• Explore Scientific 72° ED 45mm Waterproof Eyepiece — Maximum Wide-Field Deep-Sky Eyepiece
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Explore Scientific

Explore Scientific 72° ED 40mm Waterproof Eyepiece — Maximum Wide-Field Deep-Sky Eyepiece

Explore Scientific 72° ED 40mm Waterproof Eyepiece — Maximum Wide-Field Deep-Sky Eyepiece

$449.99
$449.99
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The Explore Scientific 72° ED 40mm is the longest-focus, widest-field telescope eyepiece in the 72° ED series — a big 2" eyepiece built for the lowest-power, most expansive deep-sky views. An eyepiece sets your magnification, and this 40mm keeps power very low so faint objects stay bright, while the 2" barrel and wide 72° apparent field frame the largest nebulae, open clusters and Milky Way starfields in a single sweeping view.

Extra-low-dispersion (ED) glass keeps colours tightly focused for sharp, high-contrast views, and the eyepiece is fully waterproof and argon-purged so it won't fog internally in cold or damp conditions.

Who it's for: Observers with a 2" focuser or diagonal who want the widest, brightest low-power field for deep-sky sweeping. Not sure which focal length to pick? Read our guide to choosing the proper telescope eyepiece.

  • 2" wide-field design: the longest focal length in the series for maximum field and lowest power.
  • 72° apparent field: immersive framing of the largest deep-sky objects and star fields.
  • ED glass optics: extra-low-dispersion elements for sharp, colour-corrected detail.
  • Very low power 40mm: keeps faint nebulae and clusters bright with plenty of surrounding context.
  • Waterproof & argon-purged: sealed against fogging and moisture for all-weather use.
Specifications
Series 72° ED Waterproof
Focal length 40mm
Apparent field of view 72°
Glass Extra-low-dispersion (ED)
Sealing Waterproof, argon-purged
Barrel size 2"

What magnification will I get?
Divide your telescope's focal length by 40. For example, a 1200mm scope gives about 30x with this eyepiece.

Why choose the 40mm?
It offers the lowest power and widest true field in the series, ideal for the largest nebulae, big open clusters and sweeping Milky Way views.

Will my telescope reach its full field?
At long focal lengths the usable field depends on your scope's focal ratio; fast scopes show the widest true field with this 2" eyepiece.

Does it fit my telescope?
It requires a 2" focuser or diagonal to use its full field.

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Frequently Asked Questions

With a beginner telescope you can see a surprising amount — the craters and mountains on the Moon, the rings of Saturn, the moons of Jupiter, and star clusters like the Pleiades. As you get more comfortable, you can also spot nebulae and distant galaxies. Not sure which beginner telescope is right for you? Check out our Telescope Buying Guide.
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All telescopes on Telescope Wolves are hand-picked with beginners in mind. If you're unsure which telescope is right for you, check out our Telescope Buying Guide.
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