Choosing The Right Pair of Binoculars, the Essential Guide for Hobbyists
Binoculars are optical instruments for observing and magnifying images of distant objects. A binocular is essentially made of a pair of low power telescopes side by side. While binoculars normally have lower magnification power than telescopes, they nonetheless have some distinct advantages too. For one, a binocular has two eyepieces, allowing for more natural observation of images as the brain is better able to resolve details of an image when both eyes are used to observe. Moreover, each of the instrument’s chambers is fitted with a prism which corrects the incoming image for observation the right side up (a telescope shows images upside down).
• What to Consider Before Shopping for Binocular:
• The most essential factors to consider before shopping for a suitable pair of binoculars
• What you’ll Use the Binoculars For
Binoculars are used for many hobbies including bird-watching, hunting, astronomy or observing the action at concerts and sporting events. Different features and specifications of specific binoculars render them either effective or unsuitable for particular hobbies. As such, you need to carefully consider what you will be using your binoculars for before embarking on shopping for one. For instance, if you are going to be using your binoculars mainly for astronomical observation, you need a pair with deep focusing ability as the objects you will be observing will be millions or even billions of kilometers away from you. While it is always important to look for binoculars with good waterproof construction, this becomes even more important when shopping for binoculars you will be using on boating trips.
Magnification:
The magnification power of a pair of binoculars (or any optical instrument for that matter) is arguably the most telling feature of its suitability for a particular purpose. It does not always follow that the higher the magnification, the better the binoculars are. Needless to say, higher magnification means the binoculars are great for observing distant objects. High magnification binoculars are recommended for observing still objects at a distance though you may need to use tripods if the object is too far away. A tripod will help reduce the amount of shaking which results in blurred images. However, binoculars with high magnification also mean the image is often darker if the light is low, and the field of view is much narrower. Lower magnification binoculars do not offer much detail for distant objects. However, the image is usually brighter and wider. They are also better suited for viewing moving objects such as birds.
The magnification power of a binocular is usually expressed in combination with the binoculars’ objective lens diameter. As such a 10X25 binocular has a 10 power magnification and a 25 millimeter objective lens. In general such a binocular is considered a compact sized one. A medium size binocular will have an objective lens of about 32 millimeters while a full size pair of binoculars will often feature 42 to 55 millimeter objective lens.
Coatings:
Theoretically, two binoculars with similar sized lenses should have the same ability of collecting light from distant objects. However, it is common to find that two binoculars in the same objective lens class show varying amounts of brightness for the same object. Why? It has everything to do with the coatings on the surface of the lens. When light passes through a bare lens, up to 5% of the light is reflected off the surface and lost. By the time the image reaches your eyes, about 35% of the light will therefore have been lost. With effective multiple coating layers, the lens will reduce the amount of lost light in each lens to about 0.5% guaranteeing only about 5% loss in brightness.
You may come across some binoculars being promoted for having ruby coatings. The ruby is a reference to color, not the type of material the coating is made of. The use of ruby coatings is intended to remove red light from the image which often leads to chromatic aberrations. However, the end result is usually that the image gets a distinct blue-green cast. What is more, ruby coatings are usually very reflective and can greatly reduce brightness. For most purposes, ruby colored binoculars are not suitable options.
Prism Design:
When it comes to prism design, you have a choice between porro prism and roof prism binoculars. The pooro prism design was the standard for quality binoculars up until the 1960s. In recent years, this classic design has been replaced with the roof prism designs pioneered by Zeiss and Leitz companies. These tend to be lighter, compact and more intuitive to use compared to binoculars with porro prisms. This does not mean that porro prism binoculars are obsolete though. Dollar for dollar you might find that the best value for money comes from a porro prism binocular especially if you are shopping on a budget.
Field of View and Exit Pupil Ratio:
The field of view and exit pupil ratio are two important pointers for determining the quality of a pair of binoculars. The field of view is a number expressing how wide an area is encompassed in the binoculars’ image. The field of view can be expressed as an angle or as the width in feet of the image at 1000 yards (420 feet). As you can tell, the higher the magnification power of a binocular, the narrower the field of view. The exit pupil ration is the fraction you get when you divide the objective lens with the binoculars’ magnification. For instance a 7×42 binocular has an exit pupil size of 6 millimeters. Under normal daylight conditions, the human eye’s pupil is around 2 millimeters and therefore exit pupil ratio is not too much of a factor for daylight viewing. However, as daylight fades into night, the pupil size can extend up to about 7 millimeters, making viewing through small exit pupil ratio binoculars cumbersome.
Durability and Waterproofing:
Being tools you will be using outdoors, it is imperative that you get a pair of sturdy, durable binoculars. While portability may seem like a good consideration, if your binoculars are too light, this may indicate poor quality of materials and construction. Just as well, good binoculars should be waterproof. If water sips into the lens and prism assembly, it can be very difficult to get rid of it. Make sure you understand the difference between water resistant and waterproof.
Your Budget:
Ultimately the most versatile and functional binoculars are the costliest. The cost of a particular pair of binoculars will depend on the combination of features it boasts of as outlined above. For instance, binoculars with BK-7 lenses are normally costlier than those fitted with BAK-4 lenses. Just as well, binoculars with deep focus ability will be costlier than those with much closer focusing power. There are two lessons to take home from this. One, it does not always follow that the costlier a pair of binoculars are the better they for your needs. Secondly, if you take time to learn about binoculars and your hobby interests, the better will you be suited in identifying a pair of binoculars that is ideal for your purposes within the limits of your budget.
