National Geographic 70/900 Telescope - Operating Manual

General Information

This manual provides essential safety instructions and operating procedures for the National Geographic 70/900 Telescope. Please read carefully to avoid damage or injury. Keep this manual for future reference.

Intended Use

This product is designed exclusively for private use, intended for magnified observation of natural phenomena.

General Warnings

⚠️ Risk of Blindness: Never look directly at the sun or its vicinity with this telescope. Doing so can cause blindness.

⚠️ Choking Hazard: Keep packaging materials (plastic bags, rubber bands, etc.) away from children. Children should only use the device under adult supervision.

⚠️ Fire Risk: Do not expose the telescope, especially the lenses, to direct sunlight. Concentrated light can cause fires.

⚠️ Caution: Do not disassemble the device. Contact your dealer for any defects. Do not expose the device to high temperatures.

? Privacy Protection: This device is for private use only. Respect the privacy of others; do not use it to observe private spaces.

Parts Identification

Accessories may vary depending on the model.

Telescope Components (No. 1-3)

• 1: Telescope Tube
• 2: Viewfinder Scope
• 3: Adjusting Screws (Viewfinder)
• 4: Barrel Opening
• 5: Objective Lens
• 6: Eyepiece Connection Tube
• 7: Focus Wheel
• 8: Tube Rings
• 9: Tripod Head (Mount)
• 10: Accessory Tray
• 11: Adjusting Screws (Tripod)
• 12: Fixation Bracket (Accessory Tray)
• 13: Tripod Legs
• 14: Flexible Shaft (Elevation Axis)
• 15: Flexible Shaft (Azimuth Axis)
• 16: Tripod Brace
• 17: Latitude Adjustment
• 18: Eyepieces
• 19: Diagonal Mirror
• 20: Erecting Lens

Mount Components (No. 15)

• A: Vertical Clamp
• B: Incline Plate
• C: Declination Axis
• D: Flexible Shaft (Tracking)
• E: Flexible Shaft (Declination Axis)
• F: Focus Wheel

Telescope Diagram Description (No. 1)

The main diagram shows a refractor telescope mounted on an equatorial mount. The telescope tube (1) features an objective lens (5) at the front and an eyepiece connection (6) at the rear. A viewfinder scope (2) is attached to the top of the tube. The mount (9) includes adjustment controls and flexible shafts (14, 15) for precise aiming. The tripod (13) provides a stable base with adjustable legs.

Part I - Setup

1. General/Location

Choose a suitable location with a clear view of the sky, stable footing, and ample space. Unpack all parts and verify against the diagrams.

? Note: Hand-tighten all screws to avoid overtightening.

2. Tripod Setup

The tripod legs are pre-assembled. Place the tripod upright. Carefully extend two legs to their fully open position, ensuring the entire weight rests on one leg. Then, set the tripod upright. Extend each leg to the desired length by loosening the fastening clips (No. 4, X). Tighten the clips and place the tripod on a firm, level surface.

? Tip: A small spirit level on the accessory tray (No. 10) can help ensure the tripod is level.

3. Accessory Tray Mounting

Attach the accessory tray (No. 1+3, 10) with its flat side down to the center of the tripod brace (No. 1, 16). Mount by rotating clockwise 60° (No. 5). Ensure the tray's tabs align with and secure onto the brace's fittings.

4. Telescope Tube Mounting

To mount the telescope tube (No. 1, 1), loosen the screw on the tube ring (No. 6, X) and open the ring. Place the tube centrally in the ring, close it, and tighten the screw. Position the tube assembly with the objective opening facing North and attach it to the tripod head (No. 1, 9) using the clamping screw (No. 7, X).

5. Eyepiece Installation

Your telescope includes three eyepieces (No. 1+2, 18) and a diagonal mirror (No. 1+2, 19). Remove dust caps from the eyepiece connection tube (No. 1, 6). Loosen the clamping screw (No. 8, X) on the connection tube, insert the diagonal mirror, and retighten the screw. Repeat for the 20mm eyepiece into the diagonal mirror using screw (No. 9, X). Ensure the eyepiece points vertically upward; adjust if necessary.

⚠️ Risk of Blindness: Never look directly at the sun.

6. Viewfinder Assembly and Alignment

The viewfinder scope (No. 2) and its holder are pre-assembled. Push the holder's foot into the telescope tube base (No. 10) until it clicks. Ensure the viewfinder lens faces the barrel opening (No. 1, 4). Tighten the black clamping screws (No. 1, 3) on the holder until resistance is felt.

Before observation, align the viewfinder: The viewfinder and main telescope must point identically. Use a distant, easily identifiable terrestrial object (No. 11). Center the object in the main telescope's eyepiece. Then, adjust the viewfinder using its screws (No. 1, 3) until its crosshairs match the main telescope's view (No. 11, B). Focus the viewfinder by rotating its front lens barrel (No. 10, X).

7. Protection Caps

Use protection caps (No. 12, X) for the barrel opening and eyepiece connection to prevent dust and dirt ingress. Remove them before observing.

8. Flexible Shafts

Install the flexible shafts (No. 1, 14 and 15) into the mount's holding devices (No. 13, X and Y) for precise adjustment of the declination and right ascension axes. The long shaft (No. 1, 14) mounts parallel to the tube, secured by a clamping screw. The short shaft (No. 1, 15) mounts laterally, secured similarly.

Your telescope is now ready for use.

Part II - Handling

1. Telescope Mount

The mount allows for two observation types:

• A. Azimuth: Ideal for terrestrial observation (horizontal and vertical movement).
• B. Parallactic: Ideal for celestial observation.

A. Azimuth Use:

Loosen the polar vertical clamping screw (No. 14a, X) and lower the incline plate (No. 15, B) to horizontal. Retighten the screw. Loosen the vertical clamp (No. 15, A), move the telescope to horizontal, and retighten the clamp. Movement is controlled by the flexible shafts (No. 1, 14 and 15).

B. Parallactic Use:

2. Night Use

For night observations, a dark location is crucial. Allow your eyes about 20 minutes to adjust to darkness. Position the telescope and accessories outside about 30 minutes before observing for temperature compensation. Ensure the telescope is on a stable, flat surface.

3. Alignment - Basic Siting

Loosen the polar vertical clamping screw (No. 14a, X) and roughly set the incline plate (No. 15, B) to your location's latitude. Align the tripod's 'N' mark with North; the incline plate top should also face North (No. 14b), with the latitude adjustment rod (No. 14a, Y) pointing South.

4. Setting Latitude

Determine your location's latitude from maps or the internet. Loosen the polar vertical clamping screw (No. 14a, X) and adjust the incline plate until the number on the latitude adjustment rod (No. 14a, Y) matches your latitude.

5. Final Alignment

Rotate the declination axis (No. 15, C) by 90°. Place the tube correctly in the holder and tighten the screw. The eyepiece should point down, and the objective up. Loosen the latitude adjustment screw and declination axis, then center the polar star in the eyepiece field of view (No. 17). Retighten the screws. Do not move the tripod after this alignment.

6. Tracking and Observation Positioning

Tilt the telescope body 90° (No. 15, C) and rotate it 180° until the objective lens points skyward. Tighten all clamping screws (No. 13, Y + No. 15, A) to enable tracking with the flexible shafts. Manual operation of the right ascension axis (No. 15, D) compensates for Earth's rotation, keeping objects in view. To track other objects, loosen clamps, reposition, and retighten. Fine adjustments are made with the flexible shafts (No. 1, 14+15).

7. Viewfinder

With the telescope roughly aligned, loosen the tube ring screws (No. 1, 8) to rotate the tube for a comfortable viewing position for both the eyepiece and viewfinder.

Fine alignment uses the viewfinder. Center Polaris (No. 16) in the viewfinder's crosshairs (No. 17). Use the flexible shafts (No. 15, D and E) for precise adjustments.

8. Observation

Once Polaris is centered in the viewfinder, it should be visible in the eyepiece. Use the flexible shafts for finer alignment and the focus wheel (No. 15, F) for sharpness. Changing eyepieces allows for higher magnification. Note that star magnification changes are subtle.

? Tip: Eyepieces magnify the image. Lower focal length eyepieces provide higher magnification. Start with a low magnification eyepiece (e.g., 20mm) and increase as needed.

9. Finding a Star

Initial star navigation can be challenging due to celestial movement. Polaris is a fixed point. Observe well-known constellations visible year-round. Remember that star positions change with seasons, dates, and times.

If you align the telescope on a star, it may disappear after a few minutes. Use the flexible shaft (No. 15, D) to follow the star's apparent path.

10. Accessories

The telescope includes three eyepieces (No. 2, 18). Magnification is calculated by dividing the telescope's focal length by the eyepiece's focal length.

Magnification Formula: Focal Length (Telescope) / Focal Length (Eyepiece) = Magnification

Examples:

• 900mm Telescope / 20mm Eyepiece = 45x (67x with 1.5x erecting lens)
• 900mm Telescope / 12mm Eyepiece = 75x (112x with 1.5x erecting lens)
• 900mm Telescope / 4mm Eyepiece = 225x (337x with 1.5x erecting lens)

The diagonal mirror (No. 2, 19) provides a horizontally reversed image, suitable for terrestrial viewing. For an upright and correctly oriented image, use the erecting lens (No. 2, 20). Remove the diagonal mirror, insert the erecting lens, then the eyepiece.

11. Dismantling

After use, store the telescope in a dry, well-ventilated area. Separate components if possible. Replace dust protection caps. Store all eyepieces and accessories in their original containers.

? Tip: The erecting lens is not recommended for astronomical observations; use the diagonal mirror instead. It is suitable for terrestrial viewing.

Notes on Cleaning

Clean lenses (eyepieces and objectives) only with a soft, lint-free microfiber cloth, using gentle pressure to avoid scratches. For stubborn dirt, use a lens cleaning fluid on the cloth. Protect the device from dust and moisture; allow it to acclimatize to room temperature after use, especially in high humidity, before storing.

Part III - Appendix

1. Possible Observation Targets

Here are some interesting celestial objects to observe:

The Moon (No. 20)

Earth's natural satellite. Diameter: 3,476 km. Distance: 384,400 km. The Moon's phases change as it orbits Earth.

Orion Nebula (M42) (No. 21)

Located in the Orion constellation, approximately 1,344 light-years away. It is the brightest diffuse nebula, visible to the naked eye, and a significant object for telescopes.

Ring Nebula (M57) (No. 22)

In the Lyra constellation, about 2,412 light-years away. Often considered a prototype planetary nebula, it is a prominent feature of the summer sky. It appears as a ring of bright material surrounding a central star.

Dumbbell Nebula (M27) (No. 23)

In the Vulpecula constellation, approximately 1,360 light-years away. It was the first planetary nebula discovered. It appears as a dumbbell shape, similar to the Ring Nebula when viewed from a different angle.

2. Troubleshooting

Problem: No image

Solution: Remove dust protection cap from the objective opening.

Problem: Blurred picture

Solution: Adjust focus using the focus wheel.

Problem: No focus possible

Solution: Wait for temperature to balance out.

Problem: Bad picture quality

Solution: Never observe through a glass surface.

Problem: Object visible in viewfinder, but not in telescope

Solution: Adjust viewfinder scope (See Part I, Section 6).

Problem: Crooked image despite diagonal mirror

Solution: Ensure the diagonal mirror is vertical in the eyepiece connection.

Disposal

Dispose of packaging materials properly according to local regulations. Contact your local waste-disposal service or environmental authority for guidance.

Warranty & Service

The standard warranty is 2 years from the purchase date. For extended warranty benefits, register on the manufacturer's website (www.bresser.de/warranty_terms).