Regardless of your vessel type or size, having access to a clear, magnified view of your surroundings is one key to safe boating. The best way to achieve this magnified view is with a good pair of marine binoculars. As you know, slapping the moniker “marine” on anything makes it more expensive, but, in this case, the “marine binocular” is a specific kind of optic—not just an expensive name change for terrestrial binoculars.
The marine environment presents challenges for binoculars and binocular viewing. Binoculars have to be built to withstand the rigors of use aboard boats (water, spray, bumps, drops, etc.). There is also the challenge of using a magnified optic on board a moving platform as any movement (of you or the vessel) will be magnified. What kind of binoculars perform best on the water? Let’s discuss your options.
The traditional size for a marine binocular is: 7×50.
Before we start to look at the 7×50 binoculars (and other options on the market), let’s first gain some knowledge about what those numbers mean in binocular speak and some other information that might inform your purchasing decision. I have broken the information into two sections: Binoculars 101 and Binoculars 102. You may skip both sections if you want to bypass some technical explanations, or you may read one or both to take a deeper dive into the world of binoculars.
Binoculars 101
Binoculars (and monoculars) are described by their magnification and size. A 7×50 binocular provides 7x magnification with 50mm objective lenses (the front lenses on the binoculars). A 10×42 binocular has 10x power and 42mm objectives.
Magnification
Many feel that more magnification is better for binoculars as you get a closer view of whatever you are looking at. While you will get a closer view, there is a serious trade-off to magnification: image stability. The more magnification, the more that any movement of the binoculars is magnified. When on the water, or with shaky hands, this can be detrimental to your viewing experience as you will be unable to hold the binoculars on a target. This shake can even be a catalyst for motion sickness.
Image stability is why 7x binoculars have been the standard for boating—they give decent magnification yet allow you to get a fairly stable view.
Size
When it comes to optics, the larger the glass, the more light can pass through the device. More light gathering usually means a brighter image (quality of the glass is also a factor here) and, with that, the ability to use the binoculars effectively in the reduced sunlight of dusk, pre-dawn hours, or poor weather.
The downside of large objective lenses? Weight. The larger the lens, the heavier it is, and heavy binoculars can be fatiguing if used for extended viewing.
Because marine binoculars don’t really need to be portable (you likely won’t take them on a hike) the large size and weight of 7×50 binoculars are fine for marine use. Just as important, the 50mm optics of standard boating binoculars give great low-light performance when you need it most.
Porro Prism vs. Roof Prism
Binoculars come in two general types—Porro prism and roof prism. The Porro prism is the binocular most of us see when we close our eyes and think of a binocular. The objective lenses are widely spaced, and the light path makes two 90 degree turns from the objective to the eyepiece. The spacing of the objective lenses gives a larger field of view and depth of field for viewers.
Roof prism configuration binoculars are popular with birding/hunting optics and have become more popular over the past decades. Ergonomically, some prefer Porro to roof and vice versa. For boaters who prefer roof prisms, there are a few 7×50 roof prism binoculars on the market.
Center Focus (CF) vs. Individual Focus (IF)
Binoculars are either equipped with a center focus (CF) dial that adjusts the focus for both eyepieces simultaneously, or individual focus (IF) adjustments on each eyepiece. 7×50 marine binoculars can be found in both CF and IF varieties.
With IF binoculars, you adjust the focus for each eye and leave it. Every time you pick up the binoculars everything past a certain distance will be in sharp focus. This can be beneficial as you don’t have to spend time adjusting focus while viewing through the optics.
CF binoculars are more traditional and, in some ways, easier to use—and share. If your binoculars are used by other crew members, it might make sense to have CF as the binoculars will not be adjusted specifically for one crew member. The adjustable focus of CF binoculars also makes them a bit more versatile for viewing nearer objects.
IF binoculars allow for quicker in-focus observations and they have less mechanicals than CF pairs, but both have advantages.
Binoculars 102
Exit Pupil
Light enters the objective lenses and exits through the ocular lenses at the rear of the binoculars. The size of the image we see is the “exit pupil.” That dimension is calculated by dividing the objective lens diameter (in mm) by the magnification. A 7×50 binocular has a 7.1mm exit pupil. An 8×42 binocular has a 5.3mm exit pupil.
Why are exit pupils important? In low light your eye’s pupil dilates. And, if your pupil is larger than the exit pupil of the binoculars (the human Mark 1, Mod 0 eyeball dilates to approximately 8mm in darkness), you will feel like you are looking through a peep hole when you peer into your binoculars. Add the movement of a vessel to that experience and binocular viewing can get frustrating when trying to look through a small opening at the rear of your binoculars.
The relatively large exit pupil of the 7×50 binocular makes that flavor of optic well suited for low-light viewing as well giving room to the movement imparted by being aboard a vessel.
BAK4 vs. BK7 Prisms
Prisms in the light path of the binocular serve to provide a “correct” image where up is up and down is down. There are two primary types of prisms in binoculars—BAK4 and BK7.
BAK4 prisms are more rounded and generally provide better light transmission than BK7 prisms. There are some good binoculars with BK7 prisms, but BK7s usually are found in less expensive pairs.
Eye Relief
Binoculars (and other optical devices) are designed to focus an image at a certain distance behind the ocular lens. For eyeglass users, this can be problematic as the eyeglasses prevent your eyes from getting to the correct viewing distance.
To accommodate this, most binoculars have diopter adjustments that allow you adjust focus for a sharp image without wearing your eyeglasses. Many binoculars also have collapsable eyecups that allow you to view with your eyeglasses on.
Field of View
You will see a degree measurement printed on many binoculars. This is the field of view (FoV) in degrees. The FoV for optics is the angular width of the projected image at 1,000 yards (or 1,000 meters). At 1,000 yards, each degree is 52.5 ft. At 1,000 meters it is 17.5 m.
Most 7×50 binoculars have a FoV around 7 degrees, but you will find that some are narrower, and some are wider. The wider the FoV, the easier it is to locate targets through your binoculars but sometimes that wider FoV comes at the expense of image sharpness around the edges.
Features of Marine Binoculars — Must-haves and Optional
Waterproof/Fog proof
In the marine environment you will definitely want a waterproof and fog proof binocular. Some models are filled with nitrogen or argon gas to keep moisture out of the insides. Avoid “weatherproof” binoculars as their protection can be insufficient for marine use.
Armor
Many binoculars—especially marine binoculars—come wrapped in a rubber armor. This helps protect the optics in the event of small impacts. Armor or not, binoculars are precision instruments that should be treated with care as impacts can knock the optics out of alignment.
Compass
Another feature of some marine binoculars is a compass that, through mirrors, projects a magnetic bearing in the eyepiece—useful for various navigation needs. Some marine binoculars now have digital compasses. Note that some of these binocular compasses may be specifically designed for the northern or southern hemisphere while others are “global.” For low-light voyaging, certain compasses are electrically illuminated by a battery.
Coatings
Optical coatings increase light transmission, reduce reflections, and increase image contrast. You will find binoculars with optics and prisms that are muti-coated, coated, or not coated. Hydrophobic coatings on the objective lenses can help keep your view clear when spray happens.
Rangefinder Reticle
Some marine binoculars have an etched rangefinder reticle that shows a vertical scale and horizon line in the eyepiece. You can use this reticle to approximate your distance from an object of known height—pretty cool!
Floating Straps/Floating Binoculars
The last place you want to send your binoculars is overboard. To help keep them from getting lost, some binoculars float on their own and others come with floating straps. You can add a floating strap to any pair of binoculars. If you have a waterproof pair, you can accidently submerge your binoculars (not too deep!), rinse them off, clean the optics, and keep using them.
Image Stabilization
Even with 7x binoculars, getting a steady image while underway is challenging. Enter image stabilization technology for binoculars. Image stabilization migrated from camera lenses to binoculars a few years back. Once an expensive rarity, advances in microelectronics are making image stabilized binoculars more prevalent and affordable.
What does this mean for the boater and their optics? Basically, image stabilization gives you the ability to use much more powerful magnifications while avoiding some image shake—giving the advantage of locating and identifying distant targets earlier than you would with less powerful binoculars. This is a great benefit for all boating applications.
It is important to remember that all of the other optical “math”—exit pupils, objective lens size, eye relief, etc.—all apply to the image stabilized binoculars. Unfortunately, there are not many image stabilized binoculars on the market with large objective lenses.
Cost
In the world of optics one might say that you “get what you pay for,” but in years of looking through dozens (hundreds?) of pairs of binoculars and writing about optics I find that the expression is not completely accurate.
In my experience, there is a huge difference in performance and quality between a $20 pair of binoculars and a $200 pair. When comparing a $200 pair to a $2,000 pair of binoculars, the differences are more difficult to spot—even negligible at times.
Because of the size and waterproof requirements of marine binoculars, you won’t find bargain basement prices, but you can find some 7×50 binoculars for under $100. I would steer clear of the lower-priced models. They will do an OK job for most tasks, but they likely won’t last as long as more expensive pairs. Many good pairs of binoculars have long (even lifetime) warranties, and they can, if treated with care, be put into your will, and your kid’s will, too!
Binoculars are a precision instrument and a tool for safety on board your vessel. If you know they will be thrashed and trashed by you or your crew, it might make sense to get a less expensive pair. If you value the bright, crisp views of a premium pair of binoculars that you plan to take care of, definitely make an investment in a quality pair. With a good, quality pair of binoculars, you’ll be more apt to use them—looking through good optics is one of life’s pleasures—and you’ll also have a binocular that will last a lifetime.
Can You Use Other Binoculars for the Boat?
Before we dive into discussion about specific marine binoculars, we can discuss using birding/hunting/general use binoculars while you are on a vessel. As lovers of the outdoors and (hopefully) lovers of premium optics, there is a chance that you have a really nice pair of 8x or 10x binoculars at home that you use for birding, hunting, or simply enjoying a scenic view.
Yes, you can use any kind of binocular onboard a sailboat—there are no regulations preventing this—but as we discussed earlier, maintaining a steady view at increased magnifications is often problematic. I might be tempted to use an 8x binocular (and I have used an 8×42 on a large ship), but an unstabilized 10x or greater binocular on a sailboat will be all but unusable unless the ocean surface resembles a mirror.
Also, birding/hunting binoculars rarely get up to the large 50mm objective size—handicapping your light gathering abilities for those low-light arrivals in a busy harbor and giving you smaller exit pupils as well.
You will find some manufacturers make smaller versions of their 7×50 marine binoculars—usually 7x30s which give you that comfortable magnification with a bit less light-gathering prowess.
The mere fact that you read Practical Sailor means you are serious about boating and that means a dedicated pair of marine binoculars is where you should spend your hard-earned money. But feel free to bring your 8x42s for birding from the anchorage or trips ashore!
Where to Buy
When buying binoculars through an authorized optics dealer like B&H Photo, Optics Planet, West Marine, or others, you are purchasing a brand new pair of binoculars that should be factory fresh and free of any issues.
However, there are some spectacular marine binoculars that are no longer in production, and they can be found both new and used on the secondary market. Retailers like B&H and others have used departments with binoculars and auction sites like eBay are full of options as well. When shopping for used binoculars, err towards the pairs that look like they were treated with care. As I mentioned before, binoculars are precision instruments and even one good drop can affect the collimation (alignment) of the pair of optics.
Some manufacturers have discontinued binoculars that are still available on overseas markets. So, if you lust after a pair that aren’t available here, use the Internet to see if you can still find a new pair somewhere.
A pro tip: Many quality binoculars have very good warranties, so you might be able to get a new-to-you used pair serviced by the manufacturer for a cleaning or even new rubber armor. Check with those manufacturers to verify before buying a used pair that you think will need service.
Select Marine Binocular Brands
Let’s take a look at several pairs of marine binoculars—many of which I have first-hand experience with. All of these binoculars are ready for the marine environment being water- and fog proof. And many of them are sold with or without built-in compasses.
One current gold standard (they do have competition) of the traditional marine 7×50 binocular is the Fujinon Polaris series of binoculars. These IF binoculars provide an exceptionally bright and wide (7.5 degree) view. They are fairly heavy and feel chunky to smaller hands. They are also renowned for their astronomical viewing performance.
Fujinon also offers a mid-range series—the Fujinon Mariner. These IF glasses are lighter and sleeker than the Polaris and still provide a nice wide view through good glass.
For those wanting image stabilization, the Fujinon 14×40 Techno-Stabi binoculars have some of the largest objective lenses of any stabilized glasses. The newest version of these features a streamlined design compared to the boxy look of the original, but specs are nearly identical. Most image stabilized binoculars are NOT waterproof, so read the specs sheet before bringing yours aboard.
Nikon’s premier 7×50 binoculars are, unfortunately, out of production. I handed a pair of Nikon 7×50 Tropicals to an optics expert at a camera store who has looked through almost every binocular known to humans—including optics that cost more than many used cars. He said, “I have never looked through a finer pair of binoculars.” You can still find Tropicals, and their astronomical brethren, the 7×50 ProStars (different coatings) online at different retailers and auction sites. They are still on the Nikon website as they are available new in some markets. I use a pair of ProStars for stargazing, but they have also been a trusty companion on merchant ships and sailboats.
The current higher-end marine binocular in production from Nikon is the 7×50 OceanPro, available with and without a compass. They are very similar in design, feel, and optical quality as the Fujinon Mariner series but, unlike the Mariners, the OceanPros are CF models.
If you are looking for an inexpensive, but solid performer, the Nikon 7×50 Action Extreme binoculars are CF models that are smaller than the OceanPros and way lighter than the Tropicals. Their size gives them great ergonomics for smaller hands and the performance for price cannot be beat.
A long-time fixture of the marine binocular market Steiner offers high end marine binoculars (with price points to match) with their 7×50 Commander Marine binoculars—another gold standard marine binocular.
The German company also offers a mid-range series, the 7×50 Navigator, with a price point that puts it in the same neighborhood as the premier offerings from Japanese brands like Nikon and Fujinon. The Navigators are also available in 7×30.
Interestingly with the brand, you can find lower priced, yet still very good 7×50 binoculars that have been given “Military-Marine” or “Tactical” designations instead of simply “Marine” in the Steiner line. These alternative Steiners are also waterproof and have slightly different specifications.
Users will find no compromises with the Steiner optics in both the Commander and Navigator line, but I find their chunky, compact design language does not feel good in my hands. Steiner 7x50s always get high ratings from users, so I have to assume that the ergonomic experience works for many—several brands even copy their looks—but I would recommend using a pair before you dive in, especially at the Steiner price point.
West Marine’s 7×50 Coastal binoculars span the range from lower price points to mid-range full-featured optics. In the past, West Marine-branded binoculars looked very much like blue versions of binoculars from other manufacturers. Today, they seem to have moved away from making loosely-disguised copies. I find West Marine optics fairly good, especially on the mid-range models. Their rubber armor has a harder, less tacky feel than some other binoculars.
Interestingly, the entire current West Marine 7×50 binocular lineup features CF models—no IF options. Of note, West Marine binocular warranties are three years—considerably shorter than some other manufacturers.
OTHERS
Bushnell makes solid entry- and mid-level binoculars. Their 7×50 marine optics are well regarded, feature a unique blue rubber armoring, have CF and IF models, and offer a limited lifetime or 20-year warranty.
German optics manufacturer Minox won a Red Dot award for their Volkswagen-designed 7×50 marine binoculars with their sleek design and multi-function digital display. They are no longer in production but look unique and the company is known for great optics.
Interestingly, Canon’s only forays into the binocular market are with image stabilized optics. They offer an image stabilized binocular with large 50mm objective lenses—the 15×50 IS binoculars. Unfortunately, these binoculars are water resistant—not waterproof. Canon does offer a 10×42 waterproof model more suitable for marine use.
Weems & Plath 7×50 binoculars bear a close resemblance to pairs from Nikon, Steiner, and Fujinon and have 2-year warranties.
For those who prefer the more compact form factor of roof prism binoculars, there are a couple of 7x50s on the market from Hawke and a discontinued model from PENTAX that can still be found new from some retailers.
Unfortunately, German optics manufacturer Zeiss has discontinued their legendary 7×50 Marine GA binocular, but they pop up occasionally online.
Recommendations
While there are hundreds of pairs of birding binoculars to choose from, the marine 7×50 binocular market (plus the few waterproof image stabilized binoculars) is a bit more manageable when it comes to making a buying decision.
If your budget allows it, you cannot go wrong with the Fujinon Polaris or Steiner Commander. I am not a fan of the Steiner’s ergonomics, so that keeps me from enjoying their amazing optics. The Polaris is a chunky, robust traditional marine binocular that feels great to my hands.
If you have the time and patience to search overseas retailers or the secondhand market, you can find some beauties like the Zeiss and Nikon Tropicals for your boat.
Mid-range choices from West Marine, Weems & Plath, Bushnell, Nikon, Fujinon, and others will serve you well if you don’t want to spend the money on premium optics.
And, if you want to save for other purchases, but get a really high-quality pair of binoculars, the Nikon Action Extreme represent possible the greatest bang for the buck in the marine binocular world.
Wish I had this thorough review when I was shopping for replacement binoculars all those years ago. As it happened, I bought Steiner Navigators as sailing buddies highly recommended them. I haven’t looked back. A very nicely written review. Thank you!
Thanks Bert!
You definitely have a nice pair of binos with the Steiners. I am glad they are working out well for you!
Thanks for reading!
Best,
Todd
I recently read an in depth argument for 7×30 binoculars. I will cut to the main point of the author: sailors of a certain age, say older than 45 years, nolongor have the same elasticity in thier iris as younger sailors. The result is that thier eyes, even after prolonged darkness, never open to 8mm. So the smaller exit pupil of a 7×30 actually projects a more complete, brighter, wider image to the retina. The larger exit pupil of the 7×50 have a significant % of image area reflecting back off the eye ball. The author went through the optical math. He reiterated that 7×50 was preferd below a certain age, and recommended carrying both if it was in the budget. And the older sailor would find the 7×30 produced better viewing for aging eyes. I have used mine next to 7×50 binos and was very happy, but I have not had the opportunity yet to compare them to 7x50s of the same quality. 7×30 Stieners against 7×50 entry level west marine may not be a fair comparison.
Hi Carl,
Thanks for chiming in! The author you reference makes very valid points and I hope to never become an “older sailor.” Ooops. Too late!
The advantages of a 7×30 pair is size, weight, and (usually) price. Having said that, my guess is that a 7×50 pair will still transmit a slightly brighter view regardless of the size of your pupil.
I don’t think you can go wrong with good pair of 7x50s, regardless of your age. But, if you want a smaller and lighter pair of binoculars (and might be an “older sailor”), then 7x30s might be a great solution.
I appreciate you sharing the information. Thank you for reading!
Best,
Todd