With original box. Open box condition, near mint.
The 55mm focal length has the largest true field possible for 2" eyepiece holders -3 times the true field area of any 1¼" eyepiece. The focal plane is placed at the end of the barrel to minimize vignetting. Performance with Schmidt-Cassegrains is remarkable since it avoids the image degradation and severe vignetting which occurs when using telecompressors. Long eye-relief and unique adjustable eyeguard for eyeglass wearers.