Explore Scientific Extreme Wide Field 82 Series 6.7mm Waterproof Eyepiece 1.25 inch Barrel Review (2026)

Who this eyepiece is for

The 82 Series 6.7mm is a high power eyepiece meant for observers who already own a mid to longer focal length wide field eyepiece and want to push into planetary, lunar and tight double star territory without losing the wide, immersive field that makes premium wide angle eyepieces enjoyable to use. At 6.7mm, the exact magnification it delivers depends on the telescope's focal length, so it works best paired with the calculation for your specific scope rather than as a general purpose eyepiece. Because a 82 degree apparent field feels like a window rather than a tunnel, it suits people who find narrower eyepieces claustrophobic at high power and are willing to pay a premium for that experience.

Optical design and waterproofing

Explore Scientific builds this eyepiece with a seven element, four group optical design using combinations of low dispersion and high refractive index glass, aimed at controlling the edge distortion and chromatic aberration that can creep into extreme wide field designs. The lenses carry full multicoating to improve light transmission and contrast, and the barrel is O-ring sealed and argon purged so the eyepiece is fully waterproof rather than simply water resistant. Purging with argon rather than plain dry nitrogen keeps the internal air moisture and dust free over the eyepiece's life, which also means there is no risk of trapping cleaning fluid between internal lens elements the way there can be with unsealed designs.

Eye relief and handling at the telescope

This eyepiece is specified with around 14mm of eye relief, which is workable for eyeglass wearers at this focal length though tighter than the long eye relief eyepieces built specifically for glasses wearers. The 1.25 inch barrel fits any standard focuser or diagonal without an adapter, and the eyepiece is noticeably heavier than a basic Plossl or Kellner because of its element count, so lightweight refractors or diagonals with loose set screws may need attention to keep the eyepiece from slipping. A twist up or fold down eyecup, typical of this eyepiece class, helps position the eye consistently at the correct distance during long observing sessions.

What to expect through the eyepiece

Because 6.7mm is a short focal length, the eyepiece is more demanding of both the telescope's optical quality and the night's atmospheric steadiness than a longer eyepiece in the same series, and on nights of poor seeing the extra magnification can show more atmospheric shimmer rather than more detail. On steady nights it rewards the observer with a genuinely wide, sharp field for tracking a planet drifting across the view without needing a motorized mount to keep it centered, since the 82 degree field takes noticeably longer to drift out of frame than a 50 degree eyepiece at the same power. Star testing at the edge of the field shows the multi-element design controlling field curvature well for a wide angle design.

Verdict and how it compares

This eyepiece earns a strong score for observers building out a matched set of Explore Scientific 82 Series glass, delivering the brand's signature wide, comfortable field at a demanding short focal length. Within the wide angle eyepiece comparison it belongs to, it ranks near the top of the group, just behind the longer 14mm version in the same series and ahead of several 68 degree alternatives from other brands, reflecting the tradeoff buyers make between field width and price. Anyone assembling a full set of high, medium and low power eyepieces for serious planetary and lunar work will find this a logical high power choice, while first time buyers on a budget may want to start with a longer focal length in the range.

Frequently asked questions