The eyepiece threads into place. To prevent accidental loss in the field, a rubber O-ring at the base of the eyepiece threads compresses as the eyepiece is screwed into the scope body. This locks the eyepiece in place to keep it from vibrating loose during transport and use. The O-ring also seals the scope against the entrance of dust and moisture. A roll-down rubber eyecup is standard. Rolling it up shields the eye from extraneous light for higher contrast non-eyeglass use. Rolling it down lets you get closer to the eyepiece for less-vignetted eyeglass use. Slip-on plastic dust covers are provided for both ends of the eyepiece.

With a 50mm Fieldscope the eyepiece provides 40x magnification, with a 1.25mm exit pupil, and a good field of view of 94’ at 1000 yards.

With a 60mm Fieldscope the eyepiece provides 60x magnification, with a 1mm exit pupil, and a good field of view for the magnification of 63’ at 1000 yards.

With an 82mm Fieldscope the magnification increases to 75x and the exit pupil to 1.09mm, while the field of view decreases to a still generous 52’ at 1000 yards. The performance is the same with older 78mm Fieldscopes as it is with the newer 82mm versions, except that the exit pupil is a somewhat smaller 1.04mm.

The eye relief is specified at 17mm with all scopes, for virtually unvignetted eyeglass views. While this is technically correct, the actual usable eye relief will typically measure somewhat less due to the recessing of the eyepiece lens to protect it from being scratched accidentally when the eyecup is in the down position for eyeglass use. A somewhat shorter eye relief than specified is typical of all spotting scope eyepieces.