Featuring a versatile zoom range and generous field of view for easy and comfortable glassing, the Pentax XF smc 6.5-19.5mm Zoom Eyepiece is designed for use with their 100, 80, and 65mm spotting scopes or any telescope or spotting scope that accepts standard 1.25" eyepieces. The wide zoom capability produces a high power at one end and a low power at the other, allowing you to view a wide range of subjects without the hassle of having to change eyepieces or carry a lot of gear. Extra-low dispersion lanthanum glass in the 6-element/4-group lens design provides a balanced image with minimal aberrations, while the proprietary smc anti-reflection multi-layer lens coatings prevent reflection for optimal light transmission. The eyepiece is constructed to be water resistant, easily withstanding light rain or dew. For digiscoping, there is a 43mm mounting thread under the removable twist-up click-stop eyecup for attaching your rings and adapters.