VOYAGER® 4.5 INCH DOBSONIAN TELESCOPE
MODEL 78-4500
1. Rack & Pinion Focusing System
2. Reflector Body
5. Dobsonian Base (Azimuth Bearing)
6. Primary Mirror
3. Altitude Bearing
7. Finderscope
4. Dobsonian Side Panel
8. 1.25” Format Eyepiece
Never Look Directly At The Sun With Your Telescope
Permanent Damage To Your Eyes May Occur
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TELESCOPE USE
SELECTING AN EYEPIECE:
1. You should always start viewing with the lowest power eyepiece, which in this case is the 20
mm lens. Note: the base power of each eyepiece is determined by the focal length of the
telescope objective element, which for this model is 900 mm. A formula can be used to
determine the power of each eyepiece: telescope OBJECTIVE mirror focal length
EYEPIECE focal length = MAGNIFICATION (e.g. Using the 20 mm lens, the calculation
would look like this: 900 mm ¸ 20mm = 45x or 45 power.)
2. Included with this telescope is a Barlow lens. Barlow lenses are used to double or triple the
power of your telescope. Place your Barlow between the focusing tube and the eyepiece.
Using the example above, your 3x Barlow lens would give you a total power of 81x or 81
power. (27 x 3 = 81x or 81 power)
3. Other accessories available include a 9mm eyepiece (model #78-0101) and a standard camera
adapter (model #78-0104) for photographing the night sky.
FOCUSING TELESCOPE:
1. After inserting the eyepiece, aim the main telescope tube at a land-based target at least 200
yards away (e.g. A telephone pole or building). Fully extend focusing tube by turning Rack &
Pinion Focusing Mechanism (1)
2. While looking through selected eyepiece (in this case the 20 mm), slowly retract focusing
tube by turning Rack & Pinion Focusing Mechanism (1) until object comes into focus.
ALIGNING FINDERSCOPE:
1. Look through low-power 1.25" format eyepiece (8) and establish a well-defined target (see
focusing telescope section).
2. Looking through Finderscope (7), alternate tightening each Finderscope Adjustment Screw
surrounding the Finderscope (7) in the Finderscope Mount until crosshairs of Finderscope (7)
are precisely centered on the same object already centered in Main Telescope Tube's field of
view as seen through the 1.25" Format Eyepiece (8).
3. Now, objects located first with the Finderscope (7) will be centered in the field of view of the
main telescope as seen through the 1.25" Format Eyepiece (8).
Enjoying Your New Telescope
1. First determine your targeted object. Any bright object in the night sky is a good starting
point. One of the favorite starting points in astronomy is the moon. This is an object sure to
please any budding astronomer or experienced veteran. When you have developed
proficiency at this level, other objects become good targets. Saturn, Mars, Jupiter, and Venus
are good second steps to take.
2. The first thing you need to do after assembling the telescope as planned is center the desired
object in the finderscope's cross hairs. Provided you did a reasonable job aligning the
finderscope, a quick look through the main telescope tube at low power should reveal the
same image. With the lowest power eyepiece (the one with the largest number printed on it)
you should be able to focus the same image that you saw through the finderscope. Avoid the
temptation to move directly to the highest power. The low power eyepiece will give you a
wider field of view, and brighter image--thus making it very easy to find your target object.
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At this point with a focused image in both scopes, you've passed the first obstacle. If you
don't see an image after attempting to focus it in, you might consider aligning your
finderscope again. Once you pass this step, you'll will enjoy the time spent ensuring a good
alignment. Every object you center in the finderscope will be easily found in the main
telescope tube, which is important for continuing your exploration of the night sky.
3. The low power eyepieces are perfect for viewing the full moon, planets, star clusters, nebulae,
and even constellations. These should build your foundation. However, for more detail, try
bumping up in magnification to higher power eyepieces on some of these objects. During
calm and crisp nights, the light/dark separation line on the moon (called the "Terminator") is
marvelous at high power. You can see mountains, ridges and craters jump out at you due to
the highlights.
Similarly, you can move up to higher magnifications on the planets and
nebulae. Star clusters and stars are best viewed through the low power no matter what.
4. The recurring astronomical theater we call the night sky is an ever-changing billboard. In
other words, not the same movie plays all the time. Rather, the positions of the stars change
not only hourly as they seem to rise and set, but also throughout the year. As the earth orbits
the sun our perspective on the stars changes on a yearly cycle about that orbit. The reason
the sky seems to move daily just as the sun and the moon "move" across our sky, is that the
earth is rotating about its axis. As a result you may notice that after a few minutes or a few
seconds depending on what power you are viewing at, the objects in your telescope will
move. At higher magnifications especially, you will notice that the moon or Jupiter will
"race" right out of the field of view. To compensate, just move the fine adjustment controls
on your telescope to "track" it in the necessary path.
Helpful Hints
1. Your telescope is a very sensitive instrument. For best results and fewer vibrations set your
telescope up on a level location on the ground rather than your concrete driveway or your
wooden deck. This will provide a more stable foundation for viewing, especially if you've
drawn a crowd with your new telescope.
2. If possible view from a location that has relatively few lights. This will allow you to see
much fainter objects. You'd be surprised how much more you'll see from your local lake or
park when compared to a backyard in the city.
3. Using your telescope out a window is NEVER recommended.
4. View objects that are high in the sky if possible. Waiting until the object rises well above the
horizon will provide a brighter and crisper image. Objects on the horizon are viewed
through several layers of earth's atmosphere. Ever wonder why the moon appears orange as
it sets on the horizon. It's because you are looking through a considerable more amount of
atmosphere than you would directly overhead. (Note: If objects high in the sky are distorted
or wavy, you are probably viewing on a very humid night.) During nights of unstable
atmosphere, viewing through a telescope can be frustrating if not impossible. Astronomers
refer to crisp, clear nights as nights of "good seeing."
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Where do I start?
Your Bushnell telescope can bring the wonders of the universe to your eye. While this manual is
intended to assist you in the set-up and basic use of this instrument, it does not cover everything
you might like to know about astronomy. The first thing you need to do is get a very simple star
chart and a flashlight with a red bulb or red cellophane over the end. For objects other than stars
and constellations, a basic guide to astronomy is a must. Some recommended sources appear on
suggested viewing. But, some of the standbys that you can see are:
The Moon--a wonderful view of our lunar neighbor can be enjoyed with any magnification. Try
viewing at different phases of the moon. Lunar highlands, lunar maria (lowlands called "seas"
for their dark coloration), craters, ridges and mountains will astound you.
Saturn--even at the lowest power you should be able to see Saturn's rings and moons. This is one
of the most satisfying objects in the sky to see simply because it looks like it does in pictures.
Imagine seeing what you've seen in textbooks or NASA images from your backyard!
Jupiter--the largest planet in our solar system is spectacular. Most noted features are its dark
stripes or bands both above and below its equator. These are the north and south equatorial
belts. Also interesting are Jupiter's four major moons. Pay close attention to their positions from
night to night. They appear to be lined up on either side of Jupiter.
Mars--The Great Red Planet appears as a reddish-orange disk. Look at different times of the year
and try to catch a glimpse of the white polar ice caps.
Venus--just like the moon, Venus changed phases from month to month. Some views of brilliant
Venus appear as if you were looking at a distant crescent moon.
Nebulae--The Great Orion Nebula is a very well known night sky object. This and many others
are brought to you by this telescope.
Star Clusters--View millions of stars densely packed in a cluster that resembles a ball.
Galaxies--One of the greatest and most interesting galaxies is our neighbor the Andromeda
Galaxy. Enjoy this and many others. Much, much, more!
ANSWERS TO COMMONLY ASKED QUESTIONS
1. The image I see in the telescope is upside down and
reversed from right to left ?
·
An upside-down and reversed image is a
common characteristic of most astronomical
telescopes. Since telescopes are used for
astronomical viewing orientation is not important.
The image in the finderscope will also be reversed.
2. How do I determine the power my telescope ?
·
The power of your telescope can be determine
by dividing the focal length of the objective lens by
the focal length of the eyepiece. The eyepiece focal
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length is the number printed on the eyepiece. (For
example: 900 ¸ 20 = 45X)
3. Where do I find the Telescope Focal Length
·
The telescope focal length is the same focal
length as the objective focal length. For this
telescope it is 900mm. Telescope focal lengths
range from 600mm to 1200mm on Bausch & Lomb
and Bushnell telescopes.
4. What can I see with my telescope ?
·
Telescopes with power ranging from 25X to
50X can be used to view Star Clusters and Nebulae.
90X to 120X telescope can view galaxies. Most
planets can be seen at any magnification.
5. What do the numbers on the eyepiece mean ?
·
The numbers on the eyepiece represents the
“focal Length” of the eyepiece.
TROUBLESHOOTING GUIDE
If after you have set-up your new telescope you are unable to see any objects, use this Quick
Reference guide to help you to understand the cause of the problem and quickly determine a remedy
1. I’ve completed the set-up yet I cannot see anything
·
·
·
Check to see if objective lens cover and all
other lens covers have been removed.
Try to view an object that is 200 or more
yards away.
If there is more than one eyepiece included
with the telescope, use the lowest power
(highest number) eyepiece to begin viewing.
·
Use the Rack & Pinion Focusing Mechanism to
bring the object you are trying to view into
focus
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Telescope LIFETIME LIMITED WARRANTY
Your telescope is warranted to be free of defects in materials and workmanship for the lifetime
of the original owner. The Lifetime Limited Warranty is an expression of our confidence in the
materials and mechanical workmanship of our products and is your assurance of a lifetime of
dependable service.
If your telescope contains electrical components the electronic components are warranted to be
free of defects in materials and workmanship for one year after the date of purchase.
In the event of a defect under this warranty, we will, at our option, repair or replace the
product, provided that you return the product postage prepaid. This warranty does not cover
damages caused by misuse or improper handling, installation or maintenance of the product.
Any return made under this warranty must be accompanied by the items listed below:
1) A check in the amount of $15.00 to cover the cost of handling
2) Name and address for product return
3) An explanation of the defect
4) Product should be well packed in a sturdy outside shipping carton to prevent
damage in transit and return postage prepaid to the address listed below:
IN U.S.A. Send To:
Bushnell * 8500 Marshall Drive * Lenexa, Kansas 66214
IN CANADA Send To:
Bushnell * 25A East Pearce Street, Unit 1 * Richmond Hill, Ontario L4B 2M9
For products purchased outside the United States and Canada please contact your local dealer
for applicable warranty information. This warranty gives you specific legal rights. You may
have other rights which vary from country to country.
©2001 Bushnell Performance Optics
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