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Binoculars a Boating Essential

Binoculars an Essential piece of Marine Safety Equipment

Binoculars can be a very important and versatile part of your vessels safety equipment! As a life long sailor who grew up on the Gulf of Mexico I can attest that having a good pair of binoculars is not only important for spotting other vessels, buoys, and channel markers, but very handy in locating fish when off shore. Your probably thinking ok but I have a fish finder and GPS for that, well a good pair of binoculars can help you find the right spot to fish when you use them to locate birds who often times will follow schools of bait and pelagic fish. So its very important to keep a quality pair of binoculars around at all times.

Choosing the Right Binoculars

You may have already asked yourself do I really need a pair of  marine binoculars? Well if you plan on spending any amount of time on the water you should defiantly own a pair of Binoculars and have the right pair to assist you effectively in navigating or in identifying hazards to navigation. Through the course of this article we are going to explore all of the functions of modern Binoculars and break down the differences in the various types and magnification levels.

Binoculars How They Work

Binoculars are derived from traditional telescopes, which consist, of two lenses. The lens nearest what is under scrutiny is the objective lens. It provides an image, which can then be enlarged by the lens nearest the viewers eye the eye piece. A pair of  boat binocularscan be seen as two telescopes, side by side, That together produce an image which has the depth of field that we are used to, instead of just a large flat image. The light is refracted (bent) as it is directed through the lenses, by the time the viewer sees the image it is back to front, and upside-down. Two prisms are placed inside the binoculars, between the objective and the eyepiece to correct this. To have a complete understanding of your binoculars begins with knowing how each of the parts works together to bring an image to your eyes. Once you know how these parts work, you'll be able to focus in on things in an instant.

Binocular Lenses

Binoculars contain a series of lenses. Anywhere from two to four lenses can found in a pair of field binoculars. A general rule of thumb is that the more lenses a binocular has, the greater magnification power it offers. Therefore, high-powered binoculars would have a larger number of lenses. The lenses are actually curved pieces of glass. They are spaced apart inside the binocular. As the image travels from one lens to another, it is magnified. The glass at the end of the binoculars is the objective lens; the lens by the eye is the eyepiece. Binoculars rate how many times closer to you the subject appears through the lenses. Therefore, a binocular with a rating of 7x would bring the image 7 times closer to you and a binocular with a rating of 10x would bring the image 10 times closer to you.

Prisms in Binoculars

A prism is located between the lenses and the eyepieces. The prism has two jobs. First, the prism bends the light that enters the binoculars and helps magnify the image. Second, it flips the image. That is because the image is actually upside down as it passes from lens to lens. Without a prism, you would view an upside-down image.


The eyepiece is the last part of the magnification process. The eyepiece brings the image into complete focus and sends it to the eye.

Center Focus Wheel

Most binoculars come with a center focus wheel, which allows you to customize your view. The center focus wheel is a movable dial located between the eyepieces. Adjusting it changes the distance between the eyepieces and the lenses, enabling you to see a sharp image at several different distances. The center focus wheel brings the image into focus for your left eye.

Right Eye Diopter

The right eye diopter dial is usually located near the right eyepiece. The diopter helps adjust for any difference in strength between your left and right eyes. To focus an image with binoculars , first look through the binoculars with your left eye open and your right eye closed. Bring the image into focus using the center focus wheel. Now close your left eye and open your right eye. With just your right eye looking through the eyepiece, make adjustments with the diopter to bring the image into clear focus for your right eye. You may then open both eyes and use the center focus wheel for any fine-tuning.