Currently one of the most popular eyepiece designs in the world, the four-lens symmetrical doublet Plössl was created by Austrian optician Georg Simon Plössl in 1860.
Georg would probably be very pleased at how his original design has been improved over the past 150+ years, continually being updated with better glass types and increasingly superior coating formulations that were totally unknown to him in the 1860s. He would probably be even more pleased by how Plössl prices have become much more affordable over the years, even as the quality has gone up.
These Astro-Tech Value Line Plössls have all the optical benefits of those coating and glass type improvements, combined with the lower manufacturing cost benefits of modern computerized lens grinding. They have big performance at little prices and are a good choice when you want to get the most optical performance that a limited budget will allow.
They work well over a wide range of magnifications with any telescope type, including fast reflector "light buckets" having focal ratios as low as f/4. They have good edge-to-edge sharpness, with excellent color correction and little field curvature.
All Astro-Tech Value Line Plössls are fully multicoated for high light transmission, with blackened lens edges for high contrast. They have soft fold-down rubber eyecups for observing comfort. The longer focal lengths have rubber grip rings for easy handling in cold weather (the shorter focal lengths are physically too short to install a grip ring). All are threaded for standard 1.25” filters. Plastic caps are supplied to keep both ends of the eyepiece dust free. A groove in the chrome barrel engages your focuser thumbscrew to act as a safety stop to keep your eyepiece from accidentally falling during use.