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The Oberwerk Mariner 8×40’s standout feature is its wide 8.4° field of view, a useful advantage for scanning the sky or following wildlife. The tradeoffs are substantial weight, a relatively wide minimum interpupillary distance, and a model that Oberwerk says was discontinued roughly a decade before its 2020 update. This is a review of its documented specifications and a 2014 reviewer’s experience—not a new hands-on test.
What the Oberwerk Mariner 8×40 is
The Mariner is an 8×40 binocular built around a broad view and rugged construction. Oberwerk’s Mariner Series flyer described the range as waterproof and nitrogen-filled, with rubber armor, a metal body, and shockproof prism mountings. It listed nautical use as well as birding, hunting, surveillance, and astronomy. These are manufacturer descriptions and archived specifications, not independently verified performance claims. Oberwerk’s Mariner Series flyer
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The 8×40 model has fully broadband multi-coated air-to-glass surfaces, oversize BAK4 prisms, a rigid center focuser, right-eye diopter adjustment, twist-up eyecups, and a brass 1/4-20 tripod adapter socket. Oberwerk listed a padded rip-stop nylon case and 1.5-inch denim strap in the package.
Specifications at a glance
| Specification | Oberwerk Mariner 8×40 |
|---|---|
| Magnification and objective diameter | 8×, 40 mm |
| Field of view | 8.4° |
| Exit pupil | 5.0 mm |
| Eye relief | 18 mm |
| Interpupillary distance (IPD) | 60–73 mm |
| Minimum focus | 5 m |
| Dimensions | 5 in long × 7 in wide × 2.5 in high |
| Weight | 2.2 lb in Oberwerk’s flyer; Space.com reported 37 oz in its 2014 review |
The 5 mm exit pupil is the 40 mm objective divided by 8× magnification. Oberwerk’s flyer lists the same figure. The weight figures come from different sources and are not identical, so they are best kept attributed rather than treated as one reconciled measurement. Space.com’s 2014 review
#1 Best Overall
- LONG-RANGE CLARITY: Premium Sport ED Binocular delivers powerful 8x magnification and a wide 8.1° FOV, making it perfect for advanced-level bird watching and wildlife viewing, or any application where flawless color rendition is necessary, rendering crisp, true-color images on long outings.
- SUPERIOR ROOF PRISM VISION: Oberwerk's signature broadband multi-coatings, dielectric and phase-coated prisms, ensure the highest-possible image quality. The internal focusers can focus as close as 6 feet away, giving precise subject lock and rapid adjustments in the field.
- ENHANCED USER COMFORT: Ergonomic design reduces fatigue during extended use while twist-up eyecups provide comfortable eye placement for users with or without glasses. Textured rubber armor improves grip and handling on long hikes and active excursions in varied terrain.
- WEATHERPROOF RELIABILITY: Whether bird watching, hiking, sailing, or exploring, you don't have to worry about the weather. The Sport ED binoculars are fully waterproof and sealed against moisture and dust, ensuring dependable performance in damp or challenging outdoor conditions.
- LIGHTWEIGHT MAGNESIUM-ALLOY CONSTRUCTION: Our Sport ED models are lightweight, yet durable, with dark green rubber armor over a magnesium-alloy body, with attractive red-anodized aluminum components. Twist-up eyecups help maintain optimum eye position for extended observation.
How it performed in the 2014 review
Space.com reviewer Dave Brody described the Mariner as a broad-view binocular for astronomy and outdoor use. He reported sharp star points and crisp lunar detail, and praised the wide field for scanning. He also found it substantial in hand and noted that its bridge could pinch his nose because of his close-set eyes. Those observations belong to one reviewer; they are not a guarantee of fit or a current test by this publication.
Space.com recorded a field of 437 feet at 1,000 yards and called the Mariner an Editors’ Choice for Best Small Binoculars for Astronomy. Oberwerk’s 2020 post likewise identified the recognition as a Space.com award from 2014. It is a historical award, not a current ranking. The review’s reported $150 street price is also historical and should not be used as a present-day price.
Rank #2
- TOP QUALITY AND BUDGET-FRIENDLY BINOCULARS: A great pair of binoculars that combines top engineering features with an economical price. Perfect for backyard birdwatching, sports events, nature and wildlife viewing, hunting, travel, boating, concerts, and live events.
- EVERYTHING YOU NEED IS INCLUDED: Start your adventures today with this durable pair of water-resistant full-size binoculars. Accessories include: carrying case, objective covers, eyepiece covers, lens cloth, and instruction manual.
- TOP AMERICAN OPTICS ENGINEERING: These 8x40 powerful binoculars provide you with multi-coated BK-7 prism glass that increases light transmission, resulting in brighter and sharper images with high contrast levels and 8x magnification to get you even closer to the action.
- A DURABLE AND COMFORTABLE BODY: The Celestron UpClose G2 8x40 water-resistant binocular will be your event, birding, or hunting buddy for many years to come. The stylish waterproof exterior features a rubber-covered aluminum body, ergonomic thumb indents, and finger ridges for extra non-slip comfort and ease of use.
- UNBEATABLE WARRANTY AND CUSTOMER SUPPORT: Buy with confidence from Celestron, a leading optics brand based in California since 1960. When you purchase from an Authorized Dealer on Amazon, you will receive a Celestron Limited Lifetime US Warranty and unlimited access to technical support from our team of US-based experts.
Fit, handling, and eyeglass comfort
Check the minimum IPD before buying
The listed IPD range is 60–73 mm. Oberwerk acknowledged in a 2017 customer response that the 60 mm minimum could be too wide for some users. If your eyes are closer together than the binocular’s minimum setting, you may not be able to merge the two images comfortably. If possible, try the binocular or confirm your IPD against its range before buying.
Expect a substantial binocular
At 2.2 lb in Oberwerk’s flyer, the Mariner is a heavy choice for a 40 mm binocular. That may matter during long handheld sessions, especially when scanning overhead. A standard 1/4-20 socket allows optional tripod mounting; a tripod is not required by the specifications or review, but may help if the weight becomes tiring.
Eye relief is a specification, not a fit guarantee
Oberwerk lists 18 mm of eye relief and twist-up eyecups. That figure can help eyeglass wearers assess whether the binocular may work for them, but actual usable view depends on the eyeglasses, face shape, and eyecup position. The available evidence does not establish a universal eyeglass-fit result.
How it compares with Oberwerk’s named alternatives
Oberwerk said in 2020 that the Mariner Series had been discontinued roughly ten years earlier and named the 8×42 Deluxe as the 8×40’s replacement. The table compares archived manufacturer figures: Mariner values come from its series flyer, while the two 8×42 models’ figures come from Oberwerk’s 2023 chart. Check the current specifications if considering either alternative, since later revisions are not established here.
Rank #4
- Powerful 8-16x zooming capability allows quick and easy changes in magnification to suit the viewing situation with excellent target resolution across the entire magnification range.
- High-performance optics provide a bright, clear field of view with superb transmittance and sharp, high-resolution images with minimal distortion and chromatic aberration even in low light conditions.
- Built with a durable, high-quality finish the robust housing resists any nature conditions - ideal for outdoor use. A rubber coated grip ensures a safe hold for easy and comfortable operation.
- Maximum comfort, functionality and portability are guaranteed due to a compact, lightweight size and ergonomic controls. The focus wheel is responsive and easy to operate even if wearing gloves.
- A rubber eyepiece and lens cover plus soft carrying case offer a solid protection. While the strap ensures a high level of wearing comfort and allows quick access to be ready for the next scene.
| Model | Field of view | Weight | IPD range | Eye relief | Minimum focus | Waterproof / nitrogen-filled | Intended-use information |
|---|---|---|---|---|---|---|---|
| Mariner 8×40 | 8.4° | 2.2 lb (Oberwerk flyer); Space.com reported 37 oz in 2014 | 60–73 mm | 18 mm | 5 m | Yes, according to Oberwerk’s Mariner flyer | Flyer lists nautical use, birding, hunting, surveillance, and astronomy |
| 8×42 Deluxe | 8.0° | 2.3 lb | 56–74 mm | 13 mm | 10 m | Not stated in the cited 2023 chart | Not stated in the cited 2023 chart; Oberwerk named it as the Mariner 8×40’s replacement |
| 8×42 Sport ED | 8.1° | 1.5 lb | 58–75 mm | 15 mm | 2 m | Not stated in the cited 2023 chart | Not stated in the cited 2023 chart |
The Mariner has the widest listed field in this comparison. The Sport ED is lighter and focuses closer; the Deluxe has a slightly wider IPD range at the narrow end than the Mariner, but its listed eye relief is shorter. The cited chart does not establish the alternatives’ waterproofing or nitrogen filling, so those features should not be inferred from their names or category.
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Oberwerk’s 2020 account says the Mariner Series had been discontinued roughly ten years earlier. That makes the 8×40 a discontinued model, not a product whose current new-stock availability or price can be assumed. A listing that appears today should be checked individually for new or used condition, completeness, seller, and whether its description matches the Mariner 8×40. The historical Amazon link on Space.com does not establish current stock.
Best Value
- 8x magnification & 42mm objective lenses, these Crossfire HD binos are optimized with select glass elements to deliver exceptional resolution, cut chromatic aberration and provide outstanding color fidelity, edge-to-edge sharpness and light transmission.
- Fully multi-coated lenses increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces. Roof prism design is valued for greater durability and a more compact size.
- Fully multi-coated lenses increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces. Roof prism design is valued for greater durability and a more compact size.
- Rubber armor provides a secure, non-slip grip, and durable external protection. Binoculars are tripod adaptable allowing use on a tripod or car window mount.
- Nitrogen purging and o-ring seals provide water and fogproof performance in all environments. Rugged construction withstands recoil and impact.
If you want the manufacturer-named successor, compare the 8×42 Deluxe as a separate model rather than treating it as the same binocular. Oberwerk’s replacement statement and archived chart support that comparison, but do not verify current revisions, availability, or seller terms. Oberwerk’s 2020 discontinuation and replacement notice Oberwerk’s 2023 binocular chart
Verdict
The Mariner 8×40’s documented appeal is straightforward: a very wide field, rugged manufacturer-described construction, and a historical reviewer’s positive account of astronomical views. Its weight and 60 mm minimum IPD are meaningful fit and handling constraints, and its discontinued status makes condition and listing accuracy central to any purchase. It is most compelling to someone who specifically values the wide view and can verify that the binocular fits and is in acceptable condition.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
