Buyers Guide for Choosing Your Binoculars
So you've decided to explore the exciting world of binoculars and look for the best binoculars for your next outdoors adventure? Choosing the perfect binoculars are often intimidating with the various specifications and features. This binoculars buying guide will help to pick for the best binoculars to utilize in a wide-variety of outdoor activities. Whatever your passion, you’ll be able to find an excellent pair of binoculars to enhance your experience.
Some key questions you should consider before buying your binoculars:
1. WHAT’S YOUR PRICE RANGE?
Binoculars with higher prices will offer you an ideal, crisp image with a comfortable, durable design. Lower price ranges also have some great options, but usually involved with a trade off between size and image quality.
When buying binoculars, you can also find binoculars in wide range of prices. Understanding binocular specs, like magnification and objective lens diameter, will help you find out which binoculars work best for your needs.
If you are just getting started, something like a 6x32 or 8x42 in the US$100-150 budget may be the most versatile option.
2. WHAT DO THE TERMINOLOGIES MEAN, AND WHY SHOULD YOU CARE ABOUT THEM?
When looking around the binoculars, you might be confused by some of the jargon. Understanding the most important terminologies listed below can help a lot for choosing your best binoculars:
Magnification and aperture: These are the most important specifications for binoculars.Common examples you see include 6x32, 8x42, and 10x50. The first number refers to the magnification, i.e., the proportion that your binoculars enlarge your target. The second number refers to the aperture, or the diameter of the objective (front)lenses (in millimeters). Greater magnification takes you "closer" to the target but too much magnification can produce shaky views when holding with hands. Magnification also magnifies your hand shake: 10x is generally the golden magnification for most people’s tolerance when hand-holding though you may be able to get away with 12x or 15x with steady hands or mechanical stabilization with a monopod or bracing yourself. Bigger aperture allows your binoculars to collect more light to improve the brightness and quality of your images, but makes the binoculars heavier and more expensive. Amount of light gathered by binoculars scales with the square of the object lens diameter: a 50mm aperture gathers twice the light of a 35mm and four times that of a 25mm. The right combination will depend on your use case: binoculars for astronomy often tend towards more magnification and aperture (15x70, 20x80, 25x100, etc.) that demands a mount while binoculars for birdwatching, animal watching, and other outdoor adventures should be lightweight with lower magnification (5x25, 6x32, 8x42) so that you can hold them comfortably in hands.
Field of view:The field of view (FOV) is the amount of a scene the optics can take in. For binoculars, this can be described as either an angular or a linear field of view. An angular field of view is specified in degrees and for most binoculars is in a range between 4° and 8°, higher magnifications often come with smaller FOVs and lower magnifications having higher larger FOVs. A linear field of view is specified as a ratio, e.g. "298ft/1,000 yards" or "88m/1,000m" which means that you could see 298 feet/88 meters of width and height of an object 1,000 yards/meters away. Angular measurements are more common for astronomy and linear measurements are more helpful for travel, nature, events, or security.
Inter-pupillary distance (IPD):This is the distance between the centers of the pupils of your eyes, typically measured in millimeters. This distance varies for everyone from 50s to 70s with an average around 60mm. If your IPD is smaller or larger than a binocular's designed range, you will not be able to use the binoculars comfortably. You will want to measure your IPD either by yourself or at your next eye appointment so you know what kind of binoculars to look for.
Prism Glass:There are thousands of different formulations of glasses, each has its own very specific optical properties and designations. BK-7 and Bak-4 are two of the most common designations of glass formulations used in the prisms of binoculars, spotting scopes, and monoculars.
BK-7 (as the very similar K9) is a type of borosilicate glass that has been widely used across many different optical product. BK-7 and K9 are in lower cost and performance than BaK-4 and therefore are usually used in lower priced products.
BaK4 refers to a light barium crown glass that much more expensive than BK-7 or K9 glasses, usually found in high-end optical instruments. For binoculars, spotting scopes, and monoculars, BaK-4 is generally preferable to BK-7 or K9 as it has a higher refractive index and, when used in a well-designed overall optical system, provides higher levels of image quality than would a prism assembly of the same type made with BK-7 or K9 glass. It is commonly known that the exit pupil of a BK-7 or K9 prism is not perfectly round as a BaK-4 prism, which causes clarity issues on the edges of the image. Always consult the product specifications to discover the type of glass used in the system’s prisms.
Prism Type:There are two prism types for binoculars: "porro" and "roof" prisms. Porro prisms are older design with a simpler light path that relatively provides better image quality and lower cost, but tend to be bulkier, heavier, and harder to waterproof. Roof prisms are more compact, lighter weight, and easier to waterproof, which makes them more durable but also more expensive. A porro design is generally recommended for astronomical applications and roof prisms for birding/nature/animal watching and event applications.
Eye Relief:This is the distance from the exit of a binocular where the full viewing angle can still be obtained. "Longer" eye relief (>10mm) is almost always desirable, especially for people who use the binoculars with eyeglasses. Eye relief cannot be easily computed from other specifications, but binoculars with higher magnifications and larger fields of view generally have smaller eye relief. Binoculars with both high magnifications and long eye relief may be available, they just cost more. Eye-cups on the binoculars protects the lens from the naked eye but allows eyeglass-wearers to get closer to the optics to make up for short eye relief.
Exit Pupil:This is the aperture that the light leaves the instrument and enters your eye. Ideally the exit pupil should match your eyes' pupil diameter so that light is neither lost or vignetted. Your eyes' pupil diameters change in the day (smaller) versus the night (larger) as well as with age (smaller over time): A twenty-year-old's pupil diameter ranges from 4.7-8mm while a seventy-year-old's pupil diameter ranges from 2.7-3.2mm.
Coating applied to optics protects the glass from the elements and reduces reflections and glare, the level of lens coatings can make noticeable differences in both quality and brightness of the image. This is an important feature and certainly something to look out for when buying binoculars, and you should be well aware of the precise wording.
* Coated – means a single layer antireflection coating is applied on some lens elements, usually the first and last elements;
* Fully Coated – means that all air to glass surfaces are applied with single layer coating;
* Multi-Coated – means that at least some surfaces (usually the first and the last) are applied with multiple layers of antireflection coatings;
* Fully Multi-Coated – means that all air to glass surfaces are coated with multiple layers of anti-reflection coatings.
Lower quality binoculars will only be Fully Coated or Multi-Coated.
Optics that are "fully multi-coated" produces highest image quality, and are more expensive. There was a time when you could only find fully multi-coated binoculars at the top end product lines, but now as the production method improves, you may also find it on some mid-end binoculars.
ED & APO
Binoculars using extra-low dispersion (ED) glass can reduce the color fringes ("chromatic aberration") in high-contrast scenes (bright against dark) but this glass is only found in the most expensive optics.
Apochromatic ("apo") lenses offer the best correction of chromatic and spherical aberrations, but they are heavy and expensive compared to achromatic lenses and rare to find outside of large astronomical optics.
Polycarbonate plastics are often used in the least expensive binoculars, but this does not make them bad since it's also easier to waterproof and for the optics to remain well-collimated;
Aluminum chassis provides a better feeling of substance and quality to binoculars, but also makes the binoculars heavier;
magnesium is found in the highest-end binoculars, as it provides high strength and low weight (ruggedness and portability) at the same time.
3. DOES SIZE MATTER?
Here are some common size categories to help you out:
- Full-Size (Such as 8 x 42, 10 x 50) - Full-size binoculars capture more light and work better in low-light situations. They are best for serious wildlife viewing or for use on boats, but probably too big and heavy for backpacking.
- Mid-Size (Such as 7 x 35, 10 x 32) - This is a great choice for on-the-go wildlife and sports viewing. If you like to attend outdoor events, you can skip binoculars with large objective lenses as conditions will usually be bright and ideal for viewing.
- Compact (Such as 8 x 25, 10 x 25): These are best for daytime outdoor activities like backpacking, but they’re less comfortable during longer periods of use. If you’re after more compact binoculars for traveling, or want a more child-friendly option, then you might want to pick a pair that has a lower image quality, but is lighter due to a smaller lens size.
Then it comes to the ultimate question:
4. WHAT (WHERE) WOULD YOU USE YOUR BINOCULARS FOR?
animal watching? boating? stargazing? backpacking? outdoor hiking? traveling? concert, theater and sport spectating? bird-watching?
You would need different binoculars (magnification. size, weight...) for different purpose. For example, binoculars with 10x magnification are great for viewing wildlife at a distance, while for stargazing it will be better with a 20x or similar.
Check out this Recommendations on Binoculars for Outdoor Activities.