Specifications Fieldmicroscope Magnification (x) 20x (fixed) Optical system Upright, unreversed image; eyepiece diopter adjustable for right eye; 56-to-72mm interpupillary distance adjustment Field of vision (mm) 11 (diameter) Angle of view (º) 12.6 Vertical adjustment 50mm from the base of stage Eye relief (mm) 11.1 Plate Removal and reversible (top: flat; underside: built-in cup) Light source 2.5V-0.5A halogen lamp Light settings On/off Power source CR 123A lithium battery; approx. 1-hour bat