With greatly improved optics over its predecessor, the Orion 8-24mm Pro Lanthanum Zoom eyepiece now features high-end lanthanum glass lens elements, which greatly minimize chromatic aberration. The result is clean, crisp images free of color fringing. Ideal for both astronomical and terrestrial visual applications, the 8-24mm Pro Lanthanum Zoom eyepiece can go wide or zoom in close, boasting a smooth, continuous focal length range from 8mm to 24mm. Since the focal length determines the magnification, this means you can quickly set the zoom to achieve any magnification you desire within its range ? with just a twist of the housing. For the discriminating observer, the visual rewards will be immediate and obvious, especially compared with cheaper zoom eyepieces. The Pro Lanthanum Zoom's unique parfocal design keeps your view in focus as you to change magnification so you can spend more time viewing and less time focusing, which is especially useful when tracking moving objects. Its large, rubber grip ring provides smooth magnification adjustments in any weather conditions. And speaking of which, the Orion 8-24mm Pro Lanthanum Zoom is now waterproof, so you'll have no worries about a little drizzle while you're watching that wildlife in the distance at the park. Also, the twist-up rubber eyeguard blocks ambient light and helps keep your eye in the optimal position to take in the entire view.
The 8-24mm Pro Lanthanum Zoom's optics comprise 8 lens elements in 6 groups, with 5 of the elements made from lanthanum glass. Eye relief is a comfortable 20mm through the zoom range. The apparent field of view ranges from 40° at the 24mm setting, to a wide 60° when set to 8mm. The 1.25" eyepiece barrel is tapered to prevent accidental slip-outs, and is threaded for use with 1.25" Orion eyepiece filters.