Two XO-series eyepieces designed for use with PENTAX-brand astronomical telescopes. Combining the outstanding benefits of the smc PENTAX O series in visual observation and the smc PENTAX XP series in astronomical photography, PENTAX developed totally new dual-purpose optics for the XO series — ideal for viewing and photographing Mars as it makes its closest approach to the Earth this August.

With focal lengths of 2.5mm and 5mm, these high-performance eyepieces are perfect for high-magnification observation and photography of the planets. Mars will be at its closest position to Earth — at the distance of approximately 55 million kilometers or 34 million miles — on August 27, 2003. Since Mars approaches and moves away from the Earth so slowly, however, that it will appear much larger and brighter than usual for at least a few months before and after August 27. This is the closest Mars will be to the Earth until the year 2287, making it a once-in-a-lifetime opportunity to observe and photograph Mars in great detail — using one of the XO-series eyepieces mounted on a PENTAX telescope.

The new XO series incorporates high-refraction, low-dispersion lanthanum glass elements to provide high-resolution images with minimal aberrations and PENTAX-original full-surface multi-layer lens coating to improve light transmission efficiency. In addition, laminated optical elements are treated with the innovative partial coating. Taking advantage of advanced computer simulation technology, PENTAX also succeeded in minimizing internal reflections to deliver a bright, high-contrast image.

The XO-series eyepieces also feature a 44-degree apparent field of view and a filter attachment diameter of 28.6mm (one and one-eighth inches). The American-standard sleeve-fitting diameter of 31.7mm (1.25 inches) allows them to be mounted on any telescope equipped with the American-standard sleeve.

Featuring a high-performance, dual-purpose optical system, the new smc PENTAX XO-series eyepieces are specially designed to give a great opportunity — for the general public as well as researchers and amateur astronomers — to observe and photograph Mars up close, and enjoy the wonder and mystery of the universe.