Choosing a pair of binocular
Though you do not need to be a tech-savvy or a sales rep to buy a good pair of binoculars. You do not need to know what every part of the binocular is called to enjoy birds with it. So in this article, I am keeping it simple and limiting jargon to a minimum and giving you a basic outline of what you require to buy your first pair of binoculars for birds.
Since binoculars are the most important equipment used for birding choosing the right one is very important. –However, remember it's not a life or death decision and it will be ok if end up with not the perfect binoculars, you can always upgrade later–. While using a pair of binoculars each person will have their own preferences. It is always recommended that you use fellow birders’ binoculars to see what suits you the best. Seek advice from birder instead of the counter sales rep.
Magnification and Aperture:
You must have noticed that binoculars have numbers printed on them like 8X40 or 10X50. The first of these numbers is the binoculars’ magnification; the second is the diameter of the objective lens. The magnification indicates how much ‘closer’ the binocular will get you to your subject or in other words how much bigger the binocular will make the bird appear. People often jump to the immediate conclusion (like always) that higher magnification should be better, well as the cliché goes bigger is not always better. It's always the combination that matters most. Higher you go in terms of the magnification it reduces brightness, and field of view, and is unstable. For birding, the ideal range for magnification is between 8X to 10X.
The second number indicates the aperture in regard to the objective (front) lens size. The larger the objective the lighter it can gather and thus gives a brighter image, also it brings more of the habitat into view making it easier to track flitting birds. However the larger the objective the heavier it gets. Usually, a range of 40mm to 50mm is considered an ideal balance between low light performance and portability. In all cases, a zoom binocular is never recommended.
For birding in forest, a binocular of combination 8X40 or similar is ideal, however for wetlands especially when watching waders a 10X binocular is recommended. Though it is not feasible to own and carry two pairs of binoculars, thus a roof-prism binocular of magnification 10X42 or 10X50 gives you a good balance of zoom field of view and portability.
Field of View (FOV):
The field of view is how wide (large) an area can be seen through the binoculars. It is usually expressed as an angle (6°). A binocular with a larger field of view makes it easier to stay on a moving object and thus binoculars with a wide field are generally preferred by birdwatchers.
A common misunderstanding is that the objective lens diameter aperture in the field of view. Even binoculars with a narrow objective lens diameter can have a wide field of view; it's because it has more to do with the physical length of the binocular and the configuration and design of eyepiece lens elements.
Field of view is measured in feet at 1,000 yards see diagram below:
Depth of Field:
Depth of field for a binocular is often overlooked. Though it is a personal choice a greater depth of field binocular is preferred to enjoy the behaviour of birds, where you do not have to change focus every time the birds move closer or further away.
Coatings:
Coatings are layers of material added to the surface of the lens to improve the performance of optics, by altering the way in which the lens transmits or reflects light. They are primarily used to increase the amount of light that gets through the optics and into the eye. Coatings have benefits such as improving contrast and reducing glare. You should be aware that not all coatings are the same. To carry the title of "coated", optics only have to have a single layer of magnesium fluoride on one lens. To be "fully coated", all lenses have to be covered with at least one layer of coating. The fully multi-coated binoculars are considered top of the line and are very expensive.
Quality and Cost:
The quality and the cost of the binoculars range tremendously from some very basic models costing Rs. 1,500/-* to Rs 1.5 Lac* for the big brands like Swarovski. However, you need not spend a small fortune to have a good pair of binoculars, good quality 8X40 binoculars can cost between Rs. 7,000/-* to Rs. 9,000/-*.
* Cost as per May 2017
Diopter Adjustment:
The diopter adjustment is designed to let you compensate for differences between your own two eyes. If the diopter is not set properly, it can make the binocular unusable, since both your eyes can never focus at the same distance at the same time. Many a time the binoculars are blamed for not being good.
Setting the Diopter:
To set the diopter, first set it to zero (1), and now cover the front lens (2) of the side that has the diopter adjustment (usually the right). Look through the binoculars (3) and adjust the focus wheel until the image is as clear as possible (4). Then uncover the lens and cover the opposite one (5). Look through the binoculars and if the image is not clear, adjust the diopter until the image is clear (6) for that eye. Now you can uncover both lenses and see through the binocular and using the top wheel adjust to get a sharp image (7). |
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** Images in this blog have been obtained from multiple sources on the internet (like www.birdwatching.com, www.primalucelab.com etc) for non-commercial and educational use and may be subject to copyright
