Celestron 21035 Le manuel du propriétaire

INSTRUCTION MANUAL

Models #21035 (70), #21038 (50)

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CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SOLAR WARNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

WHAT’S IN THE BOX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ASSEMBLING YOUR TELESCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Setting up the Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Attaching the Telescope Tube to the Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Moving the Travel Scope Manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Installing the Diagonal & Eyepiece . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Installing the Finderscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Aligning the Finderscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

TELESCOPE BASICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Focusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Calculating Magniﬁcation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Installing & Using the Barlow Lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Determining Field of View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

General Observing Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

ASTRONOMY BASICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

The Celestial Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Motion of the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

CELESTIAL OBSERVING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Observing the Moon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Observing the Planets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Observing the Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Observing Deep-Sky Objects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Seeing Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

TELESCOPE MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Care and Cleaning of the Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

TECHNICAL SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

CELESTRON TWO YEAR LIMITED WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

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Congratulations on your purchase of a Celestron Travel Scope. The Travel Scope is made of the highest quality materials

to ensure stability and durability. All this adds up to a telescope that gives you a lifetime of pleasure with a minimal amount

of maintenance.

This telescope was designed with traveling in mind offering exceptional value. The Travel Scope features a compact and

portable design with ample optical performance. Your Travel Scope is ideal for terrestrial as well as very casual astronomical

observation.

The Travel Scope carries a two year limited warranty. For details see our website at www.celestron.com

Some of the standard features of the Travel Scope include:

• Coated glass optical elements for clear, crisp images.

• Erect image diagonal so that your views are correctly oriented.

• Smooth functioning altazimuth mount with easy pointing to located objects.

• Preassembled aluminum full size photographic tripod ensures a stable platform.

• Quick and easy no-tool set up.

• The telescope and tripod ﬁt inside the standard backpack for easy traveling.

Take time to read through this manual before embarking on your journey through the Universe. It may take a few observing

sessions to become familiar with your telescope, so you should keep this manual handy until you have fully mastered your

telescope’s operation. The manual gives detailed information regarding each step as well as needed reference material and

helpful hints to make your observing experience simple and pleasurable as possible.

Your telescope is designed to give you years of fun and rewarding observations. However, there are a few things to consider

before using your telescope that will ensure your safety and protect your equipment.

INTRODUCTION

• Never look directly at the Sun with the naked eye or with a telescope unless you have the proper solar ﬁlter. Permanent and

irreversible eye damage may result.

• Never use your telescope to project an image of the Sun onto any surface. Internal heat build-up can damage the

telescope and any accessories attached to it.

• Never use an eyepiece solar ﬁlter or a Herschel wedge. Internal heat build-up inside the telescope can cause these devices

to crack or break, allowing unﬁltered sunlight to pass through to the eye.

• Do not leave the telescope unsupervised, either when children are present or adults unfamiliar with the correct operating

procedures of your telescope are present.

SOLAR WARNING

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We recommend saving your telescope box so it can be used to store the telescope when it is not in use. Unpack the box

carefully as some parts are small. Use the parts list below to verify that all parts and accessories are present.

PARTS LIST

WHAT’S IN THE BOX

ASSEMBLING YOUR TELESCOPE

This section covers the assembly instructions for your Travel

Scope. Your telescope should be set up indoor the ﬁrst time so

that it is easy to identify the various parts and familiarize yourself

with the correct assembly procedure before attempting it outdoor.

The Travel Scope 70 comes in one box. The pieces in the box

are – telescope optical tube, tripod, erect image diagonal, 20 mm

eyepiece, 10mm eyepiece, 5x24 ﬁnderscope with bracket (all packed

in the travel backpack) and a bonus Astronomy software download.

The Travel Scope 50 comes in one box. All items the same as

above except it has a 2x20 ﬁnderscope and 8 mm eyepiece

(instead of 10 mm). In addition, the Travel Scope 50 includes a 3x

Barlow Lens – 1.25”.

2

1

1. Objective Lens

2. Telescope Optical Tube

3. Tripod Head Platform

4. Azimuth Locking Knob

5. Central Column Locking Knob

6. Tripod

7. Finderscope

8. Erect Image Diagonal

9. Eyepiece

10. Focus Knob

11. Pan Handle

7

3

4

6

8

9

10

11

5

Fig. 2

Fig. 1 Travel Scope 70 (Similar to Travel Scope 50)

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SETTING UP THE TRIPOD

1. The tripod comes preassembled so that the set up is very easy.

2. Stand the tripod upright and pull the tripod legs outward until

each leg is fully extended (Figure 3).

3.

You can raise the tripod legs to the height you desire. At the

lowest level the height is about 16” (41 cm) and extends to

about 49” (125 cm).

4. To raise the height of the tripod, you unlock the tripod leg lock

clamps at the bottom of each tripod leg (Figure 4) by opening the

clamp for each section by pulling outward. Once a clamp is

unlocked, then pull the tripod leg out as far as it will go and then

close the leg lock to secure it. Continue doing this for each

tripod leg and each section to raise the height to the level you

desire. A fully extended tripod looks similar to the image in Figure

5. With all the legs raised up on all sections, the height will be

about 42” (107 cm).

5. If you want to raise the tripod height up further you must use the

central column locking knob which is the knob located at the

bottom left in Figure 6. Turn the locking knob counterclockwise

until loose. Then, pull up on the head of the tripod and the

central column will move up. Continue pulling to the height you

desire and then tighten the locking knob. When the central

column is raised up as far as it will go, then the maximum height

possible is achieved – 49” (125 cm).

Fig. 3

Fig. 4

Fig. 5

Fig. 6

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ATTACHING THE TELESCOPE TUBE TO THE TRIPOD

The telescope optical tube attaches to the tripod by using the mounting bracket on the bottom of the optical tube and the

mounting platform of the tripod. Before starting make sure all of the knobs on the tripod are locked.

1. Remove the protective paper covering the optical tube.

2. Loosen the top right knob (ﬁgure 7) by turning it counterclockwise.

This allows you to tilt the tripod platform up 90° as shown in

ﬁgure 8. After tilting the platform up, tighten the knob to secure

it in place.

3. Figure 9 shows the bottom of the optical tube, the tripod

platform, and where they will attach to each other.

4. Under the center of the tripod platform, you will see a knob

(ﬁgure 9) that contains a ¼ x 20 screw to attach the platform to

the telescope optical tube.

5. You can put the ¼ x 20 screw into the threaded holes of the

Travel Scope 70 (it doesn’t matter which one you use) in the

mounting bracket of the telescope optical tube whereas the

Travel Scope 50 has only one threaded hole. Hold the optical

tube with one hand while threading the screw clockwise until

tight with the other hand. Now the assembly will look like

Figure 10.

6. Lastly, loosen the knob for the tripod platform and lower the

platform down to the level position. Then, tighten the knob

securely.

Fig. 7

Fig. 8

Fig. 9

Fig. 10

MOVING THE TRAVEL SCOPE MANUALLY

The Travel Scope is easy to move wherever you want to point it. The up and down (altitude) is controlled by the Pan Handle

Control Knob (ﬁgure 1). The side-to-side (azimuth) is controlled by the Azimuth Locking Knob (top left knob in Figure 7). Both

knobs are loosened when turned counterclockwise and tightened when turned clockwise. When both knobs are loose you

can ﬁnd your objects easily (through the ﬁnderscope which is discussed shortly) and then lock the controls.

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INSTALLING THE DIAGONAL AND EYEPIECE

The diagonal is a prism that diverts the light at a right angle to the light path of the telescope. This allows you to observe

in a position that is more comfortable than if you had to look straight through. The Travel Scope diagonal is an erect image

model that corrects the image to be right side up and oriented correctly left-to-right which is much easier to use for terrestrial

observing. Also, the diagonal can be rotated to any position which is most favorable for you. To install the diagonal and

eyepiece:

1. Make sure the two thumbscrews on the rear of the telescope

tube do not protrude into the opening before installation, the

plug up cap is removed from the opening at the rear of the

telescope tube, and the caps are removed from the barrels on

the diagonal. Insert the small barrel of the diagonal all the way

into the rear opening of the telescope tube (Figure 11). Then

tighten the two thumbscrews.

2. Put the chrome barrel end of one of the eyepieces into the

diagonal and tighten the thumb screw. When doing this make

sure the thumbscrew is not protruding into the diagonal before

inserting the eyepiece.

3.

The eyepieces can be changed to other focal lengths by

reversing the procedure in step 2 above.

Fig. 11

INSTALLING THE FINDERSCOPE (TRAVEL SCOPE 70 ONLY)

1. Locate the ﬁnderscope (it will be mounted in the ﬁnderscope

bracket).

2. Remove the knurled nuts on the threaded posts on the

telescope tube (Figure 12).

3. Mount the ﬁnderscope bracket by placing it over the posts

protruding from the optical tube and then holding it in place

thread on the knurled nuts and tightening them down.

4. Note that the ﬁnderscope should be oriented so that the larger

diameter lens is facing toward the front of the telescope tube.

5. Remove the lens caps from both ends of the ﬁnderscope.

ALIGNING THE FINDERSCOPE

1. Locate a distant daytime object and center it in the low power (20 mm) eyepiece in the main telescope.

2. Look through the ﬁnderscope (the eyepiece end of the ﬁnderscope) and take notice of the position of the same object.

3. Without moving the main telescope, turn the adjustment thumbscrews (ﬁgure 12) located around the ﬁnderscope bracket

until the crosshairs of the ﬁnderscope are centered on the object chosen with the main telescope.

4. If the image through the ﬁnderscope is out of focus, rotate the eyepiece of the ﬁnderscope for a clear view.

Note: Objects viewed through a ﬁnderscope are upside down and backwards which is normal.

Fig. 12

Finderscope

Bracket

Finderscope

Eyepiece

Adjustment

Screws

Knurled

Nuts

Objective Lens

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TELESCOPE BASICS

FOCUSING

To focus your Travel Scope turn the focus knob located near the rear of the telescope (see Figure 1). Turning the

knob counterclockwise allows you to focus on an object that is farther than the one you are currently observing.

Turning the knob clockwise from you allows you to focus on an object closer than the one you are currently observing.

Note: Remove the front lens cap of the Travel Scope optical tube prior to attempting your observation.

Note: If you wear corrective lenses (speciﬁcally glasses), you may want to remove them when observing with an eyepiece

attached to the telescope. If you have astigmatism, corrective lenses should be worn at all times.

Focal length of Telescope (mm)

Magniﬁcation =

_____________________________

Focal length of Eyepiece (mm)

INSTALLING AND USING THE BARLOW LENS (TRAVEL SCOPE 50 ONLY)

Let’s say, for example, you are using the 20mm eyepiece that came with your Travel Scope 70 telescope. To determine the

magniﬁcation you divide the focal length of your telescope (the Travel Scope for this example has a focal length of 400mm)

by the focal length of the eyepiece, 20mm. Dividing 400 by 20 yields a magniﬁcation of 20x.

Although the power is variable, every telescope under average skies has a limit to the highest useful magniﬁcation. The

general rule is that 60 power can be used for every inch of aperture. For example, the Travel Scope 70 is 2.8” inches in

diameter. Multiplying 2.8 by 60 gives a maximum useful magniﬁcation of 168 power. Although this is the maximum useful

magniﬁcation, most of your observing will be done at low powers which generate brighter and sharper images.

Note on Using High Powers– Higher powers are used mainly for lunar and sometimes planetary observing where you can

greatly enlarge the image, but remember that the contrast and brightness will be very low due to the high magniﬁcation.

When using the 8mm eyepiece together with the 3x Barlow lens with the Travel Scope 50 gives extremely high power and

can be used on rare occasions – you will achieve the power but the image will be dark with low contrast because you have

magniﬁed it to the maximum possible. For the brightest images with the highest contrast levels, use lower powers.

You can purchase optional eyepieces to give you a range of powers you can observe with. Visit the Celestron website to see

what is available.

Your telescope also comes with a 3x Barlow Lens

which triples the magnifying power of each eyepiece.

However, the greatly magniﬁed images should only

be used under ideal conditions – see the Calculating

Magniﬁcation section of this manual. To use the

Barlow lens remove the diagonal and insert the

Barlow directly into the focuser tube. You then insert

an eyepiece into the Barlow lens for viewing.

Note: Start by using a low power eyepiece as it will

be easier to focus.

CALCULATING MAGNIFICATION

You can change the power of your telescope just by changing the eyepiece (ocular). To determine the magniﬁcation of your

telescope, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the

formula looks like this:

3x Barlow Lens

Fig. 13

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DETERMINING FIELD OF VIEW

Determining the ﬁeld of view is important if you want to get an idea of the angular size of the object you are observing. To

calculate the actual ﬁeld of view, divide the apparent ﬁeld of the eyepiece (supplied by the eyepiece manufacturer) by the

magniﬁcation. In equation format, the formula looks like this:

Apparent Field of of Eyepiece

True Angular Field =

________________________________

Magniﬁcation

As you can see, before determining the ﬁeld of view, you must calculate the magniﬁcation. Using the example in the previous

section, we can determine the ﬁeld of view using the same 20 mm eyepiece that is supplied standard with the Travel Scope

70. The 20 mm eyepiece has an apparent ﬁeld of view of 50°. Divide the 50° by the magniﬁcation, which is 20 power. This

yields an actual (true) ﬁeld of 2.5°.

To convert degrees to feet at 1,000 yards (which is more useful for terrestrial observing) multiply by 52.5. Multiply the

angular ﬁeld of 2.5° by 52.5. This produces a linear ﬁeld width of 131 feet at a distance of one thousand yards.

GENERAL OBSERVING HINTS

When using any optical instrument, there are a few things to remember to ensure you get the best possible image.

• Never look through window glass. Glass found in household windows is optically imperfect, and as a result, may vary in

thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your telescope. In

most cases you will not be able to achieve a truly sharp image, while in some cases you may actually see a double image.

• Never look across or over objects that are producing heat waves. This includes asphalt parking lots on hot summer days or

building rooftops.

• Hazy skies, fog, and mist can also make it difﬁcult to focus when viewing terrestrially. The amount of detail seen under these

conditions is greatly reduced.

Note: Your telescope was designed for terrestrial observation. Knowing how to use it for this purpose has been described

already as it is quite simple and straightforward. Your telescope can also be used for casual astronomical observing

which will be discussed in the next sections.

ASTRONOMY BASICS

Up to this point, this manual covered the assembly and basic operation of your telescope. However, to understand your

telescope more thoroughly, you need to know a little about the night sky. This section deals with observational astronomy in

general and includes information on the night sky.

THE CELESTIAL COORDINATE SYSTEM

To help ﬁnd objects in the sky, astronomers use a celestial coordinate system that is similar to our geographical coordinate system

here on Earth. The celestial coordinate system has poles, lines of longitude and latitude, and an equator. For the most part, these

remain ﬁxed against the background stars.

12 I ENGLISH

The celestial equator runs 360 degrees around the Earth and separates the northern celestial hemisphere from the southern.

Like the Earth’s equator, it bears a reading of zero degrees. On Earth this would be latitude. However, in the sky this is referred

to as declination, or DEC for short. Lines of declination are named for their angular distance above and below the celestial

equator. The lines are broken down into degrees, minutes of arc, and seconds of arc. Declination readings south of the equator

carry a minus sign (-) in front of the coordinate and those north of the celestial equator are either blank (i.e., no designation) or

preceded by a plus sign (+).

The celestial equivalent of longitude is called Right Ascension or R.A. for short. Like the Earth’s lines of longitude, they run from

pole to pole and are evenly spaced 15 degrees apart. Although the longitude lines are separated by an angular distance, they

are also a measure of time. Each line of longitude is one hour apart from the next. Since the Earth rotates once every 24 hours,

there are 24 lines total. As a result, the R.A. coordinates are marked off in units of time. It begins with an arbitrary point in the

constellation of Pisces designated as 0 hours, 0 minutes, 0 seconds. All other points are designated by how far (i.e., how long)

they lag behind this coordinate after it passes overhead moving toward the west.

MOTION OF THE STARS

The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun moving as

early astronomers thought, but the result of the Earth’s rotation. The Earth’s rotation also causes the stars to do the same, scribing

out a large circle as the Earth completes one rotation. The size of the circular path a star follows depends on where it is in the sky.

Stars near the celestial equator form the largest circles rising in the east and setting in the west. Moving toward the north celestial

pole, the point around which the stars in the northern hemisphere appear to rotate, these circles become smaller. Stars in the

mid-celestial latitudes rise in the northeast and set in the northwest. Stars at high celestial latitudes are always above the horizon,

and are said to be circumpolar because they never rise and never set. You will never see the stars complete one circle because

the sunlight during the day washes out the starlight. However, part of this circular motion of stars in this region of the sky can be

seen by setting up a camera on a tripod and opening the shutter for a couple hours. The timed exposure will reveal semicircles

that revolve around the pole. (This description of stellar motions also applies to the southern hemisphere except all stars south of

the celestial equator move around the south celestial pole.)

Stars seen near the north celestial pole Stars seen near the celestial equator Stars seen looking in the opposite direction

of the north celestial pole

Fig. 15

All stars appear to rotate around the celestial poles. However, the appearance of this motion varies depending on where you are looking in the sky. Near

the north celestial pole the stars scribe out recognizable circles centered on the pole (1). Stars near the celestial equator also follow circular paths around

the pole. But, the complete path is interrupted by the horizon. These appear to rise in the east and set in the west (2). Looking toward the opposite pole,

stars curve or arc in the opposite direction scribing a circle around the opposite pole (3).

Fig. 14

The celestial sphere seen from the

outside showing R.A. and DEC.

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CELESTIAL OBSERVING

With your telescope set up, you are ready to use it for observing. This section covers visual observing hints for solar system and

deep sky objects as well as general observing conditions which will affect your ability to observe.

OBSERVING THE MOON

With your telescope set up, you are ready to use it for observing. This section covers visual observing hints for solar system and

deep sky objects as well as general observing conditions which will affect your ability to observe.

Often, it is tempting to look at the Moon when it is full. At this time, the face

we see is fully illuminated and its light can be overpowering. In addition,

little or no contrast can be seen during this phase. One of the best times

to observe the Moon is during its partial phases (around the time of ﬁrst or

third quarter). Long shadows reveal a great amount of detail on the lunar

surface. At low power you will be able to see most of the lunar disk at

one time. Change to optional eyepieces for higher power (magniﬁcation) to

focus in on a smaller area.

Lunar Observing Hints

To increase contrast and bring out detail on the lunar surface, use optional

ﬁlters. A yellow ﬁlter works well at improving contrast while a neutral density

or polarizing ﬁlter will reduce overall surface brightness and glare.

OBSERVING THE PLANETS

Other fascinating targets include the ﬁve naked eye planets. You can see Venus go through its lunar-like phases. Mars can reveal

a host of surface detail and one, if not both, of its polar caps. You may be able to see the cloud belts of Jupiter and the great Red

Spot (if it is visible at the time you are observing). In addition, you will also

be able to see the moons of Jupiter as they orbit the giant planet. Saturn,

with its beautiful rings, is e visible at moderate power.

Planetary Observing Hints

• Remember that atmospheric conditions are usually the limiting factor on

how much planetary detail will be visible. So, avoid observing the planets

when they are low on the horizon or when they are directly over a source

of radiating heat, such as a rooftop or chimney. See the “Seeing

Conditions” section later in this section.

• To increase contrast and bring out detail on the planetary surface, try

using Celestron eyepiece ﬁlters.

OBSERVING THE SUN

Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. However, because the Sun is so

bright, special precautions must be taken when observing our star so as not to damage your eyes or your telescope.

For safe solar viewing, use a proper solar ﬁlter that reduces the intensity of the Sun’s light, making it safe to view. With a ﬁlter you

can see sunspots as they move across the solar disk and faculae, which are bright patches seen near the Sun’s edge.

• The best time to observe the Sun is in the early morning or late afternoon when the air is cooler.

• To center the Sun without looking into the eyepiece, watch the shadow of the telescope tube until it forms a circular shadow.

14 I ENGLISH

OBSERVING DEEP-SKY OBJECTS

Deep-sky objects are simply those objects outside the boundaries of our solar system. They include star clusters, planetary

nebulae, diffuse nebulae, double stars and other galaxies outside our own Milky Way. Most deep-sky objects have a large

angular size. Therefore, low-to-moderate power is all you need to see them. Visually, they are too faint to reveal any of the

color seen in long exposure photographs. Instead, they appear black and white. And, because of their low surface brightness,

they should be observed from a dark-sky location. Light pollution around large urban areas washes out most nebulae making

them difﬁcult, if not impossible, to observe. Light Pollution Reduction ﬁlters help reduce the background sky brightness, thus

increasing contrast.

Star Hopping

One convenient way to ﬁnd deep-sky objects is by star hopping. Star hopping is done by using bright stars to “guide” you to an

object. For successful star hopping, it is helpful to know the ﬁeld of view of you telescope. If you’re using the standard 20 mm

eyepiece with the Travel Scope 70, your ﬁeld of view is approximately 2.5º or so. If you know an object is 3º away from your present

location, then you just need to move a little more than one ﬁeld of view. If you’re using another eyepiece, then consult the section

on determining ﬁeld of view. Listed below are directions for locating two popular objects.

The Andromeda Galaxy (Figure 16), also known as M31, is an easy target. To ﬁnd M3:

1. Locate the constellation of Pegasus, a large square visible in the fall (in the eastern sky, moving toward the point overhead)

and winter months (overhead, moving toward the west).

2. Start at the star in the northeast corner—Alpha (α ) Andromedae.

3. Move northeast approximately 7°. There you will ﬁnd two stars of equal brightness—Delta (δ) and Pi (π) Andromeda—about

3° apart.

4. Continue in the same direction another 8°. There you will ﬁnd two stars—Beta (β) and Mu (μ) Andromedae —also about

3° apart.

5. Move 3° northwest—the same distance between the two stars—to the Andromeda galaxy.

Star hopping to the Andromeda Galaxy (M31) is a snap, since all the stars needed to do so are visible to the naked eye.

Fig. 16

Andromeda Galaxy

ENGLISH I 15

Star hopping will take some getting used to and objects that don’t have stars near them that are visible to the naked eye are

challenging. One such object is M57 (Figure 17), the famed Ring Nebula. Here’s how to ﬁnd it:

1. Find the constellation of Lyra, a small parallelogram visible in the summer and fall months. Lyra is easy to pick out because

it contains the bright star Vega.

2. Start at the star Vega—Alpha (α ) Lyrae—and move a few degrees southeast to ﬁnd the parallelogram. The four stars that

make up this geometric shape are all similar in brightness, making them easy to see.

3. Locate the two southernmost stars that make up the parallelogram—Beta (β) and Gamma (γ ) Lyra.

4. Point about halfway between these two stars.

5. Move about ½° toward Beta (β) Lyra, while remaining on a line connecting the two stars.

6. Look through the telescope and the Ring Nebula should be in your ﬁeld of view. The Ring Nebula’s angular size is quite

small and difﬁcult to see.

7. Because the Ring Nebula is rather faint, you may need to use “averted vision” to see it. “Averted vision” is a technique of

looking slightly away from the object you’re observing. So, if you are observing the Ring Nebula, center it in your ﬁeld of

view and then look off toward the side. This causes light from the object viewed to fall on the black and white sensitive

rods of your eyes, rather than your eyes color sensitive cones. (Remember that when observing faint objects, it’s important

to try to observe from a dark location, away from street and city lights. The average eye takes about 20 minutes to fully

adapt to the darkness. So always use a red-ﬁltered ﬂashlight to preserve your dark-adapted night vision).

These two examples should give you an idea of how to star hop to deep-sky objects. To use this method on other objects,

consult a star atlas, then star hop to the object of your choice using “naked eye” stars.

Fig. 17

Ring Nebula

16 I ENGLISH

SEEING CONDITIONS

Viewing conditions affect what you can see through your telescope during an observing session. Conditions include

transparency, sky illumination, and seeing. Understanding viewing conditions and the effect they have on observing will help

you get the most out of your telescope.

Transparency

Transparency is the clarity of the atmosphere which is affected by clouds, moisture, and other airborne particles. Thick cumulus

clouds are completely opaque while cirrus can be thin, allowing the light from the brightest stars through. Hazy skies absorb more

light than clear skies making fainter objects harder to see and reducing contrast on brighter objects. Aerosols ejected into the

upper atmosphere from volcanic eruptions also affect transparency. Ideal conditions are when the night sky is inky black.

Sky Illumination

General sky brightening caused by the Moon, aurorae, natural airglow, and light pollution greatly affect transparency. While not

a problem for the brighter stars and planets, bright skies reduce the contrast of extended nebulae making them difﬁcult, if not

impossible to see. To maximize your observing, limit deep sky viewing to moonless nights far from the light polluted skies found

around major urban areas. LPR ﬁlters enhance deep sky viewing from light polluted areas by blocking unwanted light while

transmitting light from certain deep sky objects. You can, on the other hand, observe planets and stars from light polluted areas

or when the Moon is out.

Seeing

Seeing conditions refers to the stability of the atmosphere and directly affects the amount of ﬁne detail seen in extended

objects. The air in our atmosphere acts as a lens which bends and distorts incoming light rays. The amount of bending depends

on air density. Varying temperature layers have different densities and, therefore, bend light differently. Light rays from the same

object arrive slightly displaced creating an imperfect or smeared image. These atmospheric disturbances vary from time-to-time

and place-to-place. The size of the air parcels compared to your aperture determines the “seeing” quality. Under good seeing

conditions, ﬁne detail is visible on the brighter planets like Jupiter and Mars, and stars are pinpoint images. Under poor seeing

conditions, images are blurred and stars appear as blobs.

The conditions described here apply to both visual and photographic observations.

Fig. 18

Seeing conditions directly affect image quality. These drawings represent a point source (i.e., star) under bad

seeing conditions (left) to excellent conditions (right). Most often, seeing conditions produce images that lie

some where between these two extremes.

ENGLISH I 17

TELESCOPE MAINTENANCE

While your telescope requires little maintenance, there are a few things to remember that will ensure your telescope

performs at its best.

CARE AND CLEANING OF THE OPTICS

Occasionally, dust and/or moisture may build up on the objective lens of your telescope. Special care should be taken when

cleaning any instrument so as not to damage the optics.

If dust has built up on the optics, remove it with a brush (made of camel’s hair) or a can of pressurized air. Spray at an angle

to the glass surface for approximately two to four seconds. Then, use an optical cleaning solution and white tissue paper to

remove any remaining debris. Apply the solution to the tissue and then apply the tissue paper to the optics. Low pressure

strokes should go from the center of the lens (or mirror) to the outer portion. Do NOT rub in circles!

You can use a commercially made lens cleaner or mix your own. A good cleaning solution is isopropyl alcohol mixed with

distilled water. The solution should be 60% isopropyl alcohol and 40% distilled water. Or, liquid dish soap diluted with water

(a couple of drops per one quart of water) can be used.

Occasionally, you may experience dew build-up on the optics of your telescope during an observing session. If you want to

continue observing, the dew must be removed, either with a hair dryer (on low setting) or by pointing the telescope at the

ground until the dew has evaporated.

If moisture condenses on the inside of the optics, remove the accessories from the telescope. Place the telescope in a dust-

free environment and point it down. This will remove the moisture from the telescope tube.

To minimize the need to clean your telescope, replace all lens covers once you have ﬁnished using it. Since the cells are NOT

sealed, the covers should be placed over the openings when not in use. This will prevent contaminants from entering the

optical tube.

Internal adjustments and cleaning should be done only by the Celestron repair department. If your telescope is in need of

internal cleaning, please call the factory for a return authorization number and price quote.

18 I ENGLISH

TECHNICAL

SPECIFICATIONS

Model # 21035

Travel Scope 70

Model # 21038

Travel Scope 50

Optical Design Refractor Refractor

Aperture 70 mm (2.8") 50 mm (2.0”)

Focal Length 400 mm 360 mm

Focal Ratio f/5.7 f/7.2

Optical Coatings Fully Coated Coated

Finderscope 5x24 2x20

Diagonal Erect Image - 45° 1.25" Erect Image .96” to 1.25” - 45°

Eyepieces 20 mm 1.25" (20x) 20 mm 1.25” (18x)

10 mm 1.25" (40x) 8 mm 1.25” (45x)

Barlow Lens – 3x 1.25” N/A Yes (60x & 135x)

Apparent Field of View 20 mm @ 50° 20 mm @ 32°

10 mm @ 50° 8 mm @ 30°

Angular Field of View 20 mm @ 2.5° 20 mm @ 1.6°

10 mm @ 1.3° 8 mm @ 0.7°

Linear Field of View --

ft/1000 yards 20 mm @ 131/44 20 mm @ 84/28

m/1000 meters 10 mm @ 67/22 8 mm @ 37/13

Near Focus w/20 mm Eyepiece 19’ (5.8 m) 15’ (4.5 m)

Mount Altazimuth (Photo Tripod) Altazimuth (Photo Tripod)

Altitude Locking Knob Yes Yes

Azimuth Locking Knob No No

Astronomy Software Download Yes Yes

Highest Useful Magniﬁcation 168x 120x

Limiting Stellar Magnitude 11.7 11.1

Resolution -- Raleigh (arc seconds) 1.98 2.66

Resolution -- Dawes Limit “ “ 1.66 2.28

Light Gathering Power 100x 51x

Optical Tube Length 17” (43 cm) 12” (30 cm)

Telescope Weight 3.3# (1.5 kg) 2.2# (1.0 kg)

Note: Speciﬁcations are subject to change without notice or obligation.

ENGLISH I 19

NOTES

www.celestron.com

2835 Columbia Street • Torrance, CA 90503 U.S.A.

Telephone: 800.421.9649

CELESTRON TWO YEAR LIMITED WARRANTY

A. Celestron warrants your telescope to be free from defects in materials and workmanship for two years. Celestron will repair or replace

such product or part thereof which, upon inspection by Celestron, is found to be defective in materials or workmanship. As a condition to

the obligation of Celestron to repair or replace such product, the product must be returned to Celestron together with proof-of-purchase

satisfactory to Celestron.

B. The Proper Return Authorization Number must be obtained from Celestron in advance of return. Call Celestron at (310) 328-9560 to receive

the number to be displayed on the outside of your shipping container.

All returns must be accompanied by a written statement setting forth the name, address, and daytime telephone number of the owner, together

with a brief description of any claimed defects. Parts or product for which replacement is made shall become the property of Celestron.

The customer shall be responsible for all costs of transportation and insurance, both to and from the factory of Celestron, and shall be required

to prepay such costs.

Celestron shall use reasonable efforts to repair or replace any telescope covered by this warranty within thirty days of receipt. In the event repair

or replacement shall require more than thirty days, Celestron shall notify the customer accordingly. Celestron reserves the right to replace any

product which has been discontinued from its product line with a new product of comparable value and function.

This warranty shall be void and of no force of effect in the event a covered product has been modiﬁed in design or function, or subjected

to abuse, misuse, mishandling or unauthorized repair. Further, product malfunction or deterioration due to normal wear is not covered by

this warranty.

CELESTRON DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WHETHER OF MERCHANTABILITY OF FITNESS FOR A PARTICULAR USE, EXCEPT AS EXPRESSLY SET FORTH HEREIN. THE SOLE

OBLIGATION OF CELESTRON UNDER THIS LIMITED WARRANTY SHALL BE TO REPAIR OR REPLACE THE COVERED PRODUCT, IN ACCORDANCE WITH THE TERMS SET FORTH HEREIN. CELESTRON

EXPRESSLY DISCLAIMS ANY LOST PROFITS, GENERAL, SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES WHICH MAY RESULT FROM BREACH OF ANY WARRANTY, OR ARISING OUT OF THE USE

OR INABILITY TO USE ANY CELESTRON PRODUCT. ANY WARRANTIES WHICH ARE IMPLIED AND WHICH CANNOT BE DISCLAIMED SHALL BE LIMITED IN DURATION TO A TERM OF TWO YEARS

FROM THE DATE OF ORIGINAL RETAIL PURCHASE.

Some states do not allow the exclusion or limitation of incidental or consequential damages or limitation on how long an implied warranty lasts,

so the above limitations and exclusions may not apply to you.

This warranty gives you speciﬁc legal rights, and you may also have other rights which vary from state to state.

Celestron reserves the right to modify or discontinue, without prior notice to you, any model or style telescope.

If warranty problems arise, or if you need assistance in using your telescope contact: Celestron - 800.421.9649

NOTE: This warranty is valid to U.S.A. and Canadian customers who have purchased this product from an authorized Celestron dealer in the U.S.A. or Canada. Warranty outside the U.S.A. and Canada

is valid only to customers who purchased from a Celestron’s International Distributor or Authorized Celestron Dealer in the speciﬁc country. Please contact them for any warranty service.

FCC NOTE: This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device

may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause

undesired operation.

Product design and speciﬁcations are subject to change without prior notiﬁcation.

This product is designed and intended for use by those 14 years of age and older.

04-17

Printed in China

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