The Pentax XW40-R 40mm Wide-Angle Eyepiece is engineered to deliver a relatively low magnification, with a wide field of view and a long eye relief—making it ideal for taking in wide swaths of the night sky for deep-space visual exploration. Its long eye relief makes it extremely comfortable during long observation sessions while offering you the ability to utilize the averted vision techniques that allow you to see faint details of elusive objects like wispy nebulae and galaxies. Viewing comfort is also optimized for eyeglass wearers. This eyepiece in the XW line is offered with a large 2" nosepiece to fit larger drawtubes, visual backs, and accessories for maximum light transmission and comfort.
This eyepiece is built with extra-low-dispersion lanthanum glass in a 6-element/5-group lens configuration with anti-reflection multi-coatings and phase coatings. The combination of glass, lens design, and optical coatings virtually eliminates chromatic and spherical aberrations and maximizes light transmission to ensure bright and crisp, high-contrast images with true color transmission across the entire visible spectrum without ghosting or halos. To keep internal reflections to a minimum and improve contrast, the inside of the barrel has a light-shielding diaphragm. A twist-up rubber eyecup prevents stray light from leaking into the eye, further boosting contrast.