Magnification 38x; objective 1 equals 700mm, effective aperture 70mm; darkfield for 6d; calibrations in viewfield and micrometer; measuring range 30 minutes of ar (on both vertical and horizontal axes) ; reading 0.5 seconds of arc; measuring accuracy 0.5seconds of arc measuring, 1.0 secons of arc for measuring range within 30 minutes of arc; light source 6v, 15w special electric bulb; power input 100-120v, 220-240v; 68.0 x 490mm body; 30kg