While you should choose the best birding binoculars you can afford, you can begin with a simple, inexpensive pair. As your bird watching hobby progresses past casual interest you may want to upgrade to better quality. But no matter whether you are beginning or are a more experienced birder you should have a basic understanding of birding binocuars so you can select those that are best for your style of bird watching.
To help reduce the difficulty and confusion that arises around selecting the right binoculars, you'll find help here. While watching birds may be the most demanding use of binoculars, the same basic principles, terms and definitions regarding all binoculars apply to those appropriate for bird watching. The factors determining the best choice among birding binoculars vary with the quality and design of the binocular, as well as the conditions under which they are used, and the preferences of the birder using them.
Why are birders considered the most demanding users of binoculars? Because they not only must spot birds but must also identify them. Birding binoculars must deliver good results:
- Birding binoculars must provide very sharp views so fine details can be seen.
- Birding binoculars must perform in all kinds of weather conditions, and at all hours of the day and night.
- Birding binoculars must provide the ability to view an image quickly.
- Birding binoculars must be able to deliver the best view in all conditions.
Note: My recommendation for the best selection and best prices is Eagle Optics: The source for binoculars, spotting scopes, tripods and accessories since 1986! I purchased my binoculars from them and the experience was excellent. They are the perfect company to do business with and even have a 30-day money-back satisfaction guarantee. My binoculars are Stokes Birding Series DLS 8x42's (also available in 10x42). Learn more about my binoculars.
What's With All Those Numbers and Techno-Terms?
There are some factors to consider in choosing the best birding binoculars to fit your preferences and needs. Here are some descriptions and specifications you should understand before selecting your binoculars ...
Viewing Your Subject
Power
- Objects appear larger with increased power (magnification) providing more ability to see detail like field marks. Binocular magnification is determined by numbers. In this example, the first number (8) in 8x42 binoculars make the image 8 times larger to the naked eye. The second number (42) refers to the diameter in millimeters of each front objective lens. A larger diameter objective lens gathers more light, provides better detail, a cleaner image and larger field of view. However, a larger objective lens adds more weight. How large a lens you need depends on how much magnification you require.
- With increased magnification it becomes more difficult to hold your binoculars steady, you'll have a narrower field of view and less depth of focus, brightness and clarity diminish, and heat wave distortions become more noticeable. There are tips for holding binoculars steady but there may be some recommended powers (i.e. 10x) that are still too difficult for some people to manage.
- Choosing a lower magnification than 7x or 8x may sound appealing because of their smaller size and lighter weight. But these smaller binoculars have a small, darker and narrower image making them much less desirable for birding. The recommended magnification for birding is 7x or 8x.
Field of View
- FOV means the width of the scene that can be viewed at 1,000 yards (or meters). It is easier to find birds with a wide field of view. For instances, if you scan the sky for hawks, flocks of shorebirds on the mudflats, or birds in flight you may want to consider binoculars with a wider field of view. But there are trade-offs. With a wider FOV you will lose some ability to resolve details. Also, a too-wide FOV often results in distortion at the edges of your image. All factors being equal lower magnification means wider field of view. The recommended minimum field of view is 300 feet at 1,000 yards.
Exit Pupil
- This is the size of an image at the binocular's point of focus. The exit pupil's ratio should be between 4 and 5 which provides a brighter image. Interestingly, a 4 to 5 ratio also means it is easier for your eyes to remain on the image when it is bright out and your pupils are contracted. If the exit pupil is below 4 there won't be enough light gathered to support the amount of magnification so the image will be dark and indistinct. This is less of a problem on a very bright day.
- An exit pupil is determined by dividing the object lens size by the magnification power. Using my 8x42 binoculars as an example, you'd divide 8 into 42 with the result of 5.25, a good exit pupil ratio. Complete details on my binoculars.
Eye Relief
- This is the distance behind the occular lense at which the image is in focus. In other words, it is the distance between your eyes and the lens you look through when your image is in focus. Eye relief is especially important to people who wear glasses. Eyeglass wears can't get their eyes as close to the occular lenses so the full image can't be seen. Binoculars with eye cups that can be folded down or adjusted by rotating in and out provide sufficient eye relief so the eyeglass wearer can see a full image. Binoculars with at least 15mm eye relief is considered sufficient. Long eye relief usually reduces the field of view.
- If you currently wear glasses because you are nearsighted or farsighted you can use your binoculars without your glasses. The focusing capability of the binoculars will compensate for the removal of your glasses. However, if your glasses correct for astigmatism you will need to wear your glasses with your binoculars so those offering good eye relief becomes especially important.
Close Focus
- Improvement in optics now give us the opportunity to buy binoculars which can sharply focus on objects at 10 feet or less ... the with champ focusing at 3 feet! Since all binoculars focus at infinity, consideration should be given to how close you can focus with them. The need to close focus comes into play more often that you might realize. It is also important for birders that might also enjoy watching butterflies ... another fast-growing hobby. Good birding binoculars should be able to focus at 10 feet or less. Mine focus at 4.5 feet.
The Binocular Lenses
Objective Lenses
- Objective lenses are the large lenses that gather the light. More light gathering capability means seeing more detail. Since birds are more active when the light level is low, as it is in early morning and late afternoon, more light gathering capability means more quality birding time.
Prism Glass
- Prisms refer to the mirrors within the binocular. There are two types of prism glass primarily used today. They are BaK-4 and BK-7. The labels refer to the element used to modify the composition of the glass used in the mirror. "B" is Boron and "Ba" is barium. The Bak-4 prism is better and more expensive. BaK-4 is a high density glass and provides a sharper image. The coatings used on the prisms are also of primary importance (see Coatings below). Binoculars with BaK-4 prisms will usually say so in the specifications. If BaK-4 is not listed then assume the prisms are BK-7.
Coatings
- Coatings refer to optical coatings applied to the prisms and lenses of the binocular. Both prisms and lenses are coated. The main reasons for using them are to reduce internal reflections and improve light transmission. Optical coatings are extremely important to deliverig a sharp and bright image. There are different types of coatings and they are applied as a single coat or in layers. Each layer of coating improves the image, but also adds cost.
Coated (C) - Refers to a thin anti-reflective coating (usually Magnesium Fluorite). It is deposited on one or
more of the lens surfaces.
Fully Coated (FC) - Refers to at least one thin anti-reflective coating. The coating is on both sides of the
objective lenses, both sides of the occular lenses, and the long side of the prism.
Multi-coated (MC) - With this type of coating one or more of the lens surfaces have multiple coatings.
Fully Multi-Coated (FMC) - This type of coating is usually applied to the top-of-the-line optics and refers to all
lens surfaces having multiple coatings. While this indicates greater care has gone into the design of the product,
it does not necessarily guarantee the best quality. Quality is determined by the way the total product has been
manufactured.
Selecting a binocular is a highly individual choice, of course. But go for the highest level of lens coating you can afford. This is especially true if your eyes are susceptible to glare or you're approaching the age of 50.
The Binocular Body
Porro Prism or Roof Prism Design
- Porro prism binoculars are the familiar offset barrel style. The roof prism binoculars are the sleeker straight barrel style that have been available more recently (see photo on page 1). Porro prisms are more bulky, a little heavier and are harder to weather-proof. Their advantage is a wider field of view (FOV) and they are less expensive so offer the same optical quality for less money. The roof prism models are more tolerant of rough treatment with less chance of the lenses becoming mis-aligned. Even though roof prisms cost more, their ruggedness may pay off in the long run making them more cost effective.
Weight
- Weight of binoculars can be a factor. But is is probably one of the least important aspects of choosing them. Today's construction materials are lighter and stronger. Unless you are very experienced, most people wouldn't be able to tell the difference between a binocular that weighs 28 oz. or 32 oz. even after a long day of birding. If you do your research you'll discover a range of weight specifications for binoculars of the same class. A more important aspect than the binocular's weight, is it's balance. One that is well-balanced puts very little stress of arms, wrists and hands. A poorly balanced pair will cause more stress even if it is lighter in weight.
Ease of Focusing
- When it comes of focusing the key is speed and precision. You don't want to miss the bird because you can't get it in focus quickly. Ideally, you want the focusing mechanism to go from close focus to infinity in a full turn (360 degrees) with a variable speed focusing gear. This mechanism allows focusing slower when the image is near, and faster when farther away.
- Equally important is the depth of focus. Binoculars that have a shallow depth of focus will take extra effort to get a sharp image.
Eye Cups
- Eye cups help eliminate light that would affect our vision while using binoculars. They also help to measure the distance from the occular lens to our eyes (discussed in Eye Relief on page 1). Eye cups were first made of rubber. To get eye relief when wearing glasses the eye cups were rolled up or down. The downside was the breakdown from repeatedly rolling the eye cups. The first advancement in eye cups were those that slide in and out. The problem with this is the difficulty of keeping them in place. The next improvement came with eye cups that twist up and can be left at any position. The newest, and the best are those that have click stops at intervals in the up-down path. The eye relief distance for each stop is marked on the eye cup.
Protection for Binoculars
Weather-proofing
- There is a range of weather-proofing available. However, some binoculars offer no water-proofing at all. Other choices are shower-proof, water-proof, or nitrogen purged. The water-proof type of sealing is accomplished with "O" rings. Nitrogen-purged water-proofing is a must for active birders whether they are in a humid climate or not. Binoculars that are nitrogen-purged will also keep out dust, sand, or anything else that can get inside and harm the binoculars.
External Protection
- The synthetic rubber that offers binoculars external protection is known as armoring. It protects the body of the binocular from banging and bumping and some corrosive elements.
The Cost of Binoculars
- The price range of birding binoculars ranges from quite inexpensive to scary. Simple, inexpensive binoculars can be purchased for as low as $50 or so. This price level is where some birders begin and they still work in some instances. If you think your bird watching interest will remain casual or your eyes are very young these simple binoculars may be all you need. The next level ranges from $100 to $250 or so. Many people find the binoculars in this price range satisfactory for a lifetime of birding even if they become slightly obsessed.
- Binoculars in the $500 to $1,500 or so price range will bring bird images up close and personal with a degree of clarity that rivals those half-million dollar cameras used for Super Bowl Sunday. A word of caution ... don't sneak a peek through someone's top of the line optics if you intend to purchase moderately-priced binoculars. You'll never want to go back!
