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Explore Scientific 52° LER Eyepiece 20mm Argon Purged Eyepiece


Quick Overview

The Explore Scientific 52° LER Eyepiece 20mm Ar is an excellent choice for those wanting to use medium to lower powers in their shorter focal length telescopes, or medium powers in medium to long focal ratio instruments. Argon-purged, this eyepiece is waterproof to stand up to the most challenging of observing conditions.  It's LER - or Long Eye Relief - design of 15mm, means that even those who wear glasses to observe will find viewing through this range a comfortable and rewarding experience.

  • Large eye distance and great image sharpness

  • 15mm eyerelief

  • Excellent viewing position for people with glasses

  • Excellent field sharpness even with fast optics

  • 52° apparent field of view

  • Patented EMD"-coating to maximize contrast

  • Blackened lens edges to avoid reflexes

  • Argon-purging prevents internal fogging, the sealing facilitates cleaning

  • Stainless steel barrel with conical security cutoff

  • Dust covers and protective bag included

Only 202 left

Availability: In stock



Often considered the perfect mid-range focal length for most amateur telescopes, the Explore Scientific 52° LER Eyepiece 20mm Ar on the ED127 at f7.5 produces a 1 degree true field of view. Perfect for the Messier Marathon, or running down the Herschel Catalog. The 20mm 52° Series is also a good selection for most binoviewers with its relatively small size and magnification range.

Explore Scientific Waterproof Eyepieces - Comfort, Quality, Value. The Explore Scientific 52° Series™ eyepieces are excellent flat-field multi-element oculars that can transform your visual astronomy experience. With an apparent field of view of 52 degrees, these eyepieces offer incredible value in a very nice eyepiece. Expect exceptional quality and value versus a comparably priced Plossl.

Another great benefit of these eyepieces is the excellent contrast and ease with which you can gaze, not directly at an object, but slightly to either side. This skill, called using averted vision, is especially helpful when observing faint objects, because using averted vision puts the image on a part of your eye that is more sensitive to light, allowing you to see fainter images.

Description 20mm 52° Series Argon-Purged Waterproof Eyepiece
Item Number EPWP5220-01
Focal Length 20mm
Length 71mm
Width 43mm
Weight 181.4 grams; 6.4 oz. 
Barrel Size/Type 1.25” O.D. / Double Taper
Eye Relief 15mm
Field Stop Diameter: 18.2mm
Coatings: EMD (Enhanced Multi-Layer Deposition) on all lens-to-air surfaces
Lens Elements/ Groups 5 Elements in 3 Groups; Edge Blackened
Filter Thread Fits Standard 1.25-inch Dia. Thread in Filters (1.125-inches x 42 TPI)
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

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