Having a reliable pair of binoculars on board your boat is essential. They are a very important navigational tool that will help keep you in the channel and out of harms way. Figuring out which pair of marine binoculars to buy is a challenge, they are expensive and there are so many styles, features and price points. Buying binoculars for your boat is a relatively expensive purchase that you expect to get years of use from. So making the right choice is important. This buyers guide for marine binoculars helps you understand what to look for in a marine binocular and to help you determine which binoculars are right for you based upon features, quality and price.
Here are 9 important considerations in determining which marine binocular to buy and 9 top binoculars at different price points:
1) Magnification: The first question in buying binoculars for use on your boat is what is the best magnification? A 7×50 binocular is well suited for use on a boat because it offers a great combination of magnification, brightness in low light and accommodates a use with movement caused by waves and weather. The 7 in the 7×50, refers to the magnification. This means that the image is magnified 7x which is the practical magnification limit for small boat. Magnification greater than this are great for land based usage like bird watching or hunting but provide too much magnification for marine usage because pitching and rocking.
The 7×50 is the most common magnification for marine use but you will also see 8×30 for use on larger boats or 7×30 binoculars. Increased magnification reduces the brightness of the image, so as magnification increases, binoculars require increasingly larger objective lenses to maintain brightness. The larger their size, the more light they can gather and the brighter the image in low light situations.
2) Waterproof binoculars: It is obvious that binoculars for your boat need to be waterproof. It is not just to protect them from elements like spray and rain. But the damp marine environment, combined with changes in temperature, causes interior lenses of non-waterproof binoculars to fog. Waterproof construction, with the interior o-ring sealed and filled or “charged” with dry nitrogen protects your binoculars from condensation damage or even if they if they fall overboard.
3) Lens coatings: Lens coatings help to reduce reflected light which will reduce brightness and crispness of the image. Binocular lenses are coated using one or more thin layers of chemicals, typically magnesium fluoride, which reduce internal reflection from 5% (with uncoated glass) to 1% or less. Given that the light passes through numerous lenses and not just one, minimizing reflection is important.
Lens coatings vary in quality, If you look at the outside lens surfaces, quality lens coatings will appear as subtle tints of violet, blue or green. Heavily colored lenses in cheap glasses enable less light to be transmitted. Higher quality binoculars will include more layers, on more surfaces, to achieve their much better light transmission efficiency. Here are some of the alternatives you will find:
* Coated: one or more surfaces coated with a single layer. * Fully coated: all air-to-glass surfaces are single-layer coated. * Multi-coated: one or more surfaces coated with multiple layers. * Fully multi-coated: all air-to-glass surfaces are coated with multiple layers
4) Durability: Things on boats tend to get bumped around more than they do on shore. Binoculars are no exception. Less expensive boat binoculars tend to be lighter weight and more expensive binoculars a little on the heavier side. While light weight binoculars have their advantages on board from a comfort perspective, they might not stand up to the rigors of the marine environment as well as beefier binoculars.
5) Light Transmission: An important factor in binoculars for marine use is image brightness, especially in situations where you depend upon your binoculars most like during evenings, morning at night or in rain or fog. Less expensive binoculars will typically allow less light light entering the objective lenses to reach your eyes. Less expensive marine binoculars may allow only pass about 75% of the light. Higher end binoculars will allow ~90% of the light to pass and exceptional binoculars, such as top models from Steiner and Fujinon, pass between 93% to 97% of light to your eyes. The result is these binoculars make all objects appear brighter and are better for low light situations. Quality optics also make the image sharper. Inexpensive glasses may produce astigmatic images that are fuzzy at the edges. Superior glasses are sharp from edge to edge and are less fatiguing to the eyes when used for extended periods.
6) Prisms: Prisms come in two basic glass types, BK-7 and BAK-4. BK-7 uses boro-silicate glass and BAK-4 use a denser, finer barium crown glass, which more effectively prevents internal light from scattering and produces sharper images than BK-7. Binoculars made with BAK-4 glass tend to be more expensive but the quality of brightness does make a difference.
7) Focus: Marine binoculars may either have independent eyepiece focus or a center focus. The independent eyepiece focus compensates for the differences between eyes and for different distances. If your eyes focus differently, this is an important consideration. In center focus binoculars, one eyepiece adjusts to accommodate the difference between your eyes. A central focus knob on the top of the binocular then adjusts both sides for distance. The convenience and easy one handed use (so you can use the other hand to hold on!) is important and we tend to like the central focus binoculars for use on a boat.
8) Bearing compass: Some marine compasses come with built in bearing compasses. Some of the more expensive marine binoculars have bearing compasses that are accurate to ~1% while others are far more subject to the motion of the boat and are only accurate to ~5%. This feature helps to take bearings on distant objects to plot your position or to help other people find the object when you pass them the binoculars. Binoculars with a bearing compass are recommended for marine use.
9) Range finder: Binoculars with a rangefinder will help to calculate the angle from the base to the top of the object, if you know it’s height. This enables you to accurately calculate your distance from that object.
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We are all about passing along knowledge of the best marine products so you can more fun on your boat and on the water. Because that’s what it’s all about!
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