The 5mm focal length is where most high-power observing actually happens. At 240x in an 8-inch Dobsonian, you've hit the crossover point — magnification high enough to show real planetary detail and resolve close double stars, low enough that average seeing isn't shutting you down. The XWA 5mm does something unusual at this focal length: it offers a 110° apparent field. Wider than any standard high-power eyepiece, wider even than some "wide-field" designs at longer focal lengths. Nine elements in six groups, fully multicoated, with edge-blackened elements that control stray light at magnification. The result is an eyepiece that works on a wider range of nights than any narrow-field competitor, delivering contrast and sharpness where most observers spend most of their eyepiece time.
The Optics
Five millimeters is the high-power sweet spot — short enough to reach useful magnification without requiring exceptional seeing, long enough that the atmosphere isn't your limiting factor on average nights. The XWA's nine-element design at this focal length is engineered around one principle: maintain sharpness and contrast across the field while keeping aberrations in check across a broad range of focal ratios. Whether you're in a fast f/4.7 Dobsonian or a slow f/10 Schmidt-Cassegrain, this eyepiece maintains good correction across a range of focal ratios.
Edge-blackened elements absorb the internal reflections that wash out contrast at magnification, especially on low-contrast targets like planetary detail and faint nebulae. FMC coatings further reduce reflections. At high magnification on Jupiter's Great Red Spot or Saturn's Cassini Division, that matters.
The Practical Eyepiece
This is the eyepiece for the observer who wants real magnification without real constraints. On an 8-inch scope, 240x is serious power. On a 10-inch Dobsonian, it's 300x — genuinely high power but still manageable on moderate seeing nights. On an SCT, it's approaching 400x, which demands good seeing but isn't unreasonable. The 110° field means you see context. You're not hunting across a tiny field to assemble a picture of what you're looking at. You see the scene with much more context.
What's Included
- Sky Rover XWA 5mm Extra Wide Angle eyepiece
- Dual 1.25"/2" barrel adapters
- Foldable rubber eyecup
- Lens caps (top and bottom)
- Lens cleaning cloth
Features
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110° apparent field of view — The highest AFOV in the XWA line at 5mm focal length. Immersive high-power observing without tunnel vision. See the whole planetary disk, the entire nebula, full context.
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9 elements in 6 groups — Complex optical formula solves problems at high magnification. Each element corrects something: edge sharpness, field curvature, distortion, internal reflections.
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Edge-blackened optical elements — Eliminate stray light before it reflects internally and destroys contrast. Critical at magnifications where low-contrast detail (planetary features, nebular shape) matters most.
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FMC broadband coatings — Reduce reflections across the visible spectrum. More light to your eye means better contrast on detail.
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5mm focal length — the practical high-power sweet spot — 240x in an 8" Dob (good on many nights), 182x in a 130mm refractor (comfortable margin), ~400x in a typical 8" SCT (demands good seeing but achievable).
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Stainless steel lower barrel — Precision fit in 2" focusers. Rigidity without bulk. Resists corrosion.
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Dual 1.25"/2" interfaces — Universal compatibility. Foldable eyecup lets glasses wearers dial in the full field.
Under the Night Sky
Jupiter in moderate to good seeing is where this eyepiece earns its price. At 240x in an 8-inch scope, the Great Red Spot shows clearly — not just its outline, but its color and internal structure. The North and South Equatorial Belts resolve into distinct features. Festoons, ovals, shadow transits of Galilean moons — it can be seen in the field on steady nights. The 110° field means you're seeing the entire planetary disk without hunting to assemble a picture.
Saturn shows the Cassini Division clearly, with hints of the Crepe Ring in steady seeing. Cloud belts on the planet. The apparent thinness of the rings at different seasons becomes visually obvious at this magnification. The Cassini Division at 240x is one of those views that makes you understand why you bought a telescope.
Double stars near the resolution limit of your aperture — Epsilon Lyrae's four components, Castor's tight binary pair — can be split at this magnification under good conditions with room to see color and brightness differences between the components.
Observing Tip
The 5mm XWA is your high-power workhorse. It works on more nights than any 3.5mm eyepiece, yet delivers the magnification most observers want most often. If you own just one XWA, make it the 5mm. Pair it with a 7mm or 9mm for observing that doesn't demand high power, or with a 3.5mm if you want to push magnification on exceptional nights. The 5mm is the anchor.
FAQ
Is 240x too much magnification for an 8-inch Dobsonian?
Not on most nights. The 8-inch can handle 240x comfortably when atmospheric seeing is decent (stars twinkling but steadying out at low power). On truly exceptional nights, you'll want to push it. On average nights, drop to the 7mm or 9mm XWA for better performance. That's smart observing, not settling.
Will this work in a Schmidt-Cassegrain?
Absolutely. In an 8-inch f/10 SCT, 240x from the 5mm is well-matched. In a 10-inch SCT, you're at 300x — still reasonable. In a 12-inch SCT, you're at 360x, which demands good seeing but isn't unreasonable. The wide field helps because you can see detail across the entire planetary disk even when the magnification is high.
How does the 110° field change the high-power experience?
Dramatically. A standard 5mm eyepiece has a 50–52° apparent field. At 240x, that's a tiny window. With the XWA's 110° field, you see planetary surface detail, surrounding context, and neighboring stars all at once. No hunting. No assembling a mental picture from fragments. You see what you're looking at.
Accessories
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Sky Rover XWA 7mm or 9mm eyepiece — Lower magnification companions for average nights and extended viewing. The 7–9mm range is more forgiving of seeing conditions.
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Sky Rover XWA 3.5mm eyepiece — If you want even more magnification on exceptional nights. Ultra-high power with the same wide field.
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2" eyepiece case or padded storage box — Protects the optics and your investment.
Final Thoughts
The 5mm XWA is the high-power eyepiece for observers who want to actually see planetary detail without living in a tunnel. Most observers will spend more time with this focal length than any other in their eyepiece collection. Pair it with a 7–9mm for a two-eyepiece observing kit, and you've covered most of the high-power work you'll want to do. On a 240x night when Jupiter is high and steady, you'll put this in the focuser and remember exactly why you bought the telescope.
