Often considered the perfect mid-range focal length for most amateur telescopes, the 20mm 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.
Specifications
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
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