The 18mm 82° Series Waterproof Argon-Purged Eyepiece is a popular focal length in the upper-medium power magnification class providing both super-wide apparent field and generous eye relief. It is perfect for any application where more power is desired including observing globular star clusters, planetary nebulae, the bright cloud structure near the nucleus of comets, initial observations of planets, and (with the proper safe filtration on your telescope), observations of active regions of the sun. Use with Explore Scientific Focal Extenders for 2X, 3X, or 5X magnification increases while maintaining the eyepiece native apparent field and eye relief.

Using advanced computer design, combinations of low dispersion and high refractive index optical glasses, and durable enhanced multilayer deposition (EMD) coatings, Explore Scientific 82° Series super wide field eyepieces are optimized to produce high contrast, high resolution, and superior flat field characteristics. The visual effect of these eyepieces with their long eye-relief and their 82° apparent field is truly a full-immersion experience. Your eye is relaxed, allowing you to easily use the “averted vision” technique to study faint details across a huge field-of-view.

Each eyepiece is meticulously assembled into precision machined metal lens barrels that maintain the perfect alignment of the optical train for years of rugged use in the field. To keep internal reflections to a minimum, all internal surfaces of the eyepiece barrel are flat black, as well as the edges of the lenses themselves to minimize the scattering of light within the lenses themselves.

Explore Ultra-Wide Eyepieces - Comfort, Quality, Value. Explore Scientific 82° Series eyepieces, with their 82° apparent field of view, immerses you in a very comfortable ultra-wide field that naturally promotes relaxation at the eyepiece. When you relax your eyes and take in the scene presented before you, it is much easier to observe for longer periods of time, and details begin to materialize that may not have become apparent to you at first glance. Another great benefit of ultra-wide eyepieces is the 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.