Marine Binoculars

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The Marine Binocular

The water is a pretty unique environment and as such brings it's own special needs. Binoculars designed specifically for boating will thus have some pretty specific features. In this guide I will go through what to look out for, to help you find the best marine binocular for your needs.

Waterproof Binoculars

Obviously a waterproof binocular is the single most important feature of a marine binocular. But try and look for binoculars that are completely O-ring sealed as well as nitrogen-purged. This will ensure that your boating binoculars will remain waterproof and fog proof in any season or weather conditions. (importance 10/10)

Marine Binocular Magnification

Out on the open water you are mostly going to be looking at objects much further away than you would on land and as such, you would think that the bigger magnification, the better. The problem with this is the larger the magnification, the less stable the image you are looking at through them becomes, combine this with the fact that the platform of you boat will not be stable means that very high power binoculars become difficult to use on the water.

Most of the best marine binoculars tend to have a 7x magnification, this still gives you plenty of power and will mean that your image is not too unstable to view.

Image Stabilization Binoculars (IS)
If you really want more magnification than 7x the best advice would be to go for a set of binoculars that have built in Image Stabilization. (For more take a look at my guide to Canon Stabilized Binoculars)

For an excellent example on how Image Stabilization can help steady the image on a boat take a look of the video below created by Yachting Monthly, using the ujinon Techno Stabi 14x40 stabilised binoculars.

So to sum up magnification for marine binoculars, I would stick to 7x or if you wish to go higher use Image Stabilized Binoculars. (importance 7/10)

Rangefinder Binoculars

The Rangefinder on marine binoculars is different to the laser rangefinder found on many binoculars designed for hunting. This is because the distances are usually to far for the laser rangefinder binoculars.

Marine binoculars use a grid rangefinder, where you use the known size (or best estimate) of an object you are viewing (height or width) to calculate it's distance from you. (importance 4/10)

Compass Binoculars

Many binoculars built for marine use come with an integrated compass that will enable you to pinpoint the bearing of a object. This is not important, but is a nice feature to have. On many models, the compass is illuminated for use at night which will require batteries. (importance 3/10)

Objective Lens Size

This is the size of the large lens at the end of your binoculars, it is indicated in the name of the binoculars and is measured in millimeters. so for example the Steiner 7x30 Marine Binoculars have an objective lens diameter of 30mm. The larger the objective lens, the more light your binoculars let in, this is important for low light conditions. Obviously the larger the lenses, the larger the binoculars, so most compact binoculars that you are going to carry about in the field tend to have smaller objective lenses. Generally marine binoculars are stored on a boat and as such size is not as critical, the most popular marine binoculars tend to have 30mm or 50mm objective lenses. (importance 5/10)

Type of Focus

You find good marine binoculars with either individual eyepiece focus (fixed focus) or center focus.

Fixed Focus Binoculars
Once you have set the binoculars to your eyesight they do not need to be focused again, these are sometimes confusingly known as self focusing or auto focus binoculars. This system works well when looking at objects from medium to far distances away and the advantage of not having to focus using your binoculars on a moving boat is obvious. They also often used on marine binoculars because they have far less moving parts than center focus binoculars making them much easier to seal and make completely waterproof.

Center focus Binoculars
These need to be focused using a central barrel, they are far more versatile than fixed focus binoculars, which is important if you plan to use a binoculars for viewing objects at closer ranges.
(importance 4/10)

Field of view

The field of view on marine binoculars is not as important as it is for people using their binoculars to view unpredictable, fast moving objects, like birds. Field of view is basically the width of the scene that is in view when you look through your binoculars, for a full explanation see field of view in my optics glossary. A wide field of view will make it easier to find objects when looking through the binoculars. The down side is loss of pinpoint detail that you find in high magnification binoculars. In simple terms lower magnification often means wider field of view. A field of view that is too wide will often result in distortion at the edges of the image. So what you are looking for is the wider field of view as possible in your chosen magnification. (importance 2/10)

Size & Weight of Marine Binoculars

Apart from personal preference, the size and weight of marine binoculars is not as important as it would be for binoculars used for wildlife viewing or birdwatching as they are designed to be carried around in the field. Marine binoculars are generally stored onboard and only used when needed. If you plan to use your binoculars for more than just boating binoculars, this may become an important factor. (importance 2/10)

Balance of Binoculars
Related to the size and weight of binoculars, the balance of a set of binoculars is quite important especially if you plan to use them for extended periods. Unfortunately it is not something you can compare without trying out the binoculars yourself, having said that if you are going for a quality pair of binoculars, they will all be pretty well balanced and you will probably not go wrong here. Well balanced binoculars should put very little stress on your arms, wrists, and hands when you hold them up to your face. A badly balanced pair, will strain your muscles making viewing for long periods a task as well as making harder to keep steady. (importance 5/10)

Eye Relief

Eye relief on a set of binoculars is very important if you use glasses. Take a look at Eye Relief in my glossary for a detailed explanation, but basically it is the distance behind the ocular lenses where the image is in focus. So if you wear glasses, you can't get your eyes as close to the lenses, you need a longer eye relief that basically projects the image beyond the ocular lens on the binoculars. So if you wear glasses, you should be looking for an eye relief of at least 15mm, to see the full image full image. The down side to long eye relief is that it usually reduces the field of view. Some people wonder if you need to wear glasses at all using binoculars, well If you are near-sighted or far-sighted, you can use your binoculars without wearing glasses and the binoculars focus will compensate, but if you have astigmatism, you will need to use your glasses.

Eye-cups are related to the eye relief as they keep the distance from the oculars to our eyes, but also help keep stray light away from your eyes while using binoculars. Many eye-cups are made from rubber and can roll up or down depending on whether you use lasses or not. The problem with these is that the constant rolling causes the eye-cups to break. Another type are eye-cups that slide rather than roll, but these can be hard to keep in place. The third type are eye-cups that twist up and down and so they can be left at any position from all the way up to all the way down, some even have click stops at regular intervals with the eye relief distance for each stop marked on the cup so you can get the perfect eye relief for your vision. (importance 8/10 if you uses glasses not hugely important if you don't)

Below are some binoculars that I recommend as great boating binoculars.

View >> All Marine Binoculars