National Geographic Expedition Series 42mm Single Bridge Roof Binoculars

Eyecup Adjustment

Diagrams illustrate two types of eyecup adjustment: 'Twisted Eyecup' showing the eyecup being rolled down, and 'Rolled Eyecup' showing the eyecup being twisted down. The text explains how to adjust eyecups for users with or without eyeglasses to achieve a full field of view. If you are not wearing eyeglasses or sunglasses, keep the eyecups fully extended ("up" position). If you are wearing glasses, roll down or twist the eyecups to the down position. This brings your eyes closer to the binocular's eyepiece lens to ensure you can see the entire image (full field of view with no "cutoff" or "tunnel vision"). Diagram may vary.

IPD (Interpupillary Distance) Adjustment

The distance or spacing between the center of the pupils, called "interpupillary distance" (IPD), varies from person to person. To adjust the binocular to match your eyes, follow these simple steps:

1. Hold your binocular in the normal viewing position. Grasp each barrel firmly.
2. Move the barrels closer together or further apart until you see a single circular field (don't worry about focus yet).
3. Always re-set your binocular to this position before using it.

A visual representation shows two binoculars being moved closer or further apart to match the interpupillary distance (IPD) between a person's eyes, resulting in a single circular field of view.

Diopter Adjustment and Focusing

Follow these steps for precise focusing:

1. Adjust eyecups and interpupillary distance as described in the previous sections.
2. Set the diopter adjustment ring to zero and view a distant object.
3. Keep both eyes open at all times.
4. Using a lens cover or your hand, cover the objective (front) lens of the same side of the binocular that has the diopter adjustment ring (usually the right side).
5. Using the center focus wheel, focus on a distant object with fine detail (e.g., brick wall, tree branches, etc.) until it appears as sharp as possible.
6. Uncover the objective lens on the diopter side, cover the other objective lens (the left side), then view the same object.
7. Using the diopter adjustment ring, move the diopter adjustment marker to the "+" or "-" until you reach focus.

A diagram shows the diopter adjustment ring and marker on the binocular, indicating adjustment points '+' and '-' for focusing.

Caution: Over-turning or forcing the diopter ring can cause damage or cause the eyepiece to break away from the chassis.

Your binocular should now be adjusted for your eyesight. Focusing for any distance can now be done simply by turning the center focus wheel. Make a note of your diopter setting for future reference.

Neckstrap Attachment

To securely attach your binocular to the binocular strap:

1. Thread the end of the strap from the bottom up through the strap attachment loop.
2. Hold the buckle and thread the end of the strap inside the buckle.
3. Adjust the overall length and pull the strap webbing tight so it is secure within the buckle.

Illustrations show how to thread the neckstrap through the strap attachment loop and secure it with the buckle.

Waterproof / Fogproof Models

National Geographic binoculars are designed and built utilizing the latest waterproof and fogproof technology. Waterproof models are O-ring sealed for complete moisture protection. Fogproof protection is achieved from dry nitrogen purging that removes all internal moisture. (This will be noted on the product packaging).

Water-Resistant Models

Binoculars that are water-resistant have a housing that protects the binocular from minor exposure to damp conditions such as mist or splashes and are not protected from full submergence in water. (This will be noted on the product packaging).

General Care

• Do not expose non-waterproof models to heavy rain or other excessive moisture.
• If your binocular has roll-down, flexible eyecups, store it with the eyecups up. This avoids excessive stress and wear on the eyecups in the down position.
• Avoid sharp impacts. Use the included neckstrap to avoid accidentally dropping the binoculars to prevent mis-alignment of the optics.
• When not using them, store your binoculars in the provided case in a cool, dry place.
• Avoid storing the binoculars in hot places, such as the passenger compartment of a vehicle on a hot day. The high temperature could adversely affect the lubricants and sealants.
• Never leave the binocular where direct sunlight can enter either the objective or the eyepiece lens. Damage may result from the concentration (burning glass effect) of the sun's rays.
• All moving parts of the binocular are permanently lubricated. Do not try to lubricate them.

Lens Cleaning

1. Blow away any dust or debris on the lens (or use a soft lens brush).
2. To remove fingerprints or other smears, clean with a soft cotton cloth rubbing in a circular motion. A "microfiber" cleaning cloth (available from camera or computer retailers) is ideal for the routine cleaning of your optics.
3. For a more thorough cleaning, photographic lens tissue and photographic-type lens cleaning fluid or isopropyl alcohol may be used. Always apply the fluid to the cleaning cloth – never directly on the lens.

Tripod Mounting

(Tripod and tripod adapter not included) To attach the binocular to a tripod or mono-pod, unscrew (counter-clockwise) the cap which covers the threaded socket at the far end of the center hinge, and set it aside in a safe place. Use a compatible binocular tripod adapter accessory to attach your binocular to any standard tripod in a horizontal position to provide a stable image during prolonged viewing.

Disposal Information

Dispose of packaging materials as legally required. Consult the local authority on the matter if necessary and recycle materials when possible.