Binoculars Buying Guide: 4 Steps to Choose Your Best Binoculars
So you've decided to explore this exciting world 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 and buy 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?
When looking around for binoculars, you can find so many options in wide range of prices. Binoculars with higher prices will offer you high quality, crisp image with a comfortable, durable design. Lower price ranges usually involve a trade off between size and image quality.
For beginners, something like a 6x32 or 8x42 binoculars around the US$150-200 price range could be the most versatile option.
Understanding the specifications and features, like magnification, objective lens diameter, prism types, will help you find the binoculars that work best for your needs within your budget.
2. WHAT DO THE TERMINOLOGIES MEAN, AND WHY SHOULD YOU CARE ABOUT THEM?
When shopping around for 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. Generally speaking, 8x or 10x is the best 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 tripod 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 bigger objective lenses (15x70, 20x80, 25x100, etc.) that demands a mount while binoculars for birdwatching, hunting, 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 is another important factor that affect the image quality of your binoculars. There are thousands of different formulations of glasses, each has its own 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 similar K9) is a type of glass that has been widely used across many optical equipments. BK-7 and K9 glasses are in lower cost and performance than BaK-4, and therefore are usually used in low/mid-end binoculars.
BaK4 is much more expensive than BK-7 or K9 glasses, usually found in high-end binoculars, spotting scopes, and monoculars. BaK-4 is generally preferable to BK-7 or K9 as it has a higher refractive index and provides higher levels of image quality.
Always check the product specifications to discover the type of prism glasses.
There are two prism types for binoculars: "porro" and "roof". Porro is an older prism design with a simpler light path, it provides relatively better image quality and lower cost, but makes the binoculars bulkier, heavier, and harder to waterproof. Binoculars with 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 while roof binoculars for birding/hunting and event applications.
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 preferable, especially for those who use binoculars with eyeglasses.
Generally speaking, binoculars with higher magnifications and larger fields of view have shorter eye relief. Binoculars with both high magnifications and long eye relief may be available, they just cost more with better optics design. Eye-cups on the binoculars protects the lens from the naked eyes but, when twisted/folded down, allows eyeglass-wearers to get closer to the optics to make up for the eye relief.
This is the aperture that the light leaves the optics and enters your eyes. Ideally the exit pupil should be equal to your eyes' pupil diameter so that light is neither lost or vignetted. The pupil diameters change with age (smaller over time): A 20-year-old's pupil size ranges from 4.7-8mm while a 70-year-old's pupil size ranges from 2.7-3.2mm.
Optics coating protects the glass from the elements and reduces light reflections and glare, This is an important feature that makes noticeable differences in the quality and brightness of your image. It certainly something to look out for when buying binoculars, and you should be aware of the precise wording.
- Coated – means a SINGLE layer of anti-reflection 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 anti-reflection coatings;
- Fully Multi-Coated – means that ALL air to glass surfaces are coated with MULTIPLE layers of anti-reflection coatings. This is the best coating usually found in high end binoculars.
"Fully Multi-Coated" (FMC) optics produces highest image quality, and are consequently more expensive. Lower priced binoculars are usually only Fully Coated or Multi-Coated.
ED & APO Glasses
Binoculars using ED(extra-low dispersion) glass can greatly reduce the color fringes ("chromatic aberration") in high-contrast (bright against dark) scenes 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, usually used in large astronomical optics.
This affects the durability and weight of your binoculars.
Polycarbonate plastics are often used in low priced binoculars, but this does not make them bad since it is easier to waterproof and to keep the optics 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?
Binocular sizes are categorized as below based on the size of their objective lenses:
- Full Size: with objective lens diameter greater than 40mm (Such as 8 x 42, 10 x 50)
- Mid-size: with objective lens diameter between 30mm and 40mm (Such as 6 x 30, 8 x 32)
- Compact: with objective lens diameter smaller than 30mm(Such as 8 x 25, 10 x 25)
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 little bit too big and heavy for backpacking.
Mid-Size is a great choice for on-the-go wildlife and sports viewing, where conditions will usually be bright.
Compact binoculars are easy to carry, preferable for daytime outdoor activities like backpacking, but they often delivers lower image quality, and are less comfortable during longer periods of use.
Then it comes to the ultimate question:
4. WHAT (WHERE) WOULD YOU USE YOUR BINOCULARS FOR?
Hunting? 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 8x magnification are great for viewing wildlife at a distance, while for stargazing it will be better with a 15x or similar.
Check out this Recommendations on Binoculars for Outdoor Activities.