Explore Scientific 72° ED Series 6.5mm Waterproof Eyepiece (1.25")

High-power planet and Moon views with 18mm of eye relief

The Explore Scientific 72° ED Series 6.5mm Waterproof Eyepiece is the high-power member of the series, for planets, the Moon and close double stars. It has a 72° apparent field, a 1.25" barrel, 18mm of eye relief and an 8mm field stop, and its optics include H-FK61 ED glass to keep color fringing low and contrast high. Explore Scientific builds the series to be waterproof, and this eyepiece weighs 275g (9.7oz).

Key specs: 6.5mm focal length · 72° apparent field · 1.25" barrel · 18mm eye relief · 8mm field stop · 7 elements in 5 groups · H-FK61 ED glass · waterproof · 275g (9.7oz)

What you'll see

• Planets: Jupiter's cloud belts and the Great Red Spot, Saturn's rings and the Cassini Division, and the polar caps of Mars near opposition.
• The Moon: crater walls, rilles and mountain shadows along the terminator.
• Small, bright targets: the Ring Nebula (M57), the cores of globular clusters, and close double stars such as Epsilon Lyrae.

In an 8" Dobsonian (1200mm) the 6.5mm gives 185x and a 0.38° true field. In an 80mm f/6 refractor (480mm) it gives 74x and a 0.95° field. For comparison, the full Moon is about 0.5° across.

Why the 72° ED series

• Wide without the bulk: 72° is wide enough to frame objects with plenty of sky around them, while keeping the eyepiece smaller and lighter than 82° and 100° designs.
• ED glass: an H-FK61 fluorophosphate element (Abbe number 81.6) reduces color fringing on bright stars, the Moon and planets. Coatings are multi-layer.
• 18mm eye relief: comfortable for most eyeglass wearers.
• Waterproof: dew and damp nights are less of a worry, and the eyepiece is easier to keep clean.

What to add for the best results

• A good diagonal: for refractors and Schmidt-Cassegrains, the Celestron 1.25" Dielectric Star Diagonal has a twist-lock that holds the eyepiece securely.
• A Barlow: the Celestron 2x Omni Barlow doubles the magnification, turning this eyepiece into an effective 3.25mm.
• More of the series: pair it with the 8.5mm for a matched set with the same 72° field and feel.

Which 72° ED eyepiece is right for you?

See all our eyepieces.

What's in the box

• Explore Scientific 72° ED 6.5mm eyepiece with dust caps

Diagonals, Barlows and filters are sold separately.

Explore Scientific 72° ED 6.5mm FAQ

Will it fit my telescope?

It has a 1.25" barrel, which fits nearly every telescope, including those with 2" focusers when you use the 1.25" adapter they come with.

What magnification will I get?

Divide your telescope's focal length by 6.5. In an 8" f/6 Dobsonian (1200mm) that's 185x; in an 80mm f/6 refractor (480mm) it's 74x; in a Celestron 8" SCT (2032mm) it's 313x.

Can I use it with glasses?

Yes. 18mm of eye relief is enough for most people who observe with glasses.

6.5mm or 8.5mm?

The 6.5mm is the highest power in the series (185x in an 8" Dob), best when the air is steady. The 8.5mm (141x) is easier to use on average nights.

Is it really waterproof?

Explore Scientific sells the 72° ED series as waterproof eyepieces, which helps on dewy nights and when cleaning. Dry it before putting the caps back on.

Specifications