The original post on this site was a sales description of the Polaris Optics Raven 8×25, now sold under the Wingspan Optics name. This rewrite keeps the listed specifications, removes claims we cannot check, and explains what this ultra-compact binocular is best for.
Verified specifications
Specifications as listed in the product description:
- Magnification: 8x; objective diameter: 25 mm
- Field of view: 432 ft at 1,000 yards
- Minimum focusing distance: 5 m
- Eye relief: 9.34 mm
- Weight: 12 oz
- Waterproof and fogproof
Corrections to the original listing
- Marketing phrases such as “HD quality” and “one of the most lightweight, compact revolutions ever designed” were removed as unverifiable.
- The listing gives no prism type or exit pupil; the exit pupil below is calculated from the 8×25 figures.
What the numbers mean
Every binocular carries two numbers. Astronomy magazine’s binocular guide explains that the first is the magnification and the second is the diameter of each front lens in millimetres, so a 8×25 magnifies 8 times and has 25 mm lenses.
- Exit pupil: aperture divided by magnification. 25 ÷ 8 gives about 3.1 mm, fine in daylight but small for night viewing.
- Why exit pupil matters at night: the same guide says most people under 30 have dark-adapted pupils of about 7 mm, around 6 mm in their 30s, and probably no more than 5 mm from age 40. A bigger exit pupil than your eye can use simply wastes light.
- Field of view: to convert feet at 1,000 yards into degrees, divide by 52.5. 432 ft works out to about 8.2°, a genuinely wide view that makes birds easy to find. Astronomy magazine says most binoculars cover about 6° to 7°, high-power models 3° to 5°, and wide-angle models 8° to 10°.
- Eye relief: Nikon’s guide says eye relief of 15 mm or longer lets most eyeglass wearers see the whole field without removing their glasses. At 9.34 mm, it is not well suited to eyeglass wearers.
Is it good for stargazing?
Astronomy magazine recommends at least 40 mm lenses for astronomy and says 35 mm or smaller binoculars won’t gather enough light for good views of most night-sky objects. At 25 mm, the Raven is a daytime binocular. It can still show the Moon and help you spot the Pleiades, but for star clusters and galaxies a 10×50 or similar is a better choice.
Setting up your binoculars
Bushnell’s Trophy owner’s guide describes the standard set-up that works for most centre-focus binoculars:
- Eyecups: twist them up if you do not wear glasses, so your eyes sit at the right eye relief distance and you see the full field of view.
- Interpupillary distance: point the binoculars at a blank wall or sky and move the two halves closer or farther apart until you see a single circle with no shaded areas.
- Focus the left side: cover the right objective lens, then turn the centre focus knob until a detailed distant object looks sharp through the left side.
- Set the diopter: cover the left lens instead and turn the diopter ring under the right eyepiece, not the centre knob, until the right side is sharp.
- Remember your setting: note the diopter mark so you can reset it if someone else uses your binoculars.
What you can see in the night sky
According to Astronomy magazine, binoculars show the Moon in crisp detail, including shadows moving across lunar features as it waxes and wanes and earthshine on a crescent Moon. They also let you follow the phases of Venus and the motions of Jupiter’s big moons. Beyond the solar system, large star clusters such as the Pleiades in Taurus and the Beehive in Cancer fit nicely in a binocular view, and the Andromeda Galaxy (M31) stands out from a dark site. The magazine says more than 400 deep-sky objects lie within reach of good binoculars from a dark-sky site.
Care and cleaning
The Trophy guide’s cleaning advice applies to any binocular: blow or brush away dust first, then wipe in a circular motion with a microfibre cloth. For a thorough clean, use photographic lens tissue and lens-cleaning fluid, always applied to the cloth and never directly on the lens. Never use household window cleaner or paper towels, which can damage coatings or scratch the glass. Store the binoculars in a cool, dry place.
Safety
Never look at the Sun through binoculars or any optical instrument. Bushnell’s guide warns this may permanently damage your eyes.
Quick summary
- 8×25 ultra-compact, 12 oz.
- Wide 432 ft (about 8.2°) field; about 3.1 mm exit pupil.
- 9.34 mm eye relief; close focus 5 m.
- Made for birding on the go; limited for stargazing.
Jargon buster
- Objective lens: the big front lens that collects light.
- Exit pupil: the small bright circle of light you see in each eyepiece when you hold the binoculars away from your eyes.
- Diopter: an adjustment for differences between your two eyes.
- Roof vs Porro prism: roof models have straight barrels; Porro models have the classic zigzag shape.