Binoculars fall into two categories of shipboard gear, safety and navigation. With one-handed operation, binoculars leave the other hand free for vessel operation. When distant channel markers need to be identified for navigational purposes, binoculars provide an early "visual" on the target, easing anxiety.
PROPERTIES
There are different properties to binoculars that assist in the selection to suit each sailor’s needs.
Magnification, or power, is represented by the first of two digits separated by an "x." For example, on a 7 x 50, the seven indicates that magnification is 7 times, or in other words, the object you’re observing appears seven times closer than looking at it without binoculars. Greater magnification is not always better. A larger magnification allows less light to pass through, resulting in a narrower vision of the object (field of view), distorted depth of view, and wavering, or shaking, becomes apparent.
| |  Binoculars/6918_binoculars.jpg" width=123>
|
| |
Relative Brightness is the performance level of
binoculars in dim light. The second digit, the"50" of the 7 x 50, represents the diameter of the front lens, the objective lens, in millimeters. The larger the diameter of the objective lens the more light is let in for more brightness. Within each barrel there are several glass surfaces which, as the light comes through, hits these surfaces and loses a small amount of light making it to the eye through the rear, also known as the "ocular" lens. More relative brightness permits more detail and color to be observed.
Field of View is the width of the area viewed through the binoculars. The manufacturer can state this as, for instance, 400 feet at 1000 yards. In other words, viewing an object at 1000 yards you can also see at a width of 400 feet. If the object, centered, were 50 feet wide, your vision on either side of that object (if centered) would be 175 feet.
Depth of Field is the near to far distance that remains in focus. A low depth of field, which is related to magnification, means you’ll be continuously refocusing
Focusing permits the viewer to see the image clearly. There are two methods of focusing; one is called center eye focus and the other is individual eye focus.
- Center eye focus uses a thumb wheel located between the barrels. Some center eye focus models are available with one adjusting eyepiece to compensate for the vision differences between your two eyes. There are also models with features, fast-focus, auto-focus and perma-focus, that permit binoculars to remain in focus from a particular distance to infinity, for different viewers.
- Individual eye focus permits the viewer to rotate the objective lens end for focusing to each individual eye. For people whose eyes have different prescriptions, this is the preferred method for focusing to get clear images.
FEATURES
| | Binoculars/7695_binoculars.jpg" width=138>
|
| |
Dry nitrogen instead of air within the housing minimizes interior corrosion and fogging. - Objective lens coatings increase relative brightness by increasing the amount of light that makes it to the eye, minimizing the light loss over the glass surfaces.
- Image stabilization makes necessary corrections from vibration or motion. Quick scanning both horizontally and vertically becomes smooth and without lags in viewing.
- Built in compass and range finders are offered by some manufacturers. Illuminated compasses for night viewing are the most useful.
- With night vision, objects are clearly distinguishable for up to several hundred yards using existing light that is amplified. In complete darkness night vision is heightened with the use of infrared.
TIPS
| | Binoculars/8761_binoculars.jpg" width=150>
|
| |
Look for binoculars that are fully coated or are fully multiple coated. The multiple coating further reduces light loss over the glass surfaces. - Center eye focus binoculars cannot be made waterproof unless they have roof prisms. With roof prisms, the lenses can be placed in line resulting in a more compact form.
- Waterproof binoculars are tested at a set depth for a set time in order to be labeled waterproof. Check the manufacturer’s test specifications against water resistant binoculars.
- Check the manufacturer’s specifications to see if dry nitrogen has replaced air within the housing.
- Rubber housed binoculars are easier to grip, won’t slide if dropped and are protected from everyday abuse.
- Buy lens covers to protect the lenses if they’re not included with the binoculars.
- Buy a comfortable neck strap if not included with the binoculars. This will minimize, if used, the chance of dropping the binoculars.
- If you wear glasses, buy binoculars with eyecups that retract or roll down.
View products
Linear Mode
