National 440 Series Zoom Stereo Microscope

National 440 Series Zoom Stereo Microscope. The 440 Series is a professional-quality stereo microscope for industrial and educational settings. The large zoom ratio of 6:1 and a standard working distance of 110mm provide the flexibility to support a large number of potential applications while the addition of an auxiliary lens or substitute eyepieces extend the magnification up to a maximum of 180X. MAGNIFICATION 0.75X to 4.5X Zoom (7.5 - 45X Magnification) OPTICAL SYSTEM Paired widefield 10x eyepieces 45° inclined, with dual diopter adjustments Interpupillary adjustment from 55mm to 75mm Accepts 23mm eyepiece reticle. Viewing head rotates 360°. Continuous magnification from 7.5x thru 45x.  FOCUSING Large dual focusing knobs with slip clutch to prevent damage to mechanism. Tension adjustment eliminates focus 'drift'. PLAIN STAND ILLUMINATION None PLAIN STAGE No Stage Clips POST STAND ILLUMINATION Top light is LED with directional beam and rheostat control. Bottom light is L