Celestron AstroMaster Telescopes: User Manual and Observation Guide

Introduction

Congratulations on your purchase of a Celestron AstroMaster telescope! This manual covers three models on azimuthal mounts: 70mm and 90mm refractors, and a 114mm Newtonian reflector. These telescopes are made from high-quality materials for durability and reliability. AstroMaster telescopes offer significant advantages for beginner astronomers, providing excellent optical quality, compactness, and reliability for exploring the wonders of the universe. They are also suitable for terrestrial observations with standard accessories. All AstroMaster telescopes come with a 2-year warranty. For more details, visit www.celestron.ru.

Key features include:

• Glass optical components with anti-reflective coatings for sharp, high-contrast images.
• Stable azimuthal mount with a convenient handle and lock for smooth, precise aiming.
• Pre-assembled, sturdy tripod with 1.25” steel legs for quick, tool-free setup.
• The Sky Level 1 astronomy software (CD-ROM) for planetarium functions and star chart printing.
• Included accessories allow observation of celestial and terrestrial objects with correct image orientation.

Please take time to read this manual thoroughly before your first observation. It provides step-by-step setup instructions, reference materials, and tips for enjoyable observations. Your telescope is designed for years of use, but safety precautions must be followed.

⚠️ WARNING:

• NEVER look at the Sun directly or through the telescope (without a proper solar filter). This can cause instant and irreversible blindness.
• NEVER use the telescope to project an image of the Sun onto any surface. Internal heat can damage the telescope and accessories.
• Do not use solar eyepiece filters or Herschel wedges. Internal heat can crack optical elements and allow direct sunlight into the observer's eye.
• Never leave the telescope unattended with children or individuals unfamiliar with its operation.

Telescope Identification and Components

The AstroMaster series includes refractors and Newtonian reflectors. The diagrams below illustrate the main components.

Assembly Instructions

This section details the telescope assembly process. It is recommended to perform the initial assembly indoors for convenience.

Tripod Assembly

1. Unpack the tripod (see Figure 2-1). It comes pre-assembled.
2. Set the tripod upright and extend the legs to their full length. Gently press down on the spreader bar (Figure 2-2). The upper part is the head.
3. Attach the accessory tray (Figure 2-3) to the spreader bar (center of Figure 2-2).
4. Align the hole in the accessory tray (flat side down) with the center of the spreader bar and press down gently (Figure 2-4). The tray's tabs should align as shown in Figure 2-4.
5. Rotate the tray to align its tabs with the spreader bar's slots and secure them (Figure 2-5). The tripod is now fully assembled (Figure 2-6).
6. Extend the tripod legs to the desired height for the mount. Minimum height is 61 cm, maximum is 104 cm. Loosen the leg lock screws (Figure 2-7), extend the legs, and retighten the screws. A fully extended tripod is shown in Figure 2-8.
7. Maximum stability and rigidity are achieved at the minimum leg height.

Figures 2-1 to 2-8 illustrate tripod assembly steps.

Mounting the Optical Tube

The optical tube attaches to the mount via a dovetail plate on the tube (or rings for 114AZ) and a dovetail bracket on the mount (Figure 2-11). Ensure the mount's locking screws are fully tightened before attaching the tube. Remove any protective packaging from the optical tube. Position the mount's dovetail bracket horizontally (Figure 2-10) to prevent the mount from rotating under the tube's weight. Remove the lens cap.

1. Loosen the main locking screw and the safety screw on the mount (near the bracket) so they do not obstruct the dovetail slot (Figure 2-11).
2. Insert the dovetail plate (attached to the tube or rings) into the open slot and slide it fully in (Figure 2-12). Tighten the main locking screw on the mount. Tighten the safety screw until it touches the dovetail plate.

⚠️ CAUTION: Never loosen the telescope or mount locking screws, except for the aiming control knobs.

Figures 2-9, 2-10, 2-11, and 2-12 show mount controls and tube mounting.

Aiming the Telescope

The azimuthal mount allows easy aiming in any direction. Vertical (altitude) movement is controlled by the aiming handle with a lock (Figure 2-10). Horizontal (azimuth) movement is controlled by the azimuth lock (Figure 2-9). To aim, first loosen both locks by turning them counter-clockwise. Then, point the tube at your target and tighten both locks by turning them clockwise.

Installing Diagonal Prism and Eyepieces

The diagonal prism redirects light at a 90-degree angle, allowing for more comfortable viewing. For refractors, it also provides an erect, non-reversed image, suitable for terrestrial viewing. The prism can be rotated for optimal positioning.

For Refractors:

1. Insert the diagonal prism's adapter sleeve into the refractor's focuser (Figure 2-13). Loosen the focuser's set screws beforehand to ensure they don't protrude into the focuser tube. Remove the adapter cap.
2. Insert the eyepiece into the diagonal prism's adapter and secure it with the set screw. Ensure the prism's set screw is not protruding into the eyepiece opening.
3. To change eyepieces, repeat step 2.

For Newtonian Reflectors:

Eyepieces provide magnification. Without an eyepiece, the telescope cannot be used for visual observation. Eyepieces are categorized by focal length; longer focal lengths yield lower magnification. For most observations, medium magnifications are used. In Newtonian reflectors, the eyepiece installs directly into the focuser.

1. Ensure the focuser's set screws are not protruding into the tube. Insert the eyepiece into the focuser tube (remove the focuser cap) and secure with the set screws (Figure 2-14).
2. The 20mm eyepiece provides an erect image, suitable for terrestrial viewing.
3. To change eyepieces, follow the same procedure.

Figures 2-13 and 2-14 show accessory installation.

Telescope Optics Explained

Telescopes gather light and form images. Refractors use lenses, while reflectors use mirrors.

Refractors: Early refractors used a single lens, but this caused chromatic aberration (color fringing). Modern achromatic refractors use two lenses to correct this, bringing different colors to a common focus. The AstroMaster refractors use an erecting prism for an upright, correctly oriented image.

Newtonian Reflectors: These use a concave primary mirror at the base of the tube. Light reflects off this mirror and focuses near the front. A secondary diagonal mirror redirects the light to the eyepiece, located on the side. Newtonians are often more affordable for their aperture size, gathering more light. However, the primary mirror is exposed to dust, and periodic collimation (alignment of optical elements) is required.

Figure 3-1 illustrates the light path in a refractor. Figure 3-2 illustrates the light path in a Newtonian reflector.

Image Orientation

Image orientation depends on the telescope's optical design and accessories. Refractors with a diagonal prism provide an erect, non-reversed image. Without the prism, the image is both reversed and inverted. Newtonian reflectors produce an inverted, but not reversed, image. The orientation can also be affected by the eyepiece's position relative to the ground.

Figure 3-3 shows different image orientations: Erect (refractor with prism), Reversed (refractor with diagonal mirror), and Inverted (refractor without prism or Newtonian).

Focusing

Turn the focuser knob to achieve a sharp image. Turning it away from you (clockwise) focuses on more distant objects. Turning it towards you (counter-clockwise) focuses on closer objects.

Note: If you wear glasses or contact lenses, you may remove them for viewing. However, keep them on for photography. If you have astigmatism, always wear corrective lenses.

Star Pointer Finder Scope Adjustment

The Star Pointer finder scope helps quickly locate celestial objects. It projects a red dot onto a glass plate, visible against the night sky. Align the red dot with the target object. The finder is powered by a CR1620 lithium battery (3V). It requires collimation to align its optical axis with the telescope's. This is best done at night.

Adjustment Steps:

1. Turn on the LED power switch (Figure 3-4).
2. Point the telescope at a bright star or planet. Center it in the eyepiece.
3. View the star through the finder with both eyes. If the red dot aligns with the star, the finder is collimated. If not, note the direction the dot is off.
4. Without moving the telescope, use the adjustment screws on the finder body (Figure 3-5) to align the red dot with the star.
5. The finder is now adjusted.

Note: Always turn off the finder's power when not in use to conserve battery life. The finder comes with a battery installed; if not, open the battery compartment (Figure 3-4) and insert a CR1620 battery with the '+' symbol facing out.

The finder can also be used for terrestrial targets, though the red dot is less visible in daylight.

Figures 3-4 and 3-5 show the Star Pointer finder scope and its adjustment.

Magnification

Magnification is changed by using different eyepieces. The formula is:

Magnification (x) = Telescope Objective Focal Length (mm) / Eyepiece Focal Length (mm)

Example: For an AstroMaster 70AZ with a 900mm objective and a 20mm eyepiece, magnification is 900mm / 20mm = 45x.

Each telescope has a maximum useful magnification, typically 2.4 times its aperture in millimeters (e.g., 70mm * 2.4 = 168x for the 70AZ). For most observations, magnifications between 0.8x and 1.4x the aperture are recommended (56x to 98x for the 70AZ). Higher magnifications are best for the Moon and planets under stable conditions.

Field of View

Field of view (FOV) helps in locating objects and estimating their angular size. The formula is:

Telescope FOV (degrees) = Eyepiece FOV (degrees) / Telescope Magnification (x)

Example: With a 50° eyepiece FOV and 45x magnification, the telescope FOV is 50° / 45x = 1.1°.

To convert to linear field of view at 1000m: 1.1° * 17.45 = 19.2 meters.

General Observation Recommendations

Follow these tips to avoid common beginner mistakes:

• Do not observe through windows. Window glass distorts images.
• Avoid observing objects near heat sources like asphalt parking lots on hot days or buildings with heating systems.
• Humidity, haze, or fog can reduce detail visibility.
• If you wear glasses, you can usually remove them for eyepiece viewing, but keep them on for photography. For astigmatism, always wear corrective lenses.

Astronomy Basics

Celestial Coordinate System

Astronomers use a celestial coordinate system similar to Earth's, with poles, equator, declination (like latitude), and right ascension (like longitude).

The celestial equator divides the sky into northern and southern hemispheres. Declination is measured in degrees north (+) or south (-) of the celestial equator. Right ascension lines run from pole to pole, spaced 15 degrees apart, measured in hours. The zero point is in the constellation Pisces.

Figure 4-1 shows the celestial sphere with Declination (DEC) and Right Ascension (RA) lines.

Apparent Star Movement

The apparent movement of stars is due to Earth's rotation. Stars trace circles around the celestial poles. Stars near the celestial equator move in the largest circles, rising in the east and setting in the west. Stars closer to the celestial pole appear to move in smaller circles. Circumpolar stars never set.

Diagrams illustrate how stars appear to move in circles around the celestial poles, with different paths depending on their position relative to the equator.

Astronomical Observations

This section provides guidance for observing objects in the Solar System and deep-sky objects.

Observing the Moon ?

Full moon offers bright illumination but can obscure surface details due to long shadows. First and last quarter phases are better for observing lunar features. Use higher magnification eyepieces for detailed views.

Tip: Use yellow filters for contrast enhancement, and neutral or polarizing filters to reduce glare.

Observing Planets ?

You can observe Mercury, Venus (phases), Mars (polar caps), Jupiter (cloud bands, Great Red Spot, moons), and Saturn (rings). Atmospheric conditions significantly affect planet viewing. Planets low on the horizon or near heat sources are harder to observe.

Tips: Use colored eyepiece filters to enhance contrast.

Observing the Sun ☀️

⚠️ EXTREME CAUTION REQUIRED: Always use a certified solar filter attached to the front of the telescope (full aperture). Never look at the Sun without one. Observe during early morning or late evening when atmospheric conditions are more stable.

To aim without looking through the eyepiece, align the telescope's shadow to be minimal.

Deep-Sky Objects ?

Deep-sky objects (galaxies, nebulae, star clusters) are best viewed in dark skies away from light pollution. Low to medium magnifications are usually sufficient. Due to low surface brightness, they appear gray to the eye, even though long-exposure photographs capture color.

Finding Deep-Sky Objects

A common method is "star-hopping," moving from bright stars to fainter ones. Knowing your telescope's field of view is crucial.

Example: Finding the Andromeda Galaxy (M31)

1. Locate the constellation Pegasus (the Great Square).
2. Start from Alpha Andromedae.
3. Move about 7° northeast to find Delta and Pi Andromedae, which are about 3° apart.
4. Move another 8° northeast to find Beta and Mu Andromedae, also about 3° apart.
5. Move 3° northeast again to find the Andromeda Galaxy (M31).

Figure 5-1 shows the star field for finding M31.

Example: Finding the Ring Nebula (M57)

1. Locate the constellation Lyra, recognizable by its parallelogram shape, near the bright star Vega.
2. From Vega, look southeast for the parallelogram of stars.
3. Identify the two southernmost stars of the parallelogram: Beta and Gamma Lyrae.
4. Point the telescope midway between these two stars.
5. Move about 0.5° towards Beta Lyrae, along the line between the two stars.
6. Look through the telescope; M57 should be visible.

Tip: M57 is faint. Use averted vision (look slightly away from the object) and allow at least 20 minutes for your eyes to dark-adapt. Use a red flashlight for charts.

Figure 5-2 shows the star field for finding M57.

Seeing Conditions

Observation quality depends on sky brightness, atmospheric transparency, and atmospheric seeing (stability).

• Atmospheric Transparency: Affected by clouds, humidity, and dust.
• Sky Brightness: Moonlight, airglow, and artificial light pollution reduce contrast, especially for faint deep-sky objects. Dark, moonless nights away from cities are best.
• Atmospheric Seeing: Air turbulence distorts light, causing images to shimmer or blur. Stable air provides sharper details.

Figure 5-3 illustrates how seeing conditions affect the appearance of a star (blurry vs. sharp).

Astrophotography

While designed for visual use, AstroMaster telescopes can be used for photography.

Methods:

• Afocal Projection: Use a digital camera with a MicroStage adapter to hold the camera steady over the eyepiece.
• Prime Focus: Remove the camera's lens and attach it to the telescope using a T-ring and T-adapter. The telescope acts as the camera's lens.

Short Exposures: Suitable for the Moon and bright planets. For longer exposures, an equatorial or computerized mount is recommended.

Specialized Cameras: Celestron's NexImage cameras are designed for planetary and lunar imaging.

Deep-Sky Imaging: Requires specialized, high-sensitivity CCD cameras.

Terrestrial Photography: The telescope can function as a telephoto lens. Experiment with focus and exposure.

Maintenance and Care

Telescopes require minimal maintenance.

Cleaning Optics ?

Dust on lenses or mirrors should be removed gently with a soft brush or compressed air. For stubborn dirt, use a specialized optical cleaning solution and lint-free wipes. Apply solution to the wipe, not directly to the optics. Clean from the center outwards in a single stroke; avoid circular motions.

DIY Cleaning Solution: Mix 6 parts isopropyl alcohol with 4 parts distilled water. A drop of dish soap in 1 liter of water can also be used.

Dew: Use a hairdryer on a low setting or allow moisture to evaporate naturally. If dew forms inside the tube, remove accessories and point the tube downwards in a dust-free area.

Protection: Always cover optical elements when not in use to prevent dust accumulation.

Newtonian Collimation

Collimation aligns optical elements for optimal image quality. Poor collimation causes aberrations.

Primary Mirror Collimation: Locate the three sets of adjustment screws at the rear of the tube. Loosen the small locking screws, then adjust the larger collimation screws (1/8 to 1/2 turn at a time) until the secondary mirror's reflection is centered in the primary mirror's reflection. Look through the focuser. You should see concentric images.

Secondary Mirror Collimation: Adjust the secondary mirror's tilt using its screws to center the primary mirror's reflection within the secondary mirror's reflection. Use collimation aids (collimation cap or eyepiece) for easier adjustment.

Diagrams show Newtonian collimation steps and alignment targets.

Star Collimation

This final step ensures the highest image quality. After daytime collimation, fine-tune using a star.

Use a high-magnification eyepiece or a Barlow lens. Aim at a bright star (Polaris is ideal). The star should appear as a sharp point surrounded by diffraction rings. If the rings are uneven or distorted, adjust the primary mirror collimation screws.

Tip: Collimation is often easier with two people: one observes and guides the other on screw adjustments. Ensure locking screws are tightened afterward.

Figures 7-1 and 7-2 show adjustment screws and diffraction patterns indicating collimation status. Figure 7-3 shows a well-collimated star's diffraction pattern.

Additional Accessories

Enhance your telescope's capabilities with Celestron accessories. Available items include:

• Omni Plossl Eyepieces (various focal lengths)
• Omni Barlow Lens (doubles magnification)
• Minus V Filter (reduces chromatic aberration in refractors)
• Lunar Filter (reduces Moon's brightness)
• UHC/LPR Filter (reduces light pollution)
• Solar Full Aperture Filter (for safe Sun viewing)
• Red LED Flashlight (preserves night vision)
• Universal Camera Adapter (for digital cameras)
• Universal T-Adapter (for SLR cameras)
• Collimation Eyepiece (for Newtonian collimation)

A full range of accessories can be found at www.celestron.ru.

Technical Specifications

Note: Technical specifications are subject to change without prior notice.

Contact Information

Celestron
5 Columbia Street
Torrance, CA 90503 U.S.A.
Tel: (310) 328-9560
Fax: (310) 212-5835
Website: www.celestron.com
Copyright 2012 Celestron. All rights reserved.

Exclusive Distributor in Russia:
Skymart Company
1905 Goda St., Moscow
Tel: +7 499 253-54-78, 790-00-31
www.celestron.ru, www.skymart.ru

(Product appearance and specifications may change without prior notice.)