Binoculars are telescopic devices that are purchased for sight watching. While purchasing binoculars, not many are too serious about the qualities. It’s mainly because this device is used for short period, usually during vacations or tours to beautiful scenic locations.
But there are also adventure lovers, who are very serious and specific while purchasing binoculars. Specially bird and wildlife watchers, nature fanatics, sports analyzers etc. need these binoculars for minutely watching vivid movements accurately. Such people know what they need in their binoculars.
Here is an extensive guide for common people, what to look for while purchasing binoculars.
Large Binocular Magnification
This is the very first thing you should look for while purchasing binoculars. For common use, anything between 5x and 15x will be sufficient. The larger the magnification, the more effective is the device. A magnification of 10x will mean that an object at actual distance 1000 metres will appear to be at 100 metres with the device.
Note that to avoid shaking you will need tripod stand for using magnifications above 12x.
Large Objective Lens Aperture
Always look, if the lens facing objects is of large aperture. Large lenses are very crucial for better pictures. Large objective lenses allow greater amount of light to enter inside the device and hence deliver better picture quality. Large objective lenses allow better images even in low light conditions.
Good binoculars have their objective lens diameter 5 times or more (in mm) of the overall binocular magnification. This means, if magnification is 10x then the objective lens diameter should be greater than 50 mm. Such specifications are denoted by 10×50 (in this particular case).
Field of View (FOV) and Exit Pupil
FOV (Field of View or Field of Vision) is a measure of the apparent area of vision together. Larger FOV means you will be able to see more area together, without moving the binocular. An Apparent FOV of angle greater than 60° is considered good enough.
Exit Pupil refers to the size of the image formed on the eye-piece lens available for the pupil to see. Exit Pupil Diameter (in mm) is calculated by the ratio of Objective Lens Diameter (in mm) and Binocular Magnification. Exit Pupil Diameter of 7 mm is considered the most ideal and is also effective for use in low light situations such as dusk or cloudy day.
Good Lens Quality and Coating
Ensure that the objective lenses has good coating. Good coating prevents light from reflecting back and provides more light to enter inside the device for clear images.
Also, the lens quality is important to ensure better color, better contrast and aberration free vision. If you wear glasses, then you should go for large eye-piece lenses (lenses facing the viewer).
Strong, WP (Waterproof) and UV Ray Protection
Binoculars are essentially used in outdoors. So it will be good if the device is strong enough to handle unintentional drops.
Also, make sure the device has at least some degree of waterproofing. Now, Ultra-Violet Ray protected binoculars are also available which ensure that you can use the device for longer periods even in strong sun light.
Size and Weight of Binocular and Eye Strain
Make sure that the device is not too heavy and bulky to tire your hands while using and uncomfortable in carrying.
Also ensure that the device is not causing strain to your eyes on prolonged uses.
Night Vision Binocular with IR (Infra Red)
Night Vision IR Binoculars can be useful for night explorers. But IR Technology considerably increases the cost of the device. So, its on your purpose, if you need this feature or not.