instructions will help you set up, properly use, and care for your telescope. Please read
them thoroughly before getting started.
CAUTION!
Never look directly at the Sun – even for an instant – through your telescope or
finderscope without a professionally made solar filter that completely covers the front of
the instrument, or it may result in permanent eye damage. To avoid damage of the
internal parts of your telescope make sure the front end of the finder scope is covered
with aluminum foil or another non-transparent material. Children should use the
telescope under adult supervision only.
All parts of the telescope will arrive in one box. Be careful unpacking it. We recommend keeping
the original shipping containers. In the event that the telescope needs to be shipped to another
location, having the proper shipping containers will help ensure that your telescope survives the
journey intact. Make sure all the parts are present in the packaging. Be sure to check the box
carefully, as some parts are small. No tools are needed other than the ones provided. All screws
should be tightened securely to eliminate flexing and wobbling, but be careful not to overtighten
them, or the threads may strip.
During assembly (and anytime, for that matter), do not touch the surfaces of the telescope
objective lens, the lenses of the finderscope, or eyepiece lenses with your fingers. The optical
surfaces have delicate coatings on them that can easily be damaged if touched inappropriately.
Never remove any lens assembly from its housing, or the product warranty will be null and void.
Refractor with the EQ3-2 mount
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a
b
A. Dust cap
В. Dew cap
С. Objective lens
D. Telescope tube
Е. Piggyback bracket
F. Finderscope
G. Finderscope bracket
H. Adjustment screws
I. Eyepiece
J. Diagonal mirror
K. Focuser tube
L. Focusing knob
1. R.A. slow-motion control
2. Dec. slow-motion control
3. R.A. lock knob
4. Polarscope holder
5. Altitude adjustment T-bolt
6. Counterweight rod
7. Counterweight
8. Counterweight lock screw
9. Azimuth adjustment knob
10. Dec. lock knob
11. Ring clamps
a. Accessory tray
b. Tripod leg
Refractor with the EQ5 mount
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1.
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6.
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8.
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10.
11.
12.
a.
Polarscope holder
Altitude adjustment T-bolt
Azimuth adjustment knob
Counterweight rod
Counterweight
Counterweight lock screw
R.A. adjustment knob
R.A. lock knob
Dec. lock knob
Dec. adjustment knob
Mounting plate (150 mm/1200 mm)
Ring clamps
Accessory tray
b.
A.
В.
С.
D.
Е.
F.
G.
H.
I.
J.
K.
L.
Tripod leg
Dust cap
Dew cap
Objective lens
Telescope tube
Piggyback bracket
Finderscope
Finderscope bracket
Adjustment screws
Eyepiece
Diagonal mirror
Focuser tube
Focusing knob
Reflector with the EQ3-2 mount
J
A. Dust cap
В. Focuser tube
С. Finderscope
D. Finderscope bracket
Е. Adjustment screws
F. Eyepiece
G. Focusing knob
H. Piggyback bracket
I. Telescope tube
J. Primary mirror
1. Dec. slow-motion control
2. R.A. lock knob
3. Polarscope holder
4. Altitude adjustment T-bolt
5. Counterweight rod
6. Counterweight
7. Counterweight lock screw
8. Azimuth adjustment knob
9. Dec. lock knob
10. Ring clamps
a. Accessory tray
b. Tripod leg
Reflector with the EQ5 mount
1. Mounting plate
2. R.A. slow-motion control
3. Polarscope holder
4. Altitude adjustment T-bolt
5. Azimuth adjustment knob
6. Counterweight
7. Counterweight lock screw
8. Counterweight rod
9. R.A. lock knob
10. Dec. lock knob
11. Dec. slow-motion control
12. Ring clamps
a. Accessory tray
b. Tripod leg
A. Dust cap
В. Focuser tube
С. Finderscope
D. Finderscope bracket
Е. Adjustment screws
F. Eyepiece
G. Focusing knob
H. Piggyback bracket
I. Telescope tube
J. Primary mirror
Maksutov telescope with the EQ5 mount
A. Dust cap
В. Finderscope
С. Focuser lock screw
D. Eyepiece
Е. Diagonal mirror
F. Focusing knob
1. R.A. lock knob
2. Dec. slow-motion control
3. Polarscope
4. Altitude adjustment T-bolt
5. Azimuth adjustment knob
6. Counterweight lock screw
7. Counterweight rod
8. Dec. lock knob
9. Dec. setting circle
a. Tripod leg
b. Accessory tray
c. Height adjustment clamp
Telescope assembly with the EQ3-2 mount
Telescope and mount assembly
Slowly loosen the tripod locking knobs and gently pull out the lower section of each tripod leg.
Tighten the clamps to hold the legs in place. Spread the tripod legs apart to stand the tripod
upright.
Adjust the height of each tripod leg until the tripod head is properly leveled. Note that the
tripod legs may not be the same length when the equatorial mount is leveled.
Place the accessory tray on top of the bracket, and secure it with thumbscrews from
underneath.
Attach the equatorial mount to the tripod head. If the mount does not fit on the tripod, loosen
the azimuth lock knob. Retighten it after assembly.
Take the counterweight rod.
Screw the counterweight rod into the threaded hole on the end of the declination shaft.
Unscrew the threaded cap from the end of the counterweight rod.
Take the counterweight(s) and slide them halfway along the counterweight rod. Tighten the
counterweight thumbscrews.
Replace the threaded cap on the end of the counterweight rod.
Attach the slow-motion controls to the worm gear mechanisms. Tighten the locking screws to secure
the control in place.
Remove the telescope tube from its packaging.
Remove the ring clamps by releasing their thumbscrews and opening their hinges.
Using the bolts provided, fasten the ring clamps to the mount with a wrench.
Place the telescope tube between the rings and balance it. Close the hinges around the
telescope and retighten the thumbscrews. Do not overtighten.
Finderscope assembly
For reflectors:
Take the finderscope.
Insert the finderscope bracket into a holder on the telescope tube and lock it in place with a
thumbscrew.
For refractors:
Take the finderscope bracket. Carefully remove the rubber ring.
Place the ring on the finderscope and position it into the groove halfway along the tube.
Insert the finderscope bracket into a holder on the telescope tube and lock it in place with a
thumbscrew.
Insert the finderscope into the bracket, so that the rubber ring locks it in place.
Eyepiece assembly
For reflectors:
Unthread the thumbscrews on the focuser tube to remove the black plastic cap.
Insert the desired eyepiece and secure it by retightening the thumbscrews.
For refractors and Maksutov telescopes:
Unthread the thumbscrews on the focuser tube.
Insert the diagonal mirror into the focuser tube and secure it by retightening the thumbscrews.
Afterwards, insert the desired eyepiece into the diagonal mirror.
Unthread the thumbscrews on the diagonal mirror.
Telescope assembly with the EQ5 mount
Telescope and mount assembly
Slowly loosen the tripod locking knobs and gently pull out the lower section of each tripod leg.
Tighten the clamps to hold the legs in place. Spread the tripod legs apart to stand the tripod
upright.
Adjust the height of each tripod leg until the tripod head is leveled. Note that the tripod legs
may not be the same length when the equatorial mount is leveled.
Place the accessory tray on top of the bracket, and secure it with thumbscrews from
underneath.
Attach the equatorial mount to the tripod head. If the mount does not fit on the tripod, loosen
the azimuth lock knob. Retighten it after assembly.
Take the counterweight rod.
Screw the counterweight rod into the threaded hole on the end of the declination shaft.
Unscrew the threaded cap from the end of the counterweight rod.
Take the counterweight(s) and slide them halfway along the counterweight rod. Tighten the
counterweight thumbscrews.
Replace the threaded cap on the end of the counterweight rod.
Place the mounting plate (it can be either short or long, depending on the components supplied)
into the bracket and lock it in place with two locking screws. Make sure the holes on the plate
and the mount are aligned.
Remove the telescope tube from its packaging.
Remove the ring clamps by releasing their thumbscrews and opening their hinges.
Using the bolts provided, fasten the ring clamps to the mount with a wrench.
Place the telescope tube between the rings and balance it. Close the hinges around the
telescope and retighten the thumbscrews. Do not overtighten.
Finderscope assembly
For reflectors:
Take the finderscope.
Insert the finderscope bracket into a holder on the telescope tube and lock it in place with
a thumbscrew.
For refractors:
Take the finderscope bracket. Carefully remove the rubber ring.
Place the ring on the finderscope and position it into the groove halfway along the tube.
Insert the finderscope bracket into a holder on the telescope tube and lock it in place with a
thumbscrew.
Insert the finderscope into the bracket, so that the rubber ring locks it in place.
Eyepiece assembly
For reflectors:
Unthread the thumbscrews on the focuser tube to remove the black plastic cap.
Insert the desired eyepiece and secure it by retightening the thumbscrews.
For refractors and Maksutov telescopes:
Unthread the thumbscrews on the focuser tube.
Insert the diagonal mirror into the focuser tube and secure it by retightening the thumbscrews.
Unthread the thumbscrews on the diagonal mirror.
Insert the desired eyepiece into the diagonal mirror and secure it by retightening the
thumbscrews.
Operating the telescope
Optical finderscope
Optical finderscopes are very useful accessories. When they are correctly aligned with the
telescope, objects can be quickly located and brought to the center of the view. Alignment is best
done outdoors in day light when it's easier to locate objects. If it is necessary to refocus your
finderscope, sight it on an object that is at least 500 yards away. For 5x24 and 6x24 finderscopes:
turn the scope end to adjust the focus. For 6x30 finderscopes: loosen the locking ring by
unscrewing it back toward the bracket. The front lens holder can now be turned in and out to
focus. When focus is reached, lock it in position with the locking ring.
Choose a distant object that is at least 500 yards away and point the telescope at the object.
Adjust the telescope so that the object is in the center of the view in your eyepiece. Check the
finderscope to see if the object is also centered on the crosshairs.
For 5x24 and 6x24 finderscopes: use three adjustment screws to center the finderscope crosshairs
on the object. For 6x30 finderscopes: adjust two windage screws
Red dot finder
The red dot finder is a zero magnification pointing tool that uses a coated glass window to
superimpose the image of a small red dot onto the night sky. The red dot finder is equipped with a
variable brightness control, azimuth adjustment knob, and altitude adjustment knob. The finder is
powered by a 3-volt lithium battery located underneath at the front. To use the red dot finder,
simply look through the sight tube and move your telescope until the red dot overlaps the object.
Make sure to keep both eyes open when sighting.
Scope
Azimuth adjustment knob
Brightness control
Altitude adjustment knob
Battery compartment cover
Like all finderscopes, the red dot finder must be properly aligned with the telescope before use.
This is a simple process using the azimuth and altitude adjustment knobs.
Open the battery compartment by pulling down the cover and remove the plastic shipping cover
over the battery.
Turn on the red dot finder by rotating the variable brightness control clockwise until you hear a
click. Continue rotating the control knob to increase the brightness level.
Insert a low power eyepiece into the focuser. Locate a bright object and aim the telescope so that
the object is in the center of the field of view.
With both eyes open, look through the sight tube at the object. If the red dot overlaps the object,
your red dot finder is perfectly aligned. If not, turn its azimuth and altitude adjustment knob until
the red dot overlaps the object.
Balancing the telescope
A telescope should be balanced before each observing session. Balancing reduces stress on the
telescope mount and allows precise slow-motion movements. A balanced telescope is especially
crucial when using the optional clock drive for astrophotography. The telescope should be
balanced after all accessories (eyepiece, camera, etc.) have been attached. Before balancing your
telescope, make sure that your tripod is balanced and on a stable surface. For photography, point
the telescope in the direction you will be taking photos before performing the balancing steps.
R.A. balancing
For best results, adjust the altitude of the mount to between 15º and 30º if possible, by using the
altitude adjustment T-bolt.
Slowly unlock the R.A. and Dec. lock knobs. Rotate the telescope until both the optical tube and
the counterweight rod are horizontal to the ground, and the telescope tube is to the side of the
mount.
Tighten the Dec. lock knob.
Move the counterweights along the counterweight rod until the telescope is balanced and remains
stationary when released.
Tighten the counterweight screws to secure the counterweights.
Dec. balancing
All accessories should be attached to the telescope before balancing around the declination axis.
The R.A. balancing should be done before proceeding with Dec. balancing.
For best results, adjust the altitude of the mount to between 60º and 75º if possible.
Release the R.A. lock knob and rotate around the R.A. axis so that the counterweight rod is in a
horizontal position. Tighten the R.A. lock knob.
Unlock the Dec. lock knob and rotate the telescope tube until it is parallel to the ground.
Slowly release the telescope and determine in which direction it rotates. Loosen the telescope
ring clamps and slide the telescope tube forward or backward between the rings until it is
balanced.
Once the telescope no longer rotates from its parallel starting position, retighten the tube rings
and the Dec. lock knob. Reset the altitude axis to your local latitude.
Operating the mount
The mount has controls for both conventional altitude (up-down) and azimuth (left-right)
directions of motion. These two adjustments are suggested for large direction changes and for
terrestrial viewing. To adjust azimuth, loosen the big knob under the mount base and rotate the
mount head about the azimuth axis. Use the altitude adjustment T-bolts to set the required
altitude.
In addition, the mount has R.A. (hour angle) and Dec. controls for polar-aligned astronomical
observing. Loosen the lock knobs to make large direction changes. Use the slow-motion controls
for fine adjustment after the lock knobs have both been locked. An additional scale is included
for the altitude axis. This allows polar alignment at your local latitude.
Dec. adjustment
R.A. scale
R.A. adjustment
R.A. adjustment
Altitude adjustment
(up-down)
R.A. fine adjustment
Azimuth adjustment (left-right)
Dec. fine adjustment
Barlow lens
A Barlow lens increases the magnifying power of an eyepiece, while reducing the field of view. It
expands the cone of the focused light before it reaches the focal point, so that the telescope's
focal length appears longer to the eyepiece. In addition to increasing magnification, the benefits
of using a Barlow lens include improved eye relief, and reduced spherical aberration of the
eyepiece. For this reason, a Barlow plus a lens often outperform a single lens producing the same
magnification. And the best advantage is that a Barlow lens can potentially double the number of
eyepieces in your collection.
Eyepiece
Barlow lens
Diagonal mirror
Focusing
Slowly rotate the focus knobs under the focuser one way or the
other until the image in the eyepiece is sharp. The image usually
has to be finely refocused over time, due to small variations
caused by temperature changes, flexures, etc. This often
happens with short focal ratio telescopes, particularly when they
haven't yet reached outside temperature. Refocusing is almost
always necessary when you change an eyepiece, add or remove a
Barlow lens.
Polar adjustment
In order for your telescope to track objects in the sky you have to align your mount. This means
tilting the head over so that it points to the North (or South) celestial pole. For people in the
Northern Hemisphere this is rather easy as the bright star Polaris is very near the North Celestial
Pole. For casual observing, rough polar alignment is adequate. Make sure your equatorial mount is
leveled and the finderscope is aligned with the telescope before beginning.
Loosen the Dec. lock knob and rotate the telescope tube
until the pointer on the setting circle reads 90°. Retighten
the Dec. lock knob. Loosen the azimuth lock knob and move
the mount so that the R.A. axis points roughly at Polaris. Use
the two azimuth adjustment knobs above the "N" to make
fine adjustments in azimuth if needed. For more accurate
alignment, look through the finderscope and center the
Polaris on the crosshairs using the azimuth and latitude
adjustment knobs.
After a while you will notice your target drifting slowly North
or South depending on the direction of the pole relative to
Polaris. To keep the target in the center of the view, turn
only the R.A. slow-motion control.
After your telescope is polar aligned, no further adjustments
in the azimuth and latitude of the mount should be made in
the observing session, nor should you move the tripod. Only
movements in R.A. and DEC axis should be made in order to
keep an object in the field.
50
40 30
20 10 0
90 80 70 60
Look up your latitude on a map, road maps are good for this
purpose. Now look at the side of your mount head, there
you will see a scale running from 0 to 90°. Loosen the
mount latch slightly rotating the lock handle
counterclockwise. A thumbscrew located underneath the
mount head pushes the latch plate, thus changing the
angle. Turn the screw until the pointer on the latitude scale
is set at the latitude of your observation site.
Ursa Major
Ursa Minor
+
Polaris
Cassiopeia
In the Southern Hemisphere you must align the mount to the SCP by locating its position with star
patterns, without the convenience of a nearby bright star. The closest star is the faint 5.5-mag.
Sigma Octantis which is about one degree away. Two sets of pointers which help to locate the SCP
are α and β Crucis (in the Southern Cross) and a pointer running at a right angle to a line
connecting α and β Centauri.
Tracking celestial objects
When observing through a telescope, astronomical objects appear to move slowly through the
telescope's field of view. When the mount is correctly polar aligned, you only need to turn the
R.A. slow-motion control to follow or track objects as they move through the field. A R.A. motor
drive can be added to automatically track celestial objects by counteracting the rotation of Earth.
The rotation speed of the R.A. drive matches the rotation rate of Earth for stars to appear
stationary in the telescope eyepiece. Different tracking speeds are also available in some models.
A second drive can be added to give Dec. control which is very useful for astrophotography.
The quickest way to find objects is to learn the constellations and use the finderscope, but if the
object is too faint you may want to use setting circles on an equatorial mount. Setting circles
allow you to locate celestial objects whose celestial coordinates have been determined from star
charts. Your telescope must be Polar aligned and the R.A. setting circle must be calibrated before
using the setting circles. The Dec. setting circle was calibrated at the factory and no additional
calibration is required for it.
The telescope's R.A. setting circle is scaled in hours, from 1 to 24, with small lines in between
representing 10 minute increments. The upper set of numbers applies to observations in the
Northern Hemisphere, while the numbers below them apply to observations in the Southern
Hemisphere.
Setting (calibrating) the R.A. setting circle
In order to set your Right Ascension circle you must first find a star in your field of view with
known coordinates. A good one would be the 0.0 magnitude star Vega in the Constellation Lyra.
From a star chart we know the R.A. coordinate of Vega is 18h 36m.
Loosen the R.A. and DEC. lock knobs on the mount and adjust the telescope so that Vega is
centered in the field of view of the eyepiece. Tighten the R.A. and DEC. lock knobs to lock the
mount in place. Now rotate the R.A. setting circle until it reads 18h36m. You are now ready to use
the setting circles to find objects in the sky.
R.A. adjustment
R.A. settling circle
Arrow
Example: Finding the faint planetary nebula M57; "The Ring”
From a star chart, we know the coordinates of the Ring are Dec. 33º and R.A. 18h52m. Unlock the
Dec. lock knob and rotate your telescope in Dec. until the pointer on the Dec. setting circle reads
33º. Re-tighten the Dec. lock knob.
Loosen the R.A. lock knob and rotate the telescope in R.A. until the pointer on the R.A. setting
circle reads 18h52m (do not move the R.A. circle). Re-tighten the R.A. lock knob. Now look
through the finderscope to see if you have found M57. Adjust the telescope with R.A. and Dec.
slow-motion controls until M57 is centered in the finderscope. Now look through the telescope
using a low power eyepiece. Center M57 in the field of view of the eyepiece.
The setting circles will get you close to the object you wish to observe, but are not accurate
enough to put it in the center of your red dot finder's field of view. The accuracy of your setting
circles also depends on how accurately your telescope is polar aligned.
Zenith
Mount aligned on
North Celestial Pole
Object you
are viewing
Right
Ascension
Polaris
Declination
Latitude
Meridian
Line
Plane of local horizon
Nadir
Plane of Celestial
Equator
Apparent
movement
of stars
Pointing your telescope
A German Equatorial mount has an adjustment, sometimes called a wedge, which tilts the
mount's polar axis so that it points at the appropriate Celestial Pole (NCP or SCP). Once the mount
has been polar aligned, it needs to be rotated around the polar axis only to keep an object
centered. Do not reposition the mount base or change the latitude setting. The mount has already
been correctly aligned for your geographical location (i.e. Latitude), and all remaining telescope
pointing is done by rotating the telescope tube around the polar (R.A.) and declination axes.
A problem for many beginners is recognizing that a
polar-aligned, equatorial mount acts like an alt-azimuth
mount which has been aligned to a celestial pole. The
wedge tilts the mount to an angle equal to the
observer's Latitude, and therefore it swivels around a
plane which is parallel to the celestial (and Earth's)
equator. This is now its "horizon"; but remember that
part of the new horizon is usually blocked by Earth.
This new "azimuth" motion is called Right Ascension
(R.A.). In addition, the mount swivels North (+) and
South (-) from the Celestial Equator towards the
celestial poles. This plus or minus "altitude" from the
celestial equator is called Declination (Dec.).
Now, consider pointing the telescope to the western or
eastern horizon. If the counterweight is pointing North,
the telescope can be swiveled from one horizon to the
other around the Dec. axis in an arc that passes through
the NCP (any Dec. arc will pass through the NCP if the
mount is polar-aligned). It can be seen then that if the
optical tube needs to be pointed at an object north or
south of this arc, it has to be also rotated around the
R.A. axis.
Pointing in any direction other than due North requires
a combination of R.A. and Dec. positions. This can be
visualized as a series of Dec. arcs, each resulting from
the position of rotation around the R.A. axis. In
practice however, the telescope is usually pointed, with
the aid of a finderscope, by loosening both the R.A. and
Dec. locks and swiveling the mount around both axes
until the object is centered in the eyepiece. The
swiveling is best done by placing one hand on the
telescope tube and the other on the counterweight rod,
so that the movement around both axes is smooth, and
no extra lateral force is applied to the axis-bearings.
When the object is centered, make sure the R.A. and
Dec. locks are both retightened to hold the object in
the field of view and allow tracking by adjusting R.A.
only.
Celestial Pole
Pointing at an object, for example to the South, can often be achieved with the tube positioned
on either side of the mount. When there is a choice of sides, particularly when there could be a
long observing period, the East side should be chosen in the Northern Hemisphere because
tracking in R.A. will move it away from the mount's legs. This is particularly important when using
an R.A. motor, because if the optical tube jambs against the mount's legs, it can result in damage
to the motor and/or the gears.
Telescopes with long focal lengths often have a "blind spot" when pointing near the zenith,
because the eyepiece-end of the optical tube bumps into the mount's legs. To avoid this, the tube
can be very carefully slipped up inside the ring clamps. This can be done safely because the tube
is pointing almost vertically, and therefore moving it does not cause a Dec. balance problem. It is
very important to move the tube back to the Dec. balanced position before observing other sky
areas.
Something which can also be a problem is that the optical tube often rotates so that the
eyepiece, finderscope and the focusing knobs are in less convenient positions. The diagonal
mirror can be rotated to adjust the eyepiece. However, to adjust the positions of the finderscope
and focusing knobs, loosen the tube rings holding the telescope tube and gently rotate it. Do this
when you are going to observe an area for while, as it is inconvenient to repeat every time you
briefly go to a new area.
Finally, there are a few things to consider to ensure that you are comfortable during the viewing
session. First is setting the height of the mount above the ground by adjusting the tripod legs. You
must consider the height that you want your eyepiece to be, and if possible plan on sitting on a
comfortable chair or stool. Very long optical tubes need to be mounted higher or you will end up
crouching or lying on the ground when looking at objects near the zenith. However, a short
optical tube can be mounted lower so that there is less movement due to vibration sources, such
as wind. This is something that should be decided before going through the effort of polar
aligning the mount.
Choosing the appropriate eyepiece
The magnification produced by a telescope is determined by the focal length of the eyepiece that
is used with it. To determine a magnification for your telescope, divide its focal length by the
focal length of the eyepieces you are going to use. For example, a 10 mm focal length eyepiece
will give 80x magnification with an 800 mm focal length telescope.
Magnification = Focal length of the telescope / Focal length of the eyepiece
e.g. 800mm / 10mm = 80x
When you are observing astronomical objects, you are looking through a column of air that
reaches to the edge of space and that column seldom stays still. Similarly, when viewing over land
you are often looking through heat waves radiating from the ground, houses, buildings, etc. Your
telescope may yield very high magnifications, but what you end up magnifying is all the
turbulence between the telescope and the object. A good rule of thumb is that practical
magnification of a telescope is about 2x per 1 mm of aperture under good conditions.
Field of view
The area that you see through your telescope is called the true (or actual) field of view and is
determined by the optical design of the eyepiece. Every eyepiece has a value, called the apparent
field of view, which is supplied by the manufacturer. Field of view is usually measured in degrees
and/or arc-minutes (1 deg. equals 60 arc-minutes). The true field of view produced by your
telescope is calculated by dividing the apparent field of view of an eyepiece by the magnification
that you have just calculated for the combination. For example, if your 10 mm eyepiece has an
apparent field of view of 52 degrees, then the true field of view is 0.65 degrees or 39 arc-minutes.
True Field of View = Apparent Field of View / Magnification
e.g. 52° / 80X = 0.65°
To put this in perspective, the Moon is about 0.5° or 30 arc-minutes in diameter, so this
combination would be fine for viewing the whole moon with a little room to spare. Remember, too
much magnification and too small a field of view can make it very hard to find things. It is usually
best to start at a lower magnification with its wider FOV and then increase the magnification
when you have found what you are looking for. First find the Moon then look at the shadows in the
craters.
Exit pupil
Knowing this value for a telescope-eyepiece combination tells you whether your eye is receiving
all of the light gathered by the primary lens or mirror. The average person has a fully dilated pupil
diameter of about 7 mm. This value varies a bit from person to person, is less until your eyes
become fully dark adapted and decreases as you get older. To determine exit pupil, you have to
divide the diameter of the aperture of your telescope by the magnification.
Exit Pupil = Aperture in mm / Magnification
For example, a 200 mm telescope with an 8 mm eyepiece produces a magnification of 25x and an
exit pupil of 8mm. This combination can probably be used by a younger person but would not be
of much value to a senior citizen. The same telescope used with a 6 mm eyepiece gives a
magnification of about 33x and an exit pupil of 6 mm, which should be fine for most dark adapted
eyes.
Observing celestial objects
Sky conditions are usually defined by two atmospheric characteristics, seeing, or the steadiness of
the air, and transparency, light scattering due to the amount of water vapor and particles in the
air. When you observe the Moon or planets, and they appear as though water is running over them,
you probably have bad "seeing" because you are observing through turbulent air. In conditions of
good seeing, the stars appear steady, without twinkling. Ideal transparency is when the sky is inky
black and the air is unpolluted.
Travel to the best site that is reasonably accessible. It should be away from city lights, and upwind
from any source of air pollution. Always choose as high an elevation as possible; this will get you
above some of the lights and pollution and will ensure that you aren't in any ground fog.
Sometimes low fog helps by blocking light pollution if you get above it. Try to have an
unobstructed view of the horizon, especially the southern horizon if you are in the Northern
Hemisphere and vice versa. Remember that the darkest sky is usually at the zenith, directly above
your head. Do not try to observe anything that passes near hills or buildings along its route. Even
extremely light winds can cause major air turbulence as they flow over the top of a building or a
wall. Observing through a window is not recommended because the window glass will distort
images considerably. And an open window can be even worse, since warmer indoor air will escape
out the window, causing turbulence which also affects images. All in all, astronomy is an outdoor
activity. Reflectors require about 10 minutes to adapt to the outside temperature, while
refractors require more than 30 minutes. If you are using an equatorial mount, you can spend this
time polar aligning your telescope.
The best conditions will have still air, and obviously, a clear view of the sky. Some clouds may be
present, as often broken clouds provide excellent seeing. Do not view immediately after sunset.
After the sun goes down, the ground is still cooling, causing air turbulence. As the night goes on,
not only will the seeing improve, but air pollution and ground lights will often diminish as well.
The best time for observations is early morning. Objects are best observed as they cross the
meridian, which is an imaginary line that runs through the Zenith, due North-South. This is the
point at which objects reach their highest points in the sky, and negative atmospheric effects are
reduced to their minimum.
Telescopes require at least 10 to 30 minutes to cool down to outside temperature. This may take
longer if there is a big difference between the temperature of the telescope and the outside air.
This minimizes heat wave distortion inside telescope tube. Allow a longer cooling time for larger
optics. If you are using an equatorial mount, use this time for polar alignment.
Try to avoid any electric lights for 30 minutes prior to observing. This allows your pupils to dilate
to their maximum diameter and build up the levels of optical pigments, which are rapidly lost if
exposed to bright light. To avoid fatigue, observe with both eyes open. If you find this too
distracting, cover the eye you are not using with your hand or an eye patch. Use peripheral vision
on dim objects, as the center of your eye is the least sensitive to low light levels. When viewing a
dim object, don't look directly at it. Instead, look slightly to the side, and the object will appear
brighter.
Collimation
Collimation is the process of aligning the mirrors of your telescope so that they work together to
deliver properly focused light to your eyepiece. By observing out-of-focus star images, you can
test whether the optics of your telescope are aligned. Place a star in the center of the field of
view and move the focuser so that the image is slightly out of focus. If the seeing conditions are
good, you will see a central circle of light (the Airy disc) surrounded by a number of diffraction
rings. If the rings are symmetrical about the Airy disc, the telescope's optics is correctly
collimated.
Correctly aligned
Needs collimation
If you do not have a collimating tool, we suggest that you make a "collimating cap" out of a plastic
35mm film canister (black with gray lid). Drill or punch a small pinhole in the exact center of the
lid and cut off the bottom of the canister. This device will keep your eye centered of the focuser
tube. Insert the collimating cap into the focuser instead of a regular eyepiece.
Collimation is a painless process and works like this:
Pull off the lens cap which covers the front of the telescope and look inside the telescope tube. At
the bottom you will see the primary mirror held in place by three clips 120º apart, and at the top
the small oval secondary mirror held in a support and tilted 45º toward the focuser away from the
tube wall.
Focucer
Support for secondary mirror
Primary mirror
Secondary mirror
The secondary mirror is aligned by adjusting the three smaller screws surrounding the central
bolt. The primary mirror is adjusted by the three adjusting screws at the back of your scope. The
three locking screws beside them serve to hold the mirror in place after collimation.
Primary mirror
Mirror cell
Adjusting screw
Locking screw
Aligning the secondary mirror
Point the telescope at a lit wall and insert the collimating cap into the focuser instead of a regular
eyepiece. Look into the focuser through your collimating cap. You may have to rotate the focus
knob a few turns until the reflected image of the focuser is out of your view.
Note: keep your eye against the back of the focus tube if collimating without a collimating cap.
Ignore the reflected image of the collimating cap or your eye for now, instead look for the three
clips holding the primary mirror in place. If you can't see them, it means that you will have to
adjust the three bolts on the top of the secondary mirror holder, with an Allen wrench or Phillips
screwdriver. You will have to alternately loosen one and then compensate for the slack by
tightening the other two. Stop when you see all three mirror clips. Make sure that all three small
alignment screws are tightened to secure the secondary mirror in place.
Primary mirror clip
Primary mirror clip
Ignore the reflected
Image for now
Primary mirror clip
Primary mirror clip
Aligning the primary mirror
If you see 3 large screws protruding from the back of your telescope and 3 small Phillips screws
besides them, the Phillips screws are the locking screws and the large screws are the adjusting
screws.
If you see 6 Phillips screws but 3 protruding from the back of your telescope, the 3 protruding
screws are locking screws and the ones next to them are adjusting screws.
If you see 3 hex bolts and 3 Phillips screws, the hex bolts are the locking bolts and the Phillips
screws are the adjusting screws. You will need an Allen wrench to adjust the locking bolts.
Now run your hand around the front of your telescope keeping your eye to the focuser, you will
see the reflected image of your hand. The idea here being to see which way the primary mirror is
defected; do this by stopping at the point where the reflected image of the secondary mirror is
closest to the primary mirrors' edge.
Secondary
mirror
Primary
mirror
Keep your hand
here
Both mirrors aligned
with collimating cap in
Both mirrors aligned with
eye looking in focuser
When you get to that point, stop and keep your hand there while looking at the back end of your
telescope, is there an adjusting screw there? If there is you will want to loosen it (turn the screw
to the left) to bring the mirror away from that point. If there isn't an adjusting screw there, then
go across to the other side and tighten the adjusting screw on the other side. This will gradually
bring the mirror in line until it looks like shown on the picture. It helps to have a friend to help
with primary mirror collimation. Have your partner adjust the adjusting screws according to your
directions while you look in the focuser.
After dark go out and point your telescope at Polaris, the North Star. With an eyepiece in the
focuser, bring the image out of focus. You will see the same image, only now it will be illuminated
by starlight. If necessary, repeat the collimating process only keep the star centered while
tweaking the mirror.
Camera adapter
To attach a camera to your telescope you may need an adapter to get the camera focused. Some
reflectors require wider motion range than the one allowed by the focuser; some refractors are
designed to be used with diagonal mirrors and thus need a longer focal length when used with
camera.
To achieve that, simply attach an extender to the focuser of your telescope and then attach the
camera with a T-adapter to the extender.
Focuser
Eyepiece holder
Extender
T-adapter
Camera
Maintenance
Replace the dust cap over the front end of the telescope whenever it is not in use. This prevents
dust from settling on the mirror or lens surfaces. Be careful when cleaning optics and try not to
damage the coating. Use only special cleaning wipes.
Specifications
Specification
Levenhuk Skyline PRO 90 MAK
Optical design
Aperture
Focal length
Highest practical power
Limiting stellar magnitude
Resolution threshold
Eyepiece
Finderscope
Mount
Tripod
Maksutov-Cassegrain
90 mm
1250 mm; f/13.9
180x
11.7
1.5 arcsec.
1.25"; SUPER10 & SUPER20
Red dot finder
EQ1
aluminum
Levenhuk Skyline PRO 105 MAK
Optical design
Aperture
Focal length
Highest practical power
Limiting stellar magnitude
Resolution threshold
Eyepiece
Finderscope
Mount
Tripod
Maksutov-Cassegrain
102 mm
1300 mm; f/12.8
200x
12.0
1.3 arcsec.
1.25"; SUPER10 & SUPER20
6x30
EQ2
aluminum; 700-1250 mm
Levenhuk Skyline PRO 130 EQ
Newtonian reflector
130 mm
650 mm; f/5
260x
13.3
0.9 arcsec.
1.25" & 2" (with an adapter);
SUPER10 & SUPER20
Finderscope 6x30, red dot finder
Mount EQ3
Tripod Stainless steel; 710-1230 mm
Optical design
Aperture
Focal length
Highest practical power
Limiting stellar magnitude
Resolution threshold
Eyepiece
Levenhuk Skyline PRO 150 EQ
Newtonian reflector
150 mm
750 mm; f/5
300x
12.9
0.9 arcsec.
1.25" & 2" (with an adapter);
SUPER10 & SUPER25
Finderscope 6x30
Mount EQ3
Tripod Stainless steel; 840-1170 mm
Optical design
Aperture
Focal length
Highest practical power
Limiting stellar magnitude
Resolution threshold
Eyepiece
Levenhuk Skyline PRO 127 MAK
Optical design
Aperture
Focal length
Highest practical power
Limiting stellar magnitude
Resolution threshold
Eyepiece
Maksutov-Cassegrain
127 mm
1500 mm; f/11.8
250x
12.5
1.1 arcsec.
1.25" & 2" (with an adapter);
PL10 & PL25
Finderscope 6x30
Mount EQ3
Tripod aluminum; 700-1250 mm
Warranty
The Vendor guarantees that the quality of the Levenhuk product purchased complies with the
technical documentation requirements on conditions that the consumer observes rules of
transportation, storage conditions and operating instructions.
Levenhuk Ltd. warrants the product against defects in materials.
During the warranty period the Buyer can return the defect product to the Vendor or to Levenhuk
service center. Levenhuk Ltd. will repair or replace the defect product at its own discretion.
No claims are accepted in case the properly filled warranty slip is absent or contains corrections,
or if the defect product has not been provided by the Buyer. The manufacturer or the seller is not
liable for any damages caused by misuse of the product. No guarantee is provided in cases the
product was used for purposes other than that intended or has mechanical damages, scratches,
cracks, optics damages, as well as in cases the product is broken-down due to impact damages,
squeezing or stretching or the product has been disassembled or repaired by unauthorized
personnel.
This warranty does not cover components and/or accessories with limited use period, batteries,
etc.
The period of warranty is 3 (three) years beginning on the date of purchase. Please keep the
warranty slip along with your receipt.
For more details on the after-sales service please contact Levenhuk.
www.levenhuk.com
Purchase date ___________________________ Signature __________________________ Stamp
Planisphere Levenhuk M20 / Levenhuk M12
If you cannot fall asleep at night, seeing the starry sky outside, and visions of not so distant
universe trouble your mind at times, we have just the thing for you. The Planisphere will help you
determine the current position of stars in the sky on any given day and at any time. The star
chart shows stars of up to third apparent magnitude of the northern celestial hemisphere and a
part of the southern celestial hemisphere.
Levenhuk Space Posters
Ever wondered what is the size of the Sun? How many expeditions there were to the Moon? What
will happen to the Sun in 8 billion years? Levenhuk® Space posters answer these and many other
questions. Each poster provides you with visual and nicely arranged blocks of trivia on planets,
stars and satellites proportions, as well as weight, age, composition and formation history of each
star.
Levenhuk Accessories
Levenhuk optics cleaning tools
The Levenhuk series of cleaning tools is all you need to keep your optics
clean and durable and to maintain its excellent quality.
Developed and manufactured for Levenhuk, Ltd. Long Island City, NY 11101 USA.
Levenhuk® is a registered trademark of Levenhuk,
Ltd. Copyright © 2006-2012 Levenhuk Ltd. All rights reserved