Additional Binocular Considerations
Focusing
The precision and ease of focusing are vital when selecting binoculars or scopes. Most optics feature a focus knob that you turn with one finger while viewing. Ideally, this knob should allow one full revolution to transition from one focal extent to the other.
Achieving optimal focus may require fine adjustments. Manufacturers address this in several ways:
- Multiple Revolutions: Increasing the number of revolutions for the focus knob allows finer adjustments but can slow down the focusing process and cause confusion.
- Variable-Speed Focus Dial: Rapid turning provides coarse adjustment, while slow turning allows fine adjustment. This system is effective but may require practice to master in the field.
- Dual Focusing Knobs: Commonly found on scopes, this setup includes separate knobs for coarse and fine focusing.
Additionally, the focus knob should be comfortably positioned under your index finger and operate smoothly without any looseness, stiffness, or irregular movement.
Diopter Adjustment
All binoculars feature a diopter adjustment to fine-tune the focus for each eye, compensating for differences in vision between your eyes. Typically located on the right eyepiece, some models incorporate it into the center focusing wheel. The adjustment should be firm to maintain its setting without frequent readjustment.
To adjust:
- Focus on an object 50-75 feet away with your right eye closed.
- Use the focus wheel to bring the object into sharp focus for your left eye.
- Close your left eye, open your right eye, and use the diopter adjustment to bring the object into sharp focus without adjusting the focus wheel.
- Both eyes should now be in sharp focus simultaneously.
Close Focus
Close focus refers to the nearest distance at which binoculars or scopes can sharply focus an image. A close focus of 6 to 8 feet is advantageous for observing birds, butterflies, and other small subjects. Higher magnification typically increases the minimum close focus distance, but many mid and high-end binoculars can now achieve close focus at 5-8 feet even at 10x magnification.
Field of View (FOV)
Field of View (FOV) is the width of the visible area through the optics, usually measured in feet at 1000 yards. Higher magnification narrows the FOV, making it harder to locate and track moving birds. A wider FOV makes it easier to find and follow birds, particularly for beginners or in dense environments.
Depth of Field
Depth of field is the range of distance within which objects remain in sharp focus. Higher magnification reduces depth of field, requiring more frequent focus adjustments for closer objects. A greater depth of field allows multiple objects at varying distances to remain in focus simultaneously.
Weatherproofing
Weatherproofing is essential for outdoor use. While "weather-resistant" optics can handle light showers, true "weatherproof" or "waterproof" optics are sealed to prevent moisture and dust from entering, ensuring durability in wet conditions. Optics with internal focusing mechanisms are generally more reliable for weatherproofing.
Nitrogen or Dry Gas Fill
Filling optics with nitrogen or another dry gas prevents internal fogging caused by temperature changes. This feature is crucial for birding in cold weather to avoid condensation and potential mold growth inside the optics.
Rubber Armoring
Rubber armoring protects binoculars and scopes from corrosion, dirt, and impact damage while providing a comfortable grip. Modern rubber armoring is typically made from urethane, which is resistant to bug repellents. However, it adds to the weight of the optics.
Conclusions
- Focusing: Speed and precision are critical. Options include multiple revolutions, variable-speed dials, and dual knobs.
- Close Focus: Ideally under 10 feet for versatility.
- Field of View: Wider FOV is better for tracking and locating birds.
- Depth of Field: Greater depth of field reduces the need for frequent focus adjustments.
- Weatherproofing: Essential for durability and better warranty coverage.
- Nitrogen Fill: Prevents internal fogging, crucial for cold weather use.
- Rubber Armoring: Adds protection and comfort, with a slight increase in weight.
By considering these additional factors, you can ensure your optics meet your specific needs and provide an enhanced birding experience.
