"For years zoom eyepieces were regarded as ""convenient,"" but without the optical resolution required in demanding astronomical applications. The Meade Series 4000 Zoom Eyepiece has changed that impression completely and forever. Because, finally, this is a zoom eyepiece designed for the advanced amateur astronomer who is uncompromising in his or her optical performance specifications. Performance is fully consistent with the finest fixed focal length eyepieces. The Meade Series 4000 Zoom is an excellent addition to telescopes of all types, brands, and price levels, whether 60mm refractor, 8"" Dobsonian, 90mm ETX, or 12"" LX200 Schmidt Cassegrain. Conceived by one of the world's leading designers of photo optical instruments, this 7 element system provides an apparent field of 40� at the 24mm setting, increasing continuously to a 55� field at 8mm. The internal zoom optics move on smooth, precisely machined surfaces which maintain optical collimation at all zoom settings. A scale graduated in 1mm units indicates the zoom focal length in operation. All lenses are multi coated for maximum light transmission and image contrast, while minimizing internal reflections. The chromed brass barrel is threaded for filters. Dimesions and Weight: 1.7 x 4.2"", 0.54 lb Eye Relief: Minimum 12mm at all focal lengths."