It is no surprise that binoculars have simplified the lives of a multitude of individuals, including hunters, birdwatchers, zoologists, campers, law enforcement, and border control. It is undoubtedly one of the many important inventions of the twentieth century. Although all binoculars are essentially used to view distant objects up close, the truth is, not every pair of binoculars is designed to be used for all observations.
The most common use of binoculars is in hunting, where experienced hunters use binoculars to observe animals from an acceptable distance. Most wild animals have evolved to be very much aware of their surroundings and even a slight hint of a hunter’s presence is enough for them to run or hide. To deal with this problem, hunters make use of binoculars to avoid getting close to the animals until they are confident enough of their shot. The focusing mechanism on binoculars made for hunting is usually called slow-focusing.
Since hunting has become a widespread sport, most binoculars sold today are specifically designed to aid hunters in their exciting adventures. For this, modern binoculars have several features included so as to help the hunters in their day-long adventures, such as large objectives, a precise focusing system, an ergonomic grip, neck, and shoulder straps, and robust rubber armor for protection from accidental falls.
Although the use of binoculars has become popular among hunters, the truth is that beginner hunters are still not familiar with the correct use of the most important feature of binoculars, that is, the focusing mechanism. Even the cheapest and general-purpose binoculars come with an installed focusing system, which needs to be adjusted while the hunter tries to fixate on a distant wild animal. Nevertheless, most hunters, especially first-timers, do not know what features make up the perfect focusing mechanism in a set of binoculars.
Usual conditions when hunting
Hunting is mostly carried out in the woods or rough mountainous terrains since most animals like deer, wild boar, rabbit, and others can be found there. These areas are notable for highly unpredictable weather since it is not uncommon for hunters to face a colder climate and out-of-season rains. This is the reason why people always prepare the appropriate gear before embarking on their wild hunting excursions.
While some animals are considered to be slow-moving, most game animals move relatively fast and hunters have to remain alert and predict their likely path. Some hunters prefer driven hunts instead, which usually does not require binoculars.
Most animals have a camouflaged outer appearance which enables them to hide in their surroundings away from predators and humans. To not overlook such animals, hunters require binoculars that provide a great deal and bright images. This is where larger objective lenses and a precise focusing mechanism come to the rescue. Additionally, gas purging plays an important role in keeping the binoculars from becoming a victim of internal lens fogging in the highly-humid rainy and cold weather of the wilderness.
Most binoculars today either come with a central focusing mechanism or a focus system that is separate for each eye. Both of these focus systems are discussed below in detail:
CF or Center Focusing is the most common type of focusing system available in hunting binoculars nowadays. This was the first mechanism that was originally introduced in the earliest binoculars due to its simplicity. The mechanism has evolved over the years to provide effective focusing capability but the basic idea has remained the same.
To focus on a distant object, the hunter needs to turn the focusing knob several times for a small amount of focus adjustment. This provides greater control of binoculars for the hunters since they can view greater details of objects. Wild animals possess excellent camouflaging capabilities and identifying them from a distance is close to impossible. Precise control of the focus knob enables serious hunters to spot and identify game easily without having to be nearby.
This is another opportunity for innovation for optics manufacturers. Since hunting binoculars are frequently used in rainy and cold weather in the tracking of animals, the central focusing system has to be designed in such a way that it provides a smooth grip of the focusing knob, even in wet weather. Additionally, most hunters prefer to hunt with gloves on, and for a day-long adventure, the binoculars, as well as the focus wheel, must provide a comfortable grip.
Since most animals that the hunters hunt move slowly and hunting itself is usually a waiting game, the important thing for the Central focusing mechanism on binoculars meant for hunting works as slow and as precise as possible. This means that the hunter can do very fine adjustments of the focus to get the best possible details recognition as possible. Usually, such binoculars have a very big total travel of the focusing wheel, and the user has to do many turns of the wheel to come from one extreme focusing position to another. This is completely the opposite of what birdwatchers need when observing birds that usually move very quickly compared to bigger animals.
Zeiss Sports Optics has recently introduced the Smart-Focus or SF Concept in its Victory series of binoculars. This concept features the focus knob placed in the center on a triple-link bridge design for a comfortable alignment with the usual position of the index finger. This makes it possible to use and focus the Zeiss Victory SF binoculars with only one hand. Also, the focus wheel used in this design is comparatively larger than what is seen on standard binoculars. The large wheel offers a smooth grip and precise control of the focus adjustment, enables users to pinpoint details on varying distances comfortably. Popular brands like Leica, Swarovski, Nikon, and others have similarly introduced comparable focus features in their flagship binoculars series to facilitate the users.
Center focus systems are popular among hunters because they can be adjusted precisely. Also, these binoculars can be shared among groups on hiking and camping trips since turning one knob is easier than having to adjust both barrels.
Although superior in several ways, binoculars with center focus suffer from ineffective waterproofness. Both barrels in CF binoculars are interconnected and adjusted simultaneously, which makes it a little challenging for binoculars manufacturers to achieve an ideal fog-proof and water-proof capability. As a result, these binoculars will likely develop Nitrogen leak than their Individual Focus counterparts in case of a hard fall.
Focusing separated for each eye
A relatively newer focusing mechanism in binoculars, the Individual Focusing (IF) system, allows users to adjust the focus of each barrel individually irrespective of each other. Instead of a center knob, binoculars with IF systems have dioptre rings on both barrels, which can be adjusted one-by-one irrespective of each other.
One of the advantages of a set of binoculars with an IF system is that it needs to be adjusted only once, unlike its Center Focus counterpart, which needs to be adjusted every time the user jumps from one object to another. You can adjust the binoculars as you look through the eyepiece by turning the dioptre (focus) rings provided on each barrel sequentially. Since each barrel can be adjusted separately, the binoculars can be set to achieve razor-sharp images every time. Once the focus is set for a particular user, the adjustments are made by the eyes themselves. For this reason, IF binoculars are sometimes called Fixed Focus binoculars.
Additionally, people who wear prescription glasses can use the binoculars without their glasses to improve minor visual acuity difference between both eyes. This is done if the dioptre adjustment is set to match the differences in vision impairment.
Another advantage of IF binoculars is their waterproof capability. Since the barrels are not interconnected, the optics housing can be secured more effectively and there is a lesser chance of gas leakage. This way the nitrogen-purged optical compartments of the binoculars are not susceptible to damage from internal fogging.
The individual focus system is best suited for use in low light hunting situations, especially during the dawn, when most hunters prefer to start their day. With individual focus, the hunters can spot and focus objects even in minimal light. Paired with Porro prisms, the low light capability of such binoculars is further enhanced.
On the other hand, the individual focus is not appropriate for use in other forms of hunting, especially when hunters may have to pursue game on foot. Additionally, the close focus on IF binoculars is usually longer which inhibits their use on distances shorter than 10m. Another disadvantage of such binoculars is the lack of adjustable eyecups on the eyepiece – most IF binoculars may have retractable rubber eyecups that offer no flexibility.
Experienced hunters prefer binoculars that have a steady and precise focus. Visual information plays an important in hunting since they help hunters in locating and identifying animals from a distance. A precise focus adjustment is usually achieved by using a large focus wheel which is turned several times for a small change in focus. As a result, the observer can perceive minute details of the object and can take an informed shot. The opposite of this is true for birdwatchers, who need quick focus adjustments to observe unpredictably fast-moving birds.
Two types of focus systems are available in binoculars nowadays. Center Focus and Individual Focus. The CF system is relatively more popular among hunters and is available in more than 70% of the binoculars due to its simplistic design and easier use. However, the IF binoculars are best suited for viewing in dim lighting conditions since the focus needs to be adjusted only once. While both types of binocular focus systems are popular, people tend to prefer the Center Focus systems more. For hunting applications, slow central focusing is best used.
To maximize sales volume, sport optics manufacturers have competed in developing multi-purpose binoculars that may be used by birdwatchers and hunters equally. While it is a challenging task, several popular brands like Leica, Swarovski, and Zeiss offer general-purpose binoculars that are suitable for use in a multitude of outdoor activities instead of being limited to one.
is an experienced author from the field of sports optics. He writes articles and reviews about binoculars, spotting scopes, rifle scopes, long range shooting and other topics for magazines like Lovec and Optics-Info.com blog. Currently, he is a member of Optics Trade team.