Tele Vue 21mm Ethos 2" Eyepiece

While exploring the celestial wonders, the 21mm Ethos 2" Eyepiece offers an unparalleled "spacewalk" experience. This eyepiece is designed to transform your astronomical journey through the Milky Way, providing a unique blend of contrast, power, and field. It excels in showcasing larger deep sky objects and rich star fields, making it a must-have tool for every stargazer.The 21mm Ethos eyepiece offers a stunning 100-degree field-of-vision, filled with stars. Regardless of where you focus, you'll experience sharpness and richer contrast, enhancing your overall viewing experience. This superior optical performance is the result of meticulous design by Ethos lead designer, Paul Dellechiaie. He has achieved an impressive level of optical aberration correction, consistent with his other Ethos designs.The eyepiece utilizes advanced coating techniques to maximize contrast and transmission. The internal mechanical design techniques, synonymous with all Tele Vue eyepieces, further enhance these features. The 21mm Ethos eyepiece pushes the boundaries of the 2" barrel and focus constraints, providing the maximum true field of view without significant vignetting at the field's edge. It is parfocal with the 31mm Nagler Type 5, offering seamless transitions between views.The 21mm focal length completes the logical set of 21mm/13mm/8mm and complements the 17mm/10mm/6mm combination. Each step within these two sets approaches a 3x field area gain. The 21mm Ethos eyepiece has an effective field stop diameter of 36.2mm, bringing its true field close to the 35mm Panoptic (38.7mm Field Stop diameter). It also offers a larger true field than the 26mm Nagler with its 35mm effective field stop diameter.In an f/4 Dobsonian, the exit pupil is just 5.25mm using the 21mm Ethos, compared to 8.75mm with a 35mm Panoptic, or 6.5mm with a 26mm Nagler. Like all Tele Vue eyepieces, each 21mm Ethos undergoes rigorous optical and cosmetic quality control procedures in Chester, NY. Should your eyepiece ever require service, we can handle everything from replacing a dented barrel to a scratched eyelens.All Ethos models accept Dioptrx, allowing you to compensate for your eyesight astigmatism with a high-quality multi-coated lens providing your exact correction, rotation orientation, and centration over the eyepiece. This is the culmination of our commitment to delivering observing experiences "even better than you imagined," and a 30-year recognition of being "tops in the field."