Marathon NSN 8x40mm BAK-4 Prism Binocular Review

First Impressions of Marathon NSN 8x40mm BAK-4 Prism Binocular

The Marathon NSN 8x40mm BAK-4 Prism Binocular is presented as a durable, military-grade optic designed for clarity and reliability. Marketed for professionals and boasting a BAK-4 prism, these binoculars aim to deliver superior light transmission in a robust package.

As an outdoor and tactical gear specialist, I’m always on the lookout for reliable optics. I specifically needed a pair of binoculars for range spotting and occasional wildlife observation while hiking, without breaking the bank.

Upon unboxing, the Marathon binoculars felt solid, with a reassuring heft that suggests durability. The rubberized armor gave me a good grip, and the focus adjustments felt smooth, though slightly stiff initially.

Compared to my older Bushnell Falcon binoculars and a compact pair of Vortex Diamondbacks, the Marathon NSN 8x40mm BAK-4 Prism Binocular offered a more substantial build and a wider field of view than the Diamondbacks, while feeling less refined than either, but more robust than the Bushnell. I chose these over similarly priced Celestron models based on the Marathon’s advertised military-grade durability and the promise of superior light transmission through its BAK-4 prism.

My first impression was cautiously optimistic. The binoculars felt rugged, but the optical clarity would be the real test.

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Real-World Testing: Putting Marathon NSN 8x40mm BAK-4 Prism Binocular to the Test

First Use Experience

I primarily tested the Marathon NSN 8x40mm BAK-4 Prism Binocular at my local shooting range and on a weekend hiking trip in the Appalachian Mountains. At the range, I used them for spotting bullet holes in targets at 100 and 200 yards.

The binoculars performed adequately in dry conditions, allowing me to identify impacts with some clarity. However, on the hiking trip, a light drizzle revealed a weakness; the image became noticeably dimmer and somewhat foggy, though not enough to completely obscure the view.

The center focus was easy to adjust, but the independent right ocular adjustment required some initial fiddling to dial in perfect focus. After a few adjustments, the focus remained sharp, with no surprises.

Extended Use & Reliability

After several weeks of use, the Marathon NSN 8x40mm BAK-4 Prism Binocular has held up well. The rubberized armor shows no signs of cracking or peeling, despite being tossed in my range bag and exposed to various weather conditions.

The exterior cleans easily with a damp cloth, and the lenses wipe clean with a microfiber cloth, but they do tend to fog up a bit in humid conditions. Compared to my higher-end Leupold spotting scope, the Marathon binoculars are significantly less clear and suffer from more chromatic aberration, but they are also a fraction of the price and far more portable.

For the price, the binoculars perform adequately. However, I would not rely on them in harsh weather conditions or for critical observation where image clarity is paramount.

Breaking Down the Features of Marathon NSN 8x40mm BAK-4 Prism Binocular

Specifications

The Marathon NSN 8x40mm BAK-4 Prism Binocular boasts the following key specifications:

• Magnification: 8x. This is a standard magnification, providing a good balance between image size and field of view, suitable for various applications.
• Objective Lens Diameter: 40mm. A larger objective lens gathers more light, resulting in brighter images, especially in low-light conditions.
• Prism Material: BAK-4. BAK-4 glass is known for its superior light transmission and image clarity compared to cheaper prism materials like BK-7.
• Eye Relief: 0.7 inches (17.8 mm). This is sufficient for most users, but those with thick eyeglasses might find it a bit tight.
• Exit Pupil: 7.1 mm. A larger exit pupil makes the binoculars easier to use, as it allows more room for eye movement without vignetting (darkening around the edges of the image).
• Field of View: 435 ft at 1000 yds. A wide field of view is crucial for tracking moving objects or scanning large areas.
• Optical Coating: Fully Broadband Multi-Coated. Multi-coating reduces glare and increases light transmission, leading to brighter and sharper images.
• Binoculars Focus System: Center Focus. A center focus knob allows for quick and easy focusing for both eyes simultaneously.
• Weight: 2.3 lb. This is a fairly heavy pair of binoculars, which could be tiring during extended use.
• Color: Black. A practical and discreet color for tactical and outdoor applications.

These specifications suggest a decent balance of performance and practicality. The BAK-4 prism and multi-coated lenses are particularly noteworthy, promising good image quality for the price.

Performance & Functionality

The Marathon NSN 8x40mm BAK-4 Prism Binocular performs adequately for its intended purpose. It provides a clear, magnified view of distant objects, making it suitable for range spotting, wildlife observation, and general surveillance.

Its strengths lie in its ease of use and relatively wide field of view. However, it struggles in low light and suffers from some chromatic aberration (color fringing), which detracts from the overall image quality.

It meets expectations for binoculars in its price range, but it doesn’t exceed them. While usable, the viewing experience is not exceptional.

Design & Ergonomics

The binoculars are solidly built with a rubberized armor that provides a comfortable and secure grip. The weight, however, can be a drawback during prolonged use.

The center focus knob is easy to reach and operate, but the independent right ocular adjustment is less intuitive. The eyecups are foldable, but not adjustable, which may be uncomfortable for some users.

Durability & Maintenance

The Marathon NSN 8x40mm BAK-4 Prism Binocular appears to be durable, thanks to its robust construction and rubberized armor. However, the lenses are not scratch-resistant, so care must be taken to avoid damaging them.

Maintenance is simple, requiring only occasional cleaning with a lens cloth. The binoculars are not waterproof, so they should be protected from rain and moisture.

Accessories and Customization Options

The Marathon NSN 8x40mm BAK-4 Prism Binocular comes with a basic neck strap and a carrying case. There are no readily apparent customization options.

While aftermarket straps can be easily attached, there are no provisions for mounting additional accessories like rangefinders or lights. This is a basic, no-frills optic.

Pros and Cons of Marathon NSN 8x40mm BAK-4 Prism Binocular

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Who Should Buy Marathon NSN 8x40mm BAK-4 Prism Binocular?

The Marathon NSN 8x40mm BAK-4 Prism Binocular is perfect for casual users who need a reliable pair of binoculars for occasional use. These binoculars would suit hikers, range users, or casual sports spectators looking for an affordable and durable option.

Those requiring high-end optical performance, waterproof construction, or lightweight design should skip this product. Professionals needing top-tier clarity and weather resistance will need to invest in a higher-end model.

A decent lens cleaning kit is a must-have accessory to maintain the image quality of the Marathon NSN 8x40mm BAK-4 Prism Binocular.

Conclusion on Marathon NSN 8x40mm BAK-4 Prism Binocular

The Marathon NSN 8x40mm BAK-4 Prism Binocular offers a reasonable value proposition for its price. It delivers decent optical performance and rugged durability in a straightforward package.

At around $50, the price is justified for casual use. The binoculars are reliable, functional, and are suitable for situations where extreme performance isn’t a necessity.

I would recommend it to anyone seeking an affordable and rugged pair of binoculars for general use. It’s a great starter set.