Explore Scientific 100° Series 9mm Waterproof Eyepiece Argon-Purged

Explore Ultra-Wide Eyepieces - Comfort, Quality, Value. The Explore Scientific 100° Series™ eyepieces are hyper-wide class oculars that can transform your visual astronomy experience. You may be startled at the amazingly wide expanse of inky black sky you behold the first time you bring your eye to a 100° Series eyepiece, and after awhile, you may even forget that you have an eyepiece between you and the universe! With an apparent field of view that is close to the maximum for hyper-wide eyepiece design, objects are not only easier to locate, but for non-driven telescopes the object will stay in the field of view for a very long time before any adjustments need to be made. Another great benefit of hyper-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. Specifications Focal Length: 9mm Barrel Diameter: 2" Length: 145mm Width: 60mm AFOV: 100 degrees Eye Relief: 12.5mm Field Stop Diameter: 15.7mm Coatings: All lens-to-air surfaces are fully multi-coated Eyecups: Soft rubber folding style; Replaceable Weight: 21.2 oz.