Rangefinder Binoculars – How Do They Work?

 

 

What are Rangefinder Binoculars and How Do They Work?

If you know the height of an object, such as a hill or navigation marker (often printed on navigation charts), and can measure the angle to its top using binoculars equipped with a rangefinder reticle, you can calculate your distance from that object.

Many of the best marine binoculars come with a reticle rangefinder, that enable those aboard boats, yachts and other marine vessels to calculate the distances

What is a Rangefinder Reticle?

A reticle (or reticule) is a net of fine lines or fibers in the eyepiece of the binocular, monocular, microscope, scope or other optical device used for sighting and taking other measurements.

Rangefinder reticles are obviously used to calculate the distance between you and an object you are observing, but can also be used to calculate the height of an object or the included angle of a viewed object.

 

How do Rangefinder Reticles work?

There are several systems used to calculate the distance by rangefinder reticle binoculars and scopes. The simplest and most commonly used system involves comparing a scale or measuring marks on the reticle in the binocula field-of-view against a known sized object that you are looking at. The military and hunters refer to this as the Mil-Dot reticle and the formula is known as the Mil-dot formula:

 

Mil-dot Formula

Take the height or length of the object, then calculate the distance away from that object using simple math. You can also calculate the height or length of the object if you know the distance that you are away from it.

 

If you are on your boat and look through your reticle rangefinder binoculars at a house that you knew to be 30 feet tall, and the scale height on the reticle rangefinder reads 40:

Distance = (Height of House / Scale Height) / x1000

= (30′ / 40) x 1000

Distance to the house = 750 feet

Do Rangefinder Reticles Work?

Yes, but in terms of providing an exact distances, they aren’t as accurate or fast as a laser rangefinders, but they can give you a good idea and work over long distances.

How accurate they are depends on the user lining up the target and of course how accurate you are when estimating the height or length of the target. If you know the exact height of the target and line it up very carefully on the reticle, they will be very accurate.

For boating binoculars and other marine uses, reticle rangefinders are in most cases the best solution.

See: Best Rated Rangefinder Binoculars.

 

Related Articles from The Lake Life:

• Rangefinder Binoculars – How Do They Work?
• Top Rated Marine Binoculars
• About Binoculars
• Bird Watching Binoculars Buying Guide
• Marine Binoculars Buying Guide

 

Top Rated Marine Binoculars

 

 

 

Choosing a pair of binoculars for use on a boat can be tough; some choices are better than others. The marine environment combines constant dampness with temperature changes, that can cause the  interior lenses of non–waterproof binoculars to fog. Waterproof construction, with the interior o-ring sealed and filled (charged) with dry nitrogen, combined with flotation in the strap, can protect your binoculars if they fall overboard.

Here are the four top-rated marine binoculars – rated by the people who bought them.

 

Carson 3D Series High Definition Waterproof Binoculars with ED Glass

Waterproof and fogproof – these are the perfect binoculars for hunting, bird watching, camping, hiking, backpacking, traveling, concerts, sporting events and other outdoor adventures.

FEATURES:

• ED Glass for Sharper and Brighter Images
• Rubberized armor Coating
• BinoArmor Deluxe carry case, Neck strap, Shoulder harness, Lens covers and Lens cloth
• Field of View: 314 feet at 1,000 yards; Eye Relief: 16mm | BAK-4 Prisms | Weight: 1.4 lbs.
• Backed by America’s best binocular warranty

 

Steiner 8×30 Military/Marine Binocular

These tough, rugged binoculars are rainproof and fog-resistant, and feature a wide field of view. Their unique auto-focusing feature enables focusing at the increased distances over water.

FEATURES:

• Rugged binocular with 8x magnification and 30mm objective lens
• Unique auto-focusing design focuses from 20 yards to infinity
• Tough rubber-armored housing; long 20mm eye relief
• Rainproof, fog-resistant construction; wide field of view
• Measures 6.8 x 2.4 x 4.6 inches (W x H x D); weighs 18 ounces

 

Vanguard Endeavor ED 8420 Binocular, 8×42

These lightweight binoculars are totally waterproof and fogproof and feature ED glass for high resolution.

FEATURES:

• ED glass reduces color dispersion to provide high resolution colors and clarity
• Bak4 phase-coated prisms and fully multi-coated lenses
• Three stage twist out eyecups with long eye relief and locking diopter ring
• 100% waterproof and fogproof
• Advanced lens coatings for enhanced light transmission even in low light conditions
• Lightweight, open bridge body design with large, precise focus wheel
• Premium Lifetime Warranty
• Magnification: 8x, Objective Lens Diameter: 42mm, Field of view: 367 ft/1000 yards, View angle: 7.0 degrees, Near focus: 6.6 feet, Eye relief: 19 mm, Weight: 25.8 ounces

 

Bushnell H2O Waterproof/Fogproof Roof Prism Binocular

Beautifully designed, durable, waterproof and fogproof binoculars made with quality materials and tested extensively to provide quality optics with stunning clarity.

FEATURES:

• 100% waterproof, O-ring sealed and nitrogen purged for reliable, fog-free performance
• BaK-4 prisms and multi-coated optics offer crisp clear images with improved light transmission
• Non-slip rubber armor and Soft Texture Grip absorbs shock and provides a firm grip
• 10x magnification and 42mm objective diameter; 12-foot close focus distance; 17mm eye relief
• Large center-focus knob for easy adjustments with Twist-up eyecups
• Limited lifetime warranty

Related Articles from The Lake Life:

• Rangefinder Binoculars – How Do They Work?
• Top Rated Marine Binoculars
• About Binoculars
• Bird Watching Binoculars Buying Guide
• Marine Binoculars Buying Guide

About Binoculars

How Binoculars Work

In their most basic construction, binoculars consist of two lenses. The lens nearest whatever is being observed (objective lens) provides an image, which can then be enlarged by the lens closest to the viewer’s eye (eyepiece lens), by moving it closer to or further away from the objective lens.

Because the light when directed through the lenses has been refracted or bent,  the time the viewer sees the image it is upside-down, and back to front . Two prisms are placed inside the binoculars, between the objective and the eyepiece to fix this.

Power, Light and Weight

The optic power is expressed as two numbers, such as 7 x 35. The first is the number of times magnification, and the second is the diameter of the objective lens. A larger objective lens will capture more of the available light and so is more useful in low-light situations. Continue reading →

Binoculars are for the birds

Identifying and observing birds requires, above all, patience, passion, and the ability to maintain a large mental catalog. Beyond that, it requires binoculars. Birding binoculars feature a full nest of features and specs, but they all pale in importance to light-gathering capacity. Magnification is important, yes, but light gathering, light transmittance, and close focus ability should be your primary equipment concerns. Some birders may be willing to sacrifice close focus, as it tends to increase the price substantially, but we find that capturing every fine detail enhances the overall bird watching experience.

 

Best Rated Birding Binoculars

 

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Water You Looking At?

Ahoy! Before taking your maiden voyage with a pair of marine binoculars, it’s important to be sure you’re getting the right pair. Combining optics and the open water creates a unique set of challenges – namely, the movement of the water makes a steady image difficult to maintain, and potential water damage is a major concern. And since distance is much more difficult to gauge on water, you’ll want to check out the unique range-finding features often found in marine binoculars.

As always, it’s important to give well-known binocular brands top-tier consideration. Marine binoculars from Bushnell,Steiner, and Canon are always a safe bet, though any listed on our marine binoculars page are well-suited for the water. Read on for details about what makes them special.

The Marine Scene

If your main, or only, pair of binoculars is going to be used on water, we suggest getting specially designed marine binoculars. This is especially true if your chosen body of water is large or has the potential for big waves. For example, many standard land binoculars advertise water resistance, but quality marine binoculars are nitrogen-purged and o-ring sealed, making them totally waterproof to prevent fogging and any water infiltration.

Marine binoculars are predominantly in the 7×50 range to allow an ample amount of light transmission through the exit pupil, a good field of view, and adequate magnification. Since the function is less geared toward sightseeing and more toward finding landmarks on the shore and horizon, a wider field of view is essential. Some choose binoculars with smaller objective lenses, but these will be much less useful if you find yourself on the water on a cloudy day when you need them the most. Many of our highest-rated marine binoculars fit all of these characteristics, and are right at home on your boat or dock.

Image-Stabilized Binoculars, Reticles, and More

Image-stabilized binoculars are indispensable on the water. As the rolling tide moves you up and down, the mechanics of these marine binoculars keep your image steady and your head from getting seasick. Of course, standard binoculars can still be suitable for marine use, but after choosing magnification and objective lens size, image stabilization is what will really make the difference. Note – a set of marine binoculars with an extra-wide enough field of view won’t necessarily need image stabilization.

Some marine binoculars go the extra nautical mile and provide a built-in rangefinder, compass, and/or reticle. These features can help you find magnetic north, and properly judge object size and distance. Using these features properly may take a bit of practice, but once you do, you can decrease the number of gadgets packed before each marine journey. Check out our wide selection of rangefinder marine binoculars and judge your distance to optical perfection.

>>Visit The Binoculars Shop Here<<

 

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Whether you’re in the stands at a football game, bird watching, or stargazing, a good pair of binoculars always comes in handy. They are simply two small telescopes, one for each eye, mounted on a single frame, which magnify a single image in order for better viewing. Unlike a monocular (or telescope), binoculars allow a user to see with depth and perception by using both eyes simultaneously.

Field Glasses or Binoculars

There are two different types of binocs; field glasses and prismatic binoculars. Although the term field glass is often used interchangeably with binocular, there are differences.Field glasses are a type of binocular that uses both the objective lens, the large lens through which light first enters, and a second lens inside each tube, which inverts and reverses the image in order for the user to see a right-side-up picture.Field glasses can magnify an image up to five times. For greater magnification purposes, the simple field glasses would become too long and heavy, and users would instead want to consider the more-popular prismatic binoculars.

Continue reading →

Everything you’ve ever needed to know about binoculars- in one handy place.

Following is a list of binocular terms, listed alphabetically:

Aperture – The size of the binoculars’ objective lenses. The second number represented in the numbers describing a set of binoculars, measured in millimeters. Example: In the Steiner 8×22 Predator Binoculars, 22 would represent the aperture.

Aspherical Lens – A lens with flattened edges, useful for a clearer, sharper image.

BaK-4 Glass – Premium, high-density barium crown glass that minimizes light scattering inside the binocular tubes and allows bright, crisp, clear viewing.

Center-Focus – A mechanism that allows both eyepieces to be adjusted at the same time, useful for rapid focus.

Central Focusing Wheel – A wheel mounted in the middle of the binoculars, allowing for focusing.

Coated/Multi-Coated Glass – Thin layer(s) of coating added to the binocular glass to help reduce reflections. Examples: (C) Coated optics – one or more glass surface is coated. (FC) Fully coated optics – all glass surfaces that have any vulnerability to air are coated. (MC) Multi-layer coated – one or more glass surfaces is coated multiple times. (FMC) Fully Multi-Coated – all glass surfaces susceptible to air are multi-coated. Continue reading →