The basic mechanism of bincoculars consists of four parts - object lenses, ocular lenses (eyepieces), prisms and focusing system. Object Lenses are the larger lenses at the front taking light into binoculars. The bigger they are, the moe light the binoculars gather, and usually the finer the image's resolution is. It is therefore necessary to use binoculars with large object lenses in low light conditions. Ocular Lenses or eyepieces are the smaller lenses at rear delivering the final images to user's eyes. The bigger they are, the less eyestrain is put upon the user. Prisms are pieces of triangular glass inside binocular barrels correcting the image, which would otherwise be inverted and reserved without them. Focusing System lets the user adjust focal length of binoculars so that images appear sharply in eyes.

Focusing system acts as the co-ordinator between the user and the binoculars. Apart from fix-focus models, all other Bushmaster binoculars have a Central Focusing mechansim. The focusing wheel at the centre of binoculars can be turned to focus on the targeted object.

It is quite possible an average person has different eyesight between the two eyes. A right eye Diopter Adjusting System is provided to overcom the problem. Bushmaster uses two types of diopter adjust systems Right eyepiece Diopter Adjusting in which th user turns the right eyepiece ring. Central Diopter Locking (such as UCF items) in which the user presses and releases the diopter button behind the focusing wheel to twist adjust and pushes down the button to lock the setting. With your dioptric setting adjusted and locked, your vision requirements are stored without you having to adjust each tine you use the same binoculars.

Understanding the importance of immediately catching moving objects with binoculars in some circumstances, Bushmaster has developed a number of Fix-Focus models (compact, full size, water-proof) with pre-fixed focusing. If youa re going to watch races for fast-moving spectator sports, or going sailing, these binoculars are perfect to use provided a recommended minimum distance of 50 meters exists between you and the object wanted.

All Bushmaster products employ Multi-Coated Optics helping to increase the amount of useful light coming into the binoculars, thus providing an image that is brighter, sharper and clearer. Generally speaking the more layers optics are coated the better the image quality is. Having every single surface of lenses and prisms coated with light-enhancing chemicals, Bushmaster binoculars promise a light tranmission efficiency of up to 95%.

In addition, most Bushamster optics are treated with a layer of Ruby Coating on top of the normal coatings. It protects user's eye from UV emission and further increases the light transmission. It offers brilliant, crisp daylight viewing and is especially suited for use over water, snow an in other bright conditions.

Field of view is the width in meters or feet of the area you see 1000 meters (1094 yards) away. You may see the expression in degrees too, thus the term being Angle of View. One degree equals about 17.5 meters (57.4 feet) of width at 1000 meters.

High power binoculars usually have a narrower view angle compared to lower power binoculars. More efforts are needed to keep the image stable if you hold the binocular with hand. Let Bushmaster binocular holder do the job for you.

Binoculars with wider than normal view angles can give user a more comprehensive visual perception. Bushmaster has many Wide Angle binoculars. They are particularly needed for sporting events and camping. In wide angle binoculars, the prism are specially ground to have their refraction angles widened.

Bushmaster Zoom Binoculars are designed to have an extent of magnifications. For example, Bushmaster 8-20X40ZR binocular have a low of 8 magnification and a high of 20. By moving the zooming lever at the outside of the right barrel, anyu magnification within the extent can be gained. This feature presents you with a scope of viewing effects.

Fogged lenses and wet prisms are no fun to binocular users. Bushmaster Water Proof series is the solution to them. Equipped with thoroughly concealed bodies and nitrogen filled barrels, these binoculars are totallly waterproof. Fog formed inside the lenses as the result of sudden temperature change will dissipate sizes within one minute. With many models in different sizes to select, they are highly praised by people like fishing lovers, camping fans and snow skiers.

For people wearing glasses or likely to suffer from eyestrain, Bushmaster Long Eye Relief Binoculars can be very benefical. Achieved by using bigger than normal eyepieces (PLR series), this feature allows the user to place the binoculars at a longer distance from eye without affecting field of view, thus relieving the efforts of eye muscles to focus on the image. Image stability of these Bushmaster binoculars si also improved enabling the user to look for longer time.

To accomplish proper focus setting, first pull the lever to maximum power position and pick an object at far distance. Then rotate the central focusing wheel to set focus for left barrel. Next, adjust the right eye diopter until the image is focused for both eyes. Focus setting is now completed. View angle narrowws as the magnification increases. The bigger the view angle, the easier to find the position of an object. Therefore it is recommend that you set the power at lowest level and locate the object before zooming it in for detailed viewing.

Bushmaster PROFESSIONAL series (PLR) Binoculars are armed with the best available BaK 4 Prisms. These prisms are made from high density optical glass which eliminates internal light scattering, bringing you the image of highest possible fidelity. Hold the binocular about 30cm away and look through the eyepieces, you will see a perfect round if the prisms are BaK 4. In the case of BK7, the image is square with grayish edges.

Exit Pupil refers to the diameter (mm) of the beam of light coming out of the eyepieces.

The larger the exit pupil the brighter the image. In dark conditions it should correspond with the dilation of human eye pupil which usually between 2mm and 7mm. Therefore, binoculars with large object lens such as 7 X 50 (exit pupil 50/7 = 7.1 mm) will be advantageous for birding at dawn or dusk.

The alignment of the optical elements of a pair of binoculars to the mechanical axis is called Collimation. It is one of the most important aspects to inspect when you buy. Binoculars with good collimation should not form dauble image. Bushmaster binoculars are carefully adjusted and tested for their collimation by specially trained quality controllers. We strongly recommend that you choose binoculars with metal prism holders since any smallest deformation or dislocation of holders will pervert your binoculars' collimation. Holders made from soft material such plastic can be out of shaped in as little as few weeks, creating collimation defect and causing eyestrain and headache.

Bushmaster binoculars are itemized with two numbers followed by a string of letters. The first number represents the Magnifications Power. The second number indicates the diameter of the object lenses measured in millimeters. For example 8X21BR means they are 8 power binoculars bringing the object 8 times closer to naked eye. The size of the object lenses is 21mm. The letters at the end are associated with the model design of the product. Backed by the strength in expertise and technology of its manufacturing base, Bushmaster produces a wide range of models, giving you the flexibility in choosing binoculars to serve your needs.