More Information  · Images of Some Features

The 10mm focal length of this eyepiece provides reasonable guiding magnifications with both f/10 and f/6.3 focal ratio telescopes. The eyepiece optics are multicoated for increased contrast. The eyepiece has a soft turndown batwing-type rubber eyecup to shield your eye from ambient light. The 7mm eye relief is more than twice as long as competitive Plössl guiding eyepieces. The 7mm eye relief will vignette a portion of the field for those who must wear glasses while observing. It is not a debilitating drawback, however, as the central crosshair box remains visible even with glasses and the crosshair focusing mechanism has enough range to allow most observers to remove their glasses and still focus sharply on the crosshairs.

The Astro-Tech cordless illuminator has an on/off switch with an integral brightness level control. It uses two 1.5 volt GPA76 button-type alkaline camera batteries or their equivalent (MR-44, SR-44, LR-44, 357, A76, etc.)

Please note: While the manufacturer normally supplies batteries at no cost with this product as a convenience, the battery charge or useful life is not guaranteed. The batteries may arrive with their charge depleted or very low. In such a case, you will have to purchase replacement batteries locally, as battery life is not covered by the manufacturer’s warranty.

For guiding tolerance purposes with your particular scope, you can calculate the area of sky subtended by the small central box formed by the dual crosshairs by aiming at a star near the celestial equator. Turn off the scope drive and count how many seconds it takes for the star to drift from one side of the box to the other. One second of time equals 15 arc seconds of sky.