Explore Scientific 72° ED Series 40mm Waterproof Eyepiece

The Explore Scientific 72° ED Series 40mm Waterproof Eyepiece is an H-FK61 extra-low dispersion glass eyepiece with a 72° apparent field of view, waterproof argon-purged construction, and long eye relief.

The H-FK61 ED glass sharply reduces chromatic aberration compared to standard eyepiece designs, producing cleaner star points and higher contrast across the field. The 72° apparent field of view is wide enough to create a panoramic, immersive viewing experience. Argon purging prevents internal fogging in humid conditions, and the waterproof housing means dew-soaked nights won't damage the optics.

Key Features

• H-FK61 extra-low dispersion glass — reduced chromatic aberration for sharper, higher-contrast views
• 72° apparent field of view — immersive wide-field viewing without tunnel vision
• Waterproof and argon-purged — sealed against moisture, fog-proof in all conditions
• Long eye relief — comfortable extended viewing for both eyeglass wearers and unaided observers
• 2" barrel — the wider format allows a larger field stop
• Multi-layer coatings on all air-to-glass surfaces for maximum light transmission

Ideal For

Maximum field, minimum magnification — designed for the widest field of view in the series. An excellent choice for observers who want a wide field, long eye relief, and the optical clarity that ED glass provides. Compatible with any telescope accepting 2" eyepieces.