Explore Scientific 52° Series 1.25" 25mm Waterproof Eyepiece

The 52° Series 25mm frames deep-sky targets at low magnification, with 16.4mm of eye relief. Argon-purged waterproof construction keeps it sealed for years of use.

Key Features

• Argon-purged waterproof housing, sealed and fog-proof. It is O-ring sealed and tested under 1 meter of water for 30 minutes.
• Enhanced Multi-Layer Deposition (EMD) coatings on all air-to-glass surfaces. The patented coating gives high contrast and suppresses reflections and ghosting.
• 4-element, 2-group optical design with edge-blackened elements to suppress internal reflections
• Fold-down silicone rubber eyecup with generous eye relief for comfortable viewing, including with eyeglasses. The eyecup is removable.
• 1.25" barrel. Stainless steel, tapered for a more secure hold.
• Parfocal series. All 52° Series eyepieces focus at about the same point, so swaps need little refocusing.

Ideal For

• Deep-sky observers sweeping through nebulae and galaxies at low power
• Suburban skies. This focal length darkens the background sky, and the added contrast can change how galaxies and nebulae look from the suburbs.
• Binoviewer users: the 25mm suits binoviewer devices.

Accessories & Compatibility

• 6" Tabletop Dobsonian (760 mm, f/5). In the 6" f/5 Tabletop Dobsonian, through the 1.25" adapter of its 2" focuser, the 25mm gives 30x, a 5.0 mm exit pupil and a 1.7° true field.
• 10" Dobsonian (1270 mm, f/5). In the 10" f/5 Hybrid Truss Tube Dobsonian, through the 1.25" adapter of its 2" focuser, it gives 51x, a 5.0 mm exit pupil and a 1.0° true field.
• Filters. The barrel takes standard 1.25" thread-in filters, such as the Nebula Filter CLS for light-polluted skies.