Explore Scientific


Explore Scientific 40mm 52° 2-inch O.D. Argon-Purged Waterproof Eyepiece

Considered a mandatory focal length in your collection, the 40mm Explore Scientific 52° is a must-have for all astronomers.

The 52°-series eyepiece features a standard 2" barrel to make it compatible with the most popular size drawtubes and accessories.

  • EMD anti-reflective multi-coatings ensure bright, high-contrast images with true color transmission across the entire wide field of view.
  • Great for viewing celestial objects by using averted vision
  • The fold-down rubber eyecup prevents stray light from leaking into the eye, further boosting contrast.
  • The eyepiece is internally sealed and purged with inert, dry argon gas, which maximizes the life of its internal coatings.
  • The eyepiece is tested by submerging it down to 1 meter of water for 30 minutes.
  • Fully multi-coated and edge-blackened to produce maximum contrast.
Focal length 40mm
Length 96,6mm
Width 61.8mm
Weight 385.5g; 13.6 oz.
Barrel Size/Type 2.0" O.D. / Double Taper
Eye Relief 27.1mm
Field Stop Diameter 36.3mm
Coatings EMD (Enhanced Multi-Layer Deposition) on all lens-to-air surfaces
Lens Elements/ Groups 4 Elements in 2 Groups; Edge Blackened
Filter Thread Fits Standard 2.0-inch Dia. Thread in Filters (48mm x 0.75mm)
Waterproof O-Ring Sealed Argon Gas Purged; Tested Under 1 Meter of Water for 30 Minutes
Eyecup Removable Flip-Down Style Soft Silicone Rubber
Lens Caps Slide-on Top and Bottom
Materials Optical Glass; Aluminum; Steel; Silicone Rubber
Markings Laser Engraved: Focal Length; Series; Serial Number; Brand