Choosing the Right Binocular – We are dealers for Zeiss, Vortex, and Celestron


Before we go into this binocular training course, please read the Vortex binocular warranty.

VIP Warranty From the Folks at Vortex

Our warranty is about you, not us. It’s about taking care of you after the sale. The VIP stands for Very Important Promise to you (our customers) that we will do the following:

Repair or replace your Vortex product for any reason at NO CHARGE TO YOU. It doesn’t matter how it happened, whose fault it was, or where you purchased it.

  • Unlimited lifetime Warranty
  • Fully transferable
  • No warranty card to fill out
  • No receipt needed to hang on to

If you ever have a problem, no matter the cause, we promise to take care of you.

This, my friends, is an outstanding warranty that adds value to your binocular purchase.


Binocular Basics

Binoculars are available with various prism designs, focus systems, glass quality and lens coatings, with protection from water damage and internal fogging. Most binoculars are multi-purpose instruments, suitable for a number of different activities including hunting, birdwatching, sporting events, hiking, fishing, and more.

Optical Design

Binoculars use glass prisms to orient the image so that it is right side up and not backwards—which is how the image would appear without the prisms. There are two basic prism designs used in optical systems today: the roof prism design with straight barrels and the more traditional looking Porro prism design with offset barrels.

Roof Prism Design

Roof prisms are generally smaller, more streamlined in size, and better able to tolerate rough conditions than many Porro prism binoculars of comparable configurations.

Most roof prism models have an internal focusing mechanism that gives them a high degree of structural integrity—making them less susceptible to internal fogging and entry of dust and moisture. However, the complex prism configuration and precise tolerances required during the manufacturing process often make roof prism binoculars more expensive than Porro prism binoculars. The careful assembly of more expensive roof prisms enhances overall optical performance, and contrasts greatly with inexpensive models which generally are inferior in optical quality.

Porro Prism Design

This classic-looking binocular uses the Porro prism design—a less complex prism design than the roof prism.

One of the benefits of the Porro prism is that it costs less to manufacture a binocular with excellent image quality using this design. However, the Porro prism binocular is generally larger and heavier than a roof prism binocular of the same magnification and aperture. The Porro prism design is also more difficult to waterproof and keep aligned. Compared to roof prisms, Porro prisms may be more likely to shift around inside the binocular housing with rough handling.

Reverse Porro Prism Design

A variation on the Porro prism design is the reverse Porro prism. This compact design reduces the overall size of a binocular while maintaining image quality at a lower price.

Magnification and Aperture

The magnification and aperture are designated with two numbers. You’ll usually find the designation for a binocular on the focus wheel plate. The 8×42 and 10×42 binoculars are two very popular designations—read as “eight by forty-two” and “ten by forty-two”.

The First Number: Magnification (7x, 8x, 10x…)

The first number indicates the magnification or power of a binocular. This tells us how much larger the object will appear compared to what you would see with the unaided eye. If you look through an 8x binocular, read as “eight power”, an object will appear eight times closer or larger.

Keep in mind when considering magnification that more is not necessarily better

• As magnification increases, brightness and clarity generally decrease.
• As magnification increases, field of view generally becomes narrower.
• As magnification increases, depth of field becomes shallower.
• As magnification increases, adverse atmospheric conditions, like heat waves, are more noticeable.
• As magnification increases, fine hand and finger tremors are more noticeable.

The Second Number: Aperture (26mm, 32mm, 42mm, 50mm…)

The second number of a binocular designation refers to the aperture of the objective lenses and determines how much light enters the optical system. All else being equal (glass quality and anti-reflective coatings), a larger objective lens will gather more light and provide greater image detail, clarity and brightness.

The size of the aperture is the greatest indicator of the physical size and weight of a binocular. Magnification, however, has little effect on the size of most binoculars. For example, an 8×42 binocular is larger than an 8×28, but an 8×42 may be very similar in size to a 10×42 in the same series. Keep in mind this general rule when comparing binoculars of the same design (e.g., all are roof prisms): the larger the objective lens, the larger the binocular.

• Compacts or Pockets: 20 mm–28 mm, generally weigh less than 12 ounces.
• Mid Sized: 30 mm–36 mm, generally weigh between 16 and 20 ounces.
• Full Sized: Over 36 mm, generally weigh over 20 ounces.

Understanding Key Specifications

Eye Relief

Very important for eyeglass wearers

Eye relief refers to the distance behind the binocular eyepiece at which the whole field of view is clearly visible to the observer. If the eye relief is long enough, a user should see one circle in the viewing area. If the user appears to be “looking down a tunnel”, then the eye relief is probably not long enough. Vortex binoculars have eye relief that is long enough for use with eyeglasses (ranging from 15 mm to 21 mm). Adjustable eyecups can be twisted or folded back for more comfortable viewing.

Close Focus

Can be significant for bird watchers

The close focus distance of a binocular depends on its optical design and, to a lesser degree, on the person’s eye vision. A close focus measurement of eight to ten feet is acceptable to many people, but others may need to focus even closer than this. Most Vortex binoculars focus down to 10 feet or less, such as the Vortex Viper at 5.0 feet and Diamondback at 4.5 feet.

Field of View

Important for all binocular users

As you look through binoculars, the field of view is the widest dimension you can see from left to right. As a general rule, the field of view will decrease as magnification increases, so a 10x will usually have a smaller field of view than a 7x or 8x binocular. However, the field of view is actually determined by the eyepiece design, and is rarely a function of the size of the objective lens. You can measure it in one of two ways:

• Linear measurement is in feet at 1000 yards
• Angular measurement is in degrees

Note: One degree is equivalent to 52.5 feet at 1,000 yards.

Tip: A wide field of view makes it easier to find and follow fast-moving action up close. This feature is also desirable for spotting birds and scanning for movement in distant grasslands or dense woodlands.

Interpupillary Distance

Important for fitting binoculars to your face

Binocular barrels rotate around a hinge so a user can line up the eyepieces with eye pupils. When the interpupillary distance is correctly set on a binocular, you will see one circle in the viewing area. The interpupillary distance (IPD) is normally expressed in millimeters and measures the:

• Distance between the centers of a binocular’s two eyepieces
• Distance between the centers of a user’s eye pupils

Full size binoculars work well for the majority of people with IPDs in the 55 mm to 74 mm range. Since compact double-hinge binoculars generally have a narrower IPD, they work well for anyone (including children) who has a very narrow IPD.

Optical Glass Quality

A frequently asked question is, “Why do some binoculars cost more than others?” You’ll find that higher quality binoculars use very dense optical glass that is painstakingly designed, shaped and polished to eliminate flaws and provide better resolution. This labor-intensive process is one reason why binoculars of a higher grade cost more. The customer who desires the best possible image in all lighting conditions will want the highest grade of glass available:

• Standard glass provides good to very good image quality.
• Extra-low dispersion (XD or ED) glass delivers heightened resolution
and color that surpasses standard glass. This rare glass is an expensive
component of fine optics.

Better quality binoculars also have less astigmatism, greater constrast, less chromatic aberration, less distortion, and higher resolution. How this affects image quality is explained here:


This occurs because light rays passing through the curved lens of the binocular do not all converge on the same focal plane. If the overall optical design of the binocular does not remedy this situation, a binocular will provide images where either the center area or the edge of an image is in focus, but not both (without refocusing). Astigmatism can be kept to a minimum, but not completely eliminated.


This is the ability to distinguish differences in brightness between light and dark areas of an image. Optics with superior contrast transmit colors that appear very dense and saturated. Because we see much of the color spectrum, contrast also refers to the ability to distinguish differences in dimensions of hue, saturation, brightness or lightness.

Chromatic Aberrations

This occurs because different colors move through the optical glass at slightly different wavelengths—coming to focus at slightly different lengths. The resulting false colorations (seen most often as purplish and greenish ghost images) diminish resolution and color fidelity. Chromatic aberrations will be negligible with binoculars that use better optical coatings and/or higher quality optical glass.


This occurs when a binocular is unable to deliver a true-to-scale reproduction of an object. There are two main types of image distortion to be concerned with:

• Barrel distortion is where images bow outward and look bulged
• Pincushion distortion is where images bend inward

In both cases, the distortion is due to a lower grade optical design.


This is the ability of the binocular to separate and distinguish thin lines with clarity—essentially the same as image sharpness. The ability to resolve a distant image is a highly desired optical feature.

Anti-reflective Lens Coatings

Each glass surface within a binocular presents a barrier that light must pass through as it moves to the eye. In order to increase the amount of light passing through these air-to-glass surfaces, manufacturers add anti-reflective coatings. The type and number of coatings applied to the binocular lenses greatly affect how brilliant and crisp the image will appear. This factor also helps explain why higher quality binoculars cost more than inferior models.

Anti-reflective coatings work to:

• Eliminate internal reflections and light scattering
• Reduce light loss and glare, bringing the user a brighter image
• Produce sharper images with more detail
• Increase contrast in low light

Levels of Optical Coatings

Coated Lenses

Some air-to-glass surfaces have received an anti-reflective coating.

Fully Coated Lenses

All air-to-glass surfaced have received an anti-reflective coating.

Multi-Coated Lenses

Some air-to-glass surfaces have received multiple layers of anti-reflective coatings.

Fully Multi-Coated Lenses

All air-to-glass surfaces have received multiple layers of anti-reflective coatings.

Note: Look for superior resolution and light transmittance from select Vortex binoculars with proprietary XR fully multilayer coatings.

Measuring Image Brightness

Exit pupil is one of the main indicators of how much light can pass through an optical system.

Exit Pupil

The shaft of light that meets your eye when you use a binocular is its exit pupil. It is seen when you hold the binocular a short distance from your face as a clear circle surrounded by a uniformly dark background.

Why Does the Exit Pupil Matter?

The fixed exit pupil of a binocular limits how much light can pass through the binocular to your eye. When the exit pupil is smaller than the eye pupil, the image will appear dim because the eye pupil could accept more light. When the exit pupil of the binocular is larger than the eye pupil, light that hits the iris is wasted.

Objective Lens Aperture ÷ Magnification = Exit Pupil

Determining the Exit Pupil of an 8×42 Binocular 42mm ÷ 8x = 5.25mm Exit Pupil

A binocular will appear brightest when the exit pupil is equal to, or larger than, the pupil of your eye. The human eye pupil is controlled by the muscles of the iris and can change in size from roughly 2 mm to 7 mm in diameter:

• 2–3 mm in daylight
• 4–5 mm in lower light. Therefore, a binocular with a 5 mm exit pupil is a benchmark to use when evaluating binoculars.
• 6 mm or more in near-dark conditions

Waterproofing and Fogproofing

Waterproof binoculars keep rain and snow from causing internal damage. Fogproofing goes beyond waterproofing by protecting the binocular from the internal fogging that could appear as a customer moves from one temperature extreme to another.

• O-ring seals placed at all open points inhibit the entry of moisture, dust, debris.
• Purging removes atmospheric air from the inside of the binocular and replaces it with an inert gas that has no moisture content—ensuring that binoculars will not fog internally in high humidity or with altitude changes:
· Nitrogen gas purging is commonly used in optics.
· Argon gas is used in select optics—highly prized because it inhibits internal fogging over a wide range of temperatures for a long period of time.

Tip: All Vortex binoculars are waterproof and fogproof for worry-free use in any weather.


Collimation is the mechanical alignment of the optical elements. Exact, precise alignment and locking of the prisms in place is key to producing good quality binoculars and a factor in why some binoculars cost more than others. Binoculars that hold their alignment better are more durable, but even the best binocular can go out of alignment. If a binocular is properly collimated, the horizontal lines should match up correctly. If the binocular is out of collimation, it needs to be repaired.

A Simple Test for Collimation

1. Stand about 15–20 feet from a door
2. Focus on the top of the door frame
3. Carefully pull the binocular away from your face until you start to see where the two exit pupils intersect. Do the two horizontal lines merge, or is one higher than the other.

Focusing Binoculars

Binoculars feature a center focus wheel and an individual eyepiece adjustment ring known as the diopter. Because some people do not have the same vision in both eyes, a diopter will offset the focus so the image is sharp for both eyes.

General Focus Systems

There are three basic types of focus systems on the market today:

• Center focus conveniently adjusts both eyepieces simultaneously with a single focus knob—preferred by most users.
• Permanent focus is normally found on inferior quality models. This system has two drawbacks: The close focus distance is usually 40 feet or more. In addition, there is no diopter.
• Individual eyepiece focus allows for extra-precise focus adjustments. It is often associated with marine or astronomical applications because the focus distance seldom needs to be changed.

The Diopter

The diopter turns to the right and left to make positive and negative adjustments. Some diopters even lock. You will want to note the marking on the numeric scale that is right for you. Then, it will be easy to reset if another person changes the setting.

How to Set the Diopter

Always set the diopter focus for the best focal balance:

1. Adjust the binocular barrels for your interpupillary distance.

2. Using the Center Focus:
With your right eye closed (or with a lens cap over the right objective lens), focus your left eye on an object approximately 20 yards away with the center focus wheel until it is sharp.

3. Using the Diopter:
Adjust for your right eye, but do not change the center focus. Close your left eye (or place a lens cap over the left objective lens) and focus your right eye on the same object 20 yards away—only using the diopter.

4. From now on, you only need to use the center focus wheel.

Choosing a Binocular

First off, there is no right or wrong binocular—only better matches between everyone’s unique viewing needs. Consider how you will be using the optics Nature watching? Hunting? Boating? Astronomy? Looking at a bird feeder from a window? Taking on long hikes? Heavy use in low light?”

Consider the Magnification

Binoculars are available in a wide range of magnifications, but 8x and 10x binoculars are very popular choices for nature observation.

8x Binoculars

For birding or general nature watching and woodland hunting, 8×32 or 8×42 binoculars are likely good choices. If the observation is done primarily at close range, such as in woodland areas or in your backyard, then an 8×42 binocular is probably the best choice. This magnification generally provides a wider field of view, which is especially important for viewing objects relatively close at hand. In general, 8×42 binoculars perform better in the low light of dawn and dusk. This magnification also works well at sporting events where the wide field of view keeps the action in the viewing area.

10x (and Higher) Binoculars

Hunters glassing from long distances and bird watchers observing raptors or shorebirds often desire the extra magnification of a 10×42 binocular. However, since hand tremors are magnified along with the image, some find binoculars of 10x or higher are more usable with a tripod.

Tip: Keep in mind that a 10x binocular usually has a narrower field of view than an 8x binocular in the same series.

Consider the size

Binoculars fall into one of three general size categories depending on the size of the aperture. Your personal preference and the intended use of the binocular will both come into play when selecting a binocular.

Compact Binoculars

Binoculars with objective lenses measuring 28 mm or less can be so compact that they may fit in a pocket. Though such a binocular gathers less light than other sizes, it is a fine choice when a portable binocular is needed for viewing during the day.

Mid Size Binoculars

Binoculars with objective lenses measuring from 30 mm to 36 mm fall into this category. Many users find this is a nice compromise between size and light gathering ability.

Full Size Binoculars

Binoculars with objective lens sizes measuring 42 mm and greater fall into this category of binoculars. While a full size binocular has the ability to gather more light for the optical system ability, the trade-off is that the binocular is larger.

Lines of Vortex binoculars

Razor HD

Reach for the pinnacle of high-performance optics with the Razor HD—completely redesigned for 2011.

Viper HD

Our Viper HD binoculars pack in the features you need for a successful hunt or bird-watching hike—see what premium optics can do for you. Now in 2011, our award winning Vipers come with HD (High Density) glass.

Talon HD

The Talon HD puts glassing of all kinds right at your fingertips with a sleek, ergonomic open-hinge design.


Superior quality, high-performance optics can find their way around your neck for a surprisingly affordable price.

Crossfire II

Step into the world of optics and let Vortex pleasantly surprise you.

Not all available binoculars are listed on our website. If you want a pair you do not see listed, please call.

To order or to discuss your optic needs with us, please call 1-877-434-0765.

Thank you for choosing Nature Friend to assist you with your optic needs.