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How to Pick Binocular Power
By: Buster Carnelli
The most important step in selecting a pair of binoculars is to figure out the power you need. Binocular power is indicated by two numbers, as in these examples: 6x30, 7x35, 8x42, 10x42, and 12x60. The two numbers are not directly related; the first indicates the magnification and the second number expresses the diameter of the objective lens.
-- Magnification --
The first number, invariably the smaller of the two, expresses the amount of magnification that the binoculars allow for. This is an indication of how much nearer the observed image will look when viewed with the binoculars. While bigger sounds superior, this is not always the case with binoculars. Choosing the optimal magnification will depend on your intended use.
Lower magnification binoculars, those with magnification of 7x or less, provide for a bigger field of view which can make targeting objects far away—like animals, ships, or birds—easier. A bigger field of view also makes it easier to follow movement of the object being watched. Since lower magnification binoculars show more of the scene, lower magnification binoculars bring in more light. Because of this, the resulting image will be brighter and easier to see even though it is not as greatly magnified. Because of the lower magnification, they are also less sensitive to vibration or movement. If you are going to be in the wild using your binoculars without the use of a tripod, this can be a critical consideration. Finally, lower magnification binoculars often are able to focus on objects that are nearer than equivalent higher magnification binoculars.
But when it's all said and done, lower magnification binoculars allow for less magnification, and therefore reduced detail when compared to higher magnification models. If you genuinely want high magnification binoculars, 11x and higher, for your use, be certain you additionally get a tripod or get a model with an image stabilization feature. The greater the magnification, the more affected binoculars are to movement and vibration. Once you starting talking about 10x magnification binoculars, they will be nearly impossible to use without an image stabilization system or a tripod. Larger magnification binoculars also tend to be heavy. So if you intend to use them for an extended period of time, a tripod will be a better option than a model with image stabilization.
As for expense, it shouldn't be too surprising that higher magnification models tend to be more expensive than equivalent lower magnification binoculars. Unless you have special needs or uses intended for your binoculars, a reasonable middle-of-the-road magnification amount is 8x. Binoculars with this magnification level offer a nice trade-off of magnification while providing low weight, good brightness, and reasonable cost.
-- Objective Lens Size --
The second number in the power corresponds to the diameter of the objective lens in millimeters (mm). The objective lens is the lens in the front of the binoculars, furthest from your eye. Smaller objective lens tend to indicate binoculars that are smaller in overall size.
Binoculars with objective lens sizes of 30 mm and under are usually found on pocket and compact models. While compact and pocket binoculars are lighter and easier to carry, the downside to reduced lens size is that the smaller lenses let in less light. This can make images darker and more difficult to see. If you plan on using your binoculars at nighttime, models with smaller objective lenses will not be a good choice.
If brightness, or nighttime use, is important, objective lenses that are 50 mm or larger will work best for you. However, binoculars with large objective lenses will most often be heavy and large. If you plan to use binoculars of this size, you should definitely have a tripod available, independent of the magnification level.
The most common objective lens sizes used are between 35 and 50 mm. Since the magnification level also has an effect on the brightness of the image (higher magnification is darker), the objective lens sizes tend to increase as magnification increases to balance out the lost brightness. For a good general rule, consider binoculars that have an objective lens diameter that is at least 5 times larger than the magnification. For example, 7x35, 9x45, 12x60, etc. While there are some binocular manufacturers with extraordinary optics that will provide excellent brightness at a ratio well under 5, the safest thing is to stay at or above this ratio for good brightness.
Article Source: http://www.ezarticles.info
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