Review: Maven B4 Series 10×56 Binocular


All images by Alan Dyer.

Lens coatings are superb, with the glass almost disappearing. An additional coating protects against scratches and fingerprints. The binocular is nitrogen filled and claimed to be waterproof even if submersed for 30 minutes.

Available only direct from

$1,045 USD (Used demo unit)

$1,100 USD (New stock unit)

$1,450 USD (Custom-built unit)

Plus: Top-class optics, solid construction, American built.

Minus: High weight, eyecups can pinch, case not included.

Made in the U.S., the Maven 10×56 binocular provides optical performance to rival the best from Swarovski and Zeiss, at a fraction of the price.

Who Is It For?

Binocular fans wanting the best optics, and willing to spend $1,000 to get them.

If you’d like the pleasure of owning one of the finest binoculars for astronomy, I have an interesting option for you to consider. It’s a roof prism model from a binocular company you likely haven’t heard of, yet they are American.

Premium Prisms

While we’d like to think of binocular companies as catering to us astronomers, the truth is that instead, hunters drive the development of premium “low-light” binoculars. Top-class 50mm and 56mm binoculars, built for stalking game in twilight, are also ideal for astronomy. With rare exceptions such as the Nighthunter series from Steiner in Germany, which use classic Porro prisms, most high-end binoculars use roof prisms to fold the light path.

In the premium price league, the prestigious Austrian company Swarovski offers their SLC models, the up-and-coming U.S. company Vortex has their Razor UHD line, while legendary Zeiss in Germany has their Conquest and Victory HT series.

All these top-class binoculars employ “Abbe-Koenig” roof prisms, named for the Zeiss opticians who invented the design patented by Zeiss in 1905. Abbe-Koenig prisms are physically longer, heavier and more difficult to manufacture than the lower-cost Schmidt-Pechan design used in all other roof prism binoculars. However, Abbe-Koenig prisms have a higher light transmission, by 5 to 10 percent. Due to their cost, their use is reserved for only the very best low-light binoculars. But if those glasses carry a name like Swarovski or Zeiss, even Vortex, expect to pay $2,000 to $3,000.

Eye relief is a comfortable 16mm, with the eyecups clicking up and down through four positions, to accommodate eyeglass wearers. The eyecups are large, so much so that for anyone with closely set eyes they will pinch the nose when twisted up all the way for non-eyeglass use.

Boutique Binoculars

There is a lower-cost alternative, and it’s American. In surveying the binocular market I discovered Maven, a small company based in Lander, Wyoming. They cater mostly to hunters, selling their premium optics only factory-direct, reducing markups. Their B2, B4 and B5 series of binoculars all use Abbe-Koenig prisms, ED or fluorite glass, 4-element “apo” objective lenses, and have wide 65° to 67° apparent fields of view, among the widest you’ll find in any binocular. Their optics come from Japan but are assembled in San Diego, California. The binoculars tick all the boxes for quality, but sell for a half to a third of the competition, though still in the $1,000 league.

I tested their B4 10×56, for me an ideal magnification and aperture for binocular astronomy. At 51 ounces (1440 grams), the 56mm Maven is certainly hefty, surprising considering its polycarbonate body. But I found that the mass does dampen out fine jittery vibrations when hand-holding the binoculars. The dual- or open-bridge design aids in holding the binoculars firmly.

In side-by-side tests with low ($200) and mid-priced ($500) 50mm and 56mm binoculars, the Mavens presented images that snapped into sharper focus, with no false color on the limb of the Moon, a flaw present even in some ED-glass binoculars. The Moon looked bright white, not pale yellow as it did in lesser binoculars. Stars seen only with averted vision with a conventional roof prism 10×56 were obvious with direct vision in the Mavens. Faint nebulas such as the Veil and North American were a touch brighter; dark nebulas stood out with a bit more contrast against Milky Way starfields.

In keeping with the Maven’s optical excellence, stars appear as pinpoints across 80 percent of the wide 6.7° actual field. Even at the very edge, star images remain small and relatively free of off-axis aberrations. By comparison, a good mid-range binocular fares well if its central 60 to 70 percent is sharp, with stars often severely bloated toward the edge. The field is fairly flat, exhibiting just a small amount of barrel distortion as the binoculars are panned across the sky.

While hand-holdable, the sharpness of the Mavens is best appreciated by mounting them on a tripod. While the 1/4-20 socket accepts any tripod adapter, Maven offers the Outdoorsmans adapter, shown here. It uses a stud that remains on the binocular, for quickly clamping on the adapter, making it easy to move the binocular on and off a tripod.

The focusing mechanism is smooth and precise, even in winter, which is not the case with the greasy mechanisms of some binoculars that freeze up in the cold. Maven’s warranty is lifetime and unconditional; even if you carelessly break your binoculars, Maven will repair or replace them.

If you are in the market for a top-end binocular, I recommend checking Maven. As they sell only direct, to test a Maven you have to order a lightly-used demo unit. The unit is sent with the option to return it within two weeks, either for a full refund (less shipping) or to credit its cost toward a custom-built unit. Or you can do as I did — just keep the discounted demo model. It’s become my favorite astronomy binocular.

The Maven comes with lens caps, neck strap, and a soft, microfiber bag. The hard shell case is a $30 option. Not supplying elaborate boxes and packaging also keeps Maven’s and your costs down.

About Alan Dyer

Alan Dyer is an astrophotographer and astronomy author based in Alberta, Canada. His website at has galleries of his images, plus links to his product review blog posts, video tutorials, and ebooks on astrophotography.

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