A twist of the zoom eyepiece housing changes focal length from 21 mm to 7 mm providing a variety of viewing magnification powers; excellent contrast and sharpness making the zoom also of interest for planetary observing
Exceptionally long 16 mm to 33 mm eye relief range allows eyeglass wearers to enjoy the entire view while still wearing their corrective lenses without vignetting; the Zoom eyepiece lets you change magnification power without physically changing eyepieces
Apparent field of view is 30 degree at 21 mm and 43 degree at 7 mm; rubber traction ring ensures a good grip; the 1.25 inch barrel is threaded for filters; actual magnification range will depend on the focal length of your telescope
85mm focal length and reduction factor of about 0.5x that depend on spacing; 0.5x focal reducer effectively halves the focal length of a telescope for enabling lower magnification;
Mounting threads: 1.25 inch filter thread or 28.5x0.75 mm on one sides; the opposite end of this adapter has a C-mount that is 1 inch diameter with 32 threads per inch standard for C or CS mount CCTV type cameras with telescopes;