Binoculars, Magnifying Spectacles, Sport Glasses

What are Binoculars?

Binoculars are a type of telescope that enables the user to see far away objects using both eyes at the same time. This requires using two separate telescopes, one for each eye, which allow for binocular vision. Binoculars have three-dimensional viewing and promote visual clarity, unlike monoculars that use only one telescope device to see objects. They are normally small enough to be handheld, and many types are lightweight so they can be stored and carried easily.

For both hobbyists and professionals, binoculars have unlimited practical uses. They are handy to have at professional sporting events in which a spectator may be far away from the action. They are also a must for bird watchers and hunters. In a professional setting, binoculars are essential for seafaring vessels. They can be useful for a variety of scientists, such as meteorologists, geologists, and other environmental professions. Military applications often use different types of binoculars, as well.

Binoculars incorporate a series of prisms to magnify an image. To take in all the light it can capture, a large ocular lens is on the far end. But, the image is inverted and the human eye would see an upside-down image, which is not very helpful. That is why a prism is placed between the eye and the first lens to flip the image over. The image must then be focused. This can be done by moving the individual eyepieces to line up each eye, or by using the center focus adjustment knob.

The most commonly used types of binoculars are porro prism binoculars. These utilize a positive eye piece, or ocular, to see images. This system inverts the image, and a system of prisms, or mirrors, are used to make the image appear upright. The porro prism system allows for greater image quality and magnification.

What are the Different Types of Prisms?

The most important characteristic that distinguishes one model of binoculars from another is their optical design. They are available in three distinct optical designs, which are roof prism, porro prism, and reverse porro prism. The roof prism design relies on even spacing and linear characteristics. The narrow barrels, the eyepieces, and the lenses are all mounted in a straight line and equal distances apart. Focus is internal instead of external, allowing the user to shift the lens inside its casing to sharpen the focus. A huge advantage of this streamlined design is that roof prism binoculars are often waterproof. This allows them to be used in many types of environments or weather.

Porro prism binoculars tend to be larger and heavier that roof prism types. This design arranges the eyepieces closer together than the objective lenses, and are not evenly spaced. Focus controls allow for external focus only because they are on the outside of the binocular casing. This design is the most traditional and most common design for binoculars. This type also allows for a high amount of light gathering and depth perception.

Reverse porro prism binoculars are opposite of the porro prism design in which the objective lenses are closer together than the eyepieces. Reverse porro prism are among the smallest of binoculars and they do not perform well when magnification, great distance, and depth are required. They use external focus controls and are usually not waterproof.

How do I Choose the Best Binoculars?

When deciding to purchase binoculars, consider what they will be used for. If planning to use them outdoors for sporting events, binoculars that are waterproof may be needed. Waterproof binoculars are an option when using them while around water, or when boating. If a small, lightweight pair of binoculars are desired for portability, consider buying compact binoculars. For low lighting or outdoor evening use, night vision binoculars may be a good choice.

For many various requirements of usage, the best choice may be an all-purpose pair of binoculars. This versatile type can be compact and affordable, but, they may not offer a powerful zoom. If planning on using them to study close-up details of distant wildlife or objects, higher magnification may be necessary. However, if you require a powerful zoom magnification, image quality may be compromised. A high-powered zoom may not make image stabilization possible. Brightness and contrast may also be less than satisfactory with this type.

If your binocular utilization will mainly be for watching sporting activities, such as a baseball game at the ballpark, consider designs that offer an adequate field of view. If the field of view is not good, the ability to zoom in through high magnification may still be possible, yet more of the action may not be seen. Field of view is more important for watching sporting events than for bird watching, where basic, close-up detail is necessary. Wide angle binoculars may work well if you plan on using them for the theater and concerts.

When using binoculars in low lighting conditions or on very cloudy days, consider features such as relative brightness. If you require binoculars for nighttime viewing, choose a pair that is especially made for that purpose. Night vision binoculars will normally cost more since they use more advanced technology, such as infrared lighting. For hiking and camping, buying binoculars that are rugged and durable will be helpful. Choose designs that have a rubberized coating as well as being waterproof. This material will absorb shock if they are dropped onto the ground, and will improve the grip on them. If binoculars are needed for hunting, a more slim and compact design that can easily fit into a pocket may be preferred.

Rehabmart is pleased to offer a wide variety of binoculars from top quality vendors, which include MaxiAids and LSS.

Hulet Smith, OT
Rehabmart Co-Founder & CEO

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