Omegon 750 EQ-3 User manual

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Instruction Manual
Omegon 150/750 EQ-3
English version 12.2014 Rev A

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The Omegon® 150/750 EQ-3
Congratulations on the purchase of the new Omegon® 150/750 EQ-3. This telescope will give you
hours of fun, with its all optical glass mirror and light gathering capability, it is the ideal companion
to start in the world of amateur astronomy. With this telescope you will be able to see the craters on
the Moon, star clusters, some nebulae, the Jupiter disc features and its Galilean moons and the rings
of Saturn. We have included many accessories, so it will be easy to use this telescope.
1. Included parts
We have included several accessories that will make the use of the telescope easier and fun, please
take a look at the list of the parts so you can identify them in the future.
1. & 2. Two eyepieces 1.25” (31.75mm); a Plössl 25mm and a Plössl 6.5mm eyepiece;
3. 2x magnification Barlow Lens;
4. Red-dot Finderscope;
2. Getting Started.
It is very simple to get started. Here is how
the telescope works. The telescope aperture
should point to the object being observed.
The mirror in the back of the tube will gather
the light coming from the object and reflects
it to the secondary mirror that brings it to the
eyepiece. Close to the aperture there is the
focuser. The focuser moves up and down to
get a precise focused image. At the focuser
one can use the supplied accessories.
Different accessory combinations give
different results, such as different image
magnifications or correct image for example.
All this will be explained in detail on the next
pages.
3. Assembly. Start by assembling tripod
(figure 2), place the accessory tray (figure 3), the accessory tray will be useful when observing as a
platform for accessories. Next the equatorial mount should fit the top of the tripod (figure 4).
Tighten it carefully, all telescope weight will be laying on it. Thread the counter-weight shaft (figure
5) and the fine adjustment knobs (figure 6), make also sure these are well tightened. Slide the
counterweight on the shaft it should be placed at half the shaft length (figure 7). Make sure the foot-
saver is also in the right place at the end of the shaft, it prevents the counterweight from dropping
accidentally. The two supplied optical tube rings should be placed as shown (figure 8). Insert the
optical tube and make sure to tighten the ring knobs (figure 9). They prevent the tube from sliding
off. Now it is time to place the finderscope (remove the finderscope thumbnuts and place the
finderscope pointing to the telescope’s aperture – figure 10 and 11). By unlocking the two knobs
(figure 12) you can point the telescope to any direction. Before starting to use the telescope one last
thing is required, you need to balance the telescope. Loosen the tube rings so the tube slides and
adjust it so it is balanced. Do the same for the counterweight (figure 13).
Figure 1. Parts list.

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Figure 2. Assemble the tripod.
Figure 3. Place accessory tray.
Figure 4. Place the equatorial head.
Figure 5. Thread the counterweight shaft.
Figure 6. Place the hand knobs.
Figure 7. Slide counterweight and the Foot-Saver.

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Figure 8. Place tube rings and tighten.
Figure 9. Use the two knobs to prevent the tube from sliding.
Figure 10. Remove the finderscope nuts.
Figure 12. The two axis locking knobs.
Figure 11. Place finderscope and thread the thumbnuts
Figure 13. Balance both telescope’s axis.

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4. How to use and how to align the finderscope?
4.1. A distant object is centered at the
telescope’s field of view with an eyepiece. In this
example we have a house with a chimney. The
chimney is the reference point to place at the
center of the field of view. We first look through
the telescope with the lowest magnification
possible (PL25mm should be preferable) so we
have the widest field of view.
4.2. Looking through the finderscope (it should
be powered on) we see the same building but in
this case the red dot and chimney are not
centered. We adjust the finderscope using the
two thumbscrews (figure below) so that the
finderscope red point moves slightly until it
matches the chimney. This is enough to correct
the objects position in the finderscope. Trial and
error is required to get a satisfactory result.
4.3. After playing with the three findercope
thumbscrews and some trial and error we get the
finderscope recticle close to the center (in this
case the chimney). The finderscope is now ready
to use!

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5. What can been seen with this telescope?
Below you will find some examples of what you can expect to see when using this telescope.
5.1. The Moon is one of the most spectular objects
to be seen through a telescope. Even a small
telescope will reveal high detail of the Moon’s
surface. You will be able to see the craters on the
Moon’s surface and other features like the Marea.
The moon is a very bright object. It is better
observed when the Moon is not full. Try the
crescent Moon and look for features along the
terminator (between illumated and dark surfaces).
5.2. Jupiter is the biggest planet of our solar system.
It is also on of the favorite targets for beginners.
Galileo was able to discover that the four tiny dots
that turn around the planet were in fact part of
Jupiters system of moons. With this telescope you
will be able not only to see Jupiter’s planet disc with
its two major discernible bands but also its biggest
moons, Io, Europa, Ganymedes and Callisto.
4.3. The “lord of the rings” of the night skies, Saturn
is5by far the most popular target for small
telescopes. Saturn’s rings are discernible even at
60x magnification. In a very good night you will be
able to see the Cassini’s division (the darker band
on the Saturn’s rings).

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6. Using the accessories, a bit of math to
understand how all it works.
Using the accessories is easy and fun. To
change magnification simply swap eyepieces.
To get more magnification simply use the
barlow lens. But how does all of this work?
6.1. Power (magnification)
Your telescope has a focal length of 750mm.
This is approximately the distance between
the telescope lens and its focal point (very
similar to the distance between the focus
point of a loupe and the loupe lens). This is a
very important feature that allows to
determine several interesting facts such as
magnification.
The magnification is determined by the
telescopes focal length and the used
eyepiece. You probably noticed that the two
supplied eyepieces are PL25mm and
PL6.5mm. This means that the PL25mm is a
25mm focal length eyepiece, while the
PL6.5mm is a 6.5mm focal length eyepiece.
To determine the magnification just divide the
telescope’s focal length by the eyepiece’s
focal length. Lets give an example for our
telescope and the supplied eyepieces:
Telescope focal length is 750mm
PL25 eyepiece focal length is 25mm
750𝑚𝑚
25𝑚𝑚 =50 𝑝𝑜𝑤𝑒𝑟
This means that the PL25 eyepiece provides a
50x power (magnification). This seems low,
but try it, you will see a bright image a lot of
good detail.
6.2. Barlow Lens (not included)
The barlow lens is a very interesting device
(not included). It is a negative lens that
multiplies the telescopes focal length. So a 2x
Barlow multiplies the original focal length by
2x, in this case 750𝑚𝑚 𝑥 2 = 1500𝑚𝑚.
A 3x Barlow lens multiplies it by 3x.
When used with the PL25 eyepiece you get 2x
the power obtained before
50 𝑝𝑜𝑤𝑒𝑟 𝑋 2𝑥 𝐵𝑎𝑟𝑙𝑜𝑤 = 100 𝑝𝑜𝑤𝑒𝑟
6.3. Erecting lens (not included)
The erecting lens gets you an upright image
view with the telescope. It also adds some
power like the barlow lens. The supplied
erecting lens provides an extra 1.5x power.
Here are some examples on how to use the
accessories.
Some possible accessory combinations
Terrestrial
View
Moon
Deep Sky
Jupiter and
Saturn
PL25mm
Yes
Yes
Yes
PL6.5mm
Yes
Power
50x
50x
50x
115x
ATTENTION! Never look at the Sun through a telescope. Concentrated Sun
light may cause serious eye injury. Children should use only with adult
supervision
For any other questions please feel free to drop a line or visit our website at: http://www.astroshop.de
nimax Gmbh Otto-Lilienthal-Str. 9
D-86899 Landsberg am Lech

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7. Troubleshooting and frequently asked questions
Q: I can’t focus my telescope, I only get a bright circle.
R: Make sure you have inserted the Diagonal and an eyepiece (start by the lowest power eyepiece –
PL25mm). Point to a distant object during the day and proceed as described in 4.
Q: I get a mirrored view of the objects. Like if they were reversed, and R shows up like ᴙ.
R: This is caused by the Diagonal Mirror. It has a mirror inside. To get a corrected image it is
necessary to use the Erecting Lens and the Eyepiece as shown below.
Q: When I use the barlow lens and the PL6.5mm eyepiece the image is so dark I can hardly see
anything.
A: Power should be used with moderation. It depends on how stable the atmosphere is, too much
turbulence causes image distortion. Usually the limit is 2x for each millimeter of the telescope
aperture. In this case, the telescope has an aperture of 150mm so in a very good night you should be
able to reach 300x. The more magnified the image, is the darker it gets.
Q: Is my telescope compatible with other eyepieces ?
A: Omegon® telescopes are compatible with all telescope eyepieces from different manufacturers as
long as the eyepiece is a 1.25” (or 31.75mm) size eyepiece. If you would like to test an eyepiece from
a fellow astronomer go ahead. Different eyepieces provide different visual experiences.
Q: I want to use my telescope to take pictures.
A: This telescope is designed for visual use. It doesn’t mean it can’t be used for photography, however
it will be hard to get high quality pictures with this telescope. If you have a smartphone you can shoot
the Moon or some terrestrial objects. Search online for digiscoping and afocal photography.
Q: The stars only appear as points in the telescope.
A: Stars will always appear only as points, even in the largest telescopes in the world. It is more
interesting for beginners to observe two-dimensional objects, such the moon or planets. Once you
find these, you will be able to start learning about the astronomical calendar.
Q: I would like to observe the Sun.
A: An appropriate solar filter, placed over the objective, is essential for observing the sun. These are
available as plastic foil or glass filters. They allow only a tiny and harmless fraction of sunlight into
the telescope, when securely positioned over the objective, so allowing you to observe the sun in
complete safety. Eyepiece solar filters (not available from us) should be avoided at all costs as they
are considered unsafe. Note: Never look directly at the sun through a telescope without an
objective solar filter!
Q: I can’t see anything when I look through my telescope.
A: The telescope is only suitable for astronomical observing and when used outside at night.
Observing from inside the house or during the day is usually not possible.
The dust caps must first be removed and an eyepiece inserted before you can start observing. Are
you sure you have removed all the dust caps, not just the small ones? If you have not, then no light
will enter the telescope and everything will appear black.