The smc PENTAX XW23 eyepiece delivers an apparent field of view of 85° -- the widest viewing angle in the XW series, suitable for observing nebulae and star clusters. It features a new optical system with 7 elements in 5 groups, delivering sharp star images all the way to the edge of the field of view. It incorporates multi-layer coating for outstanding light transmission efficiency, advanced light-shielding technology for improved image contrast and weather-resistant construction. (Note: while the eyepiece features a weather-resistant structure of JIS class 4, it cannot be used underwater.)