Zoom driver: Horizontal axial drive control knobs, eyepieces: With high eyepoint and wide field eyepieces SWH10X(dia23mm), the diameter of fitting: 30mm, objectives: 1x/2x, 1x/3x, 2x/4x, working distance: 105MM, focusing range: 51mm, interpupillary distance adjsutment range: 54mm-76mm, diopter adjustment: +-5 degree. Light sources: The up light source is the reflected halogen lamp 6v 10w adjustable brightness, the low light is transmitted fluorescent lamp 5w.