... with a fine focus of a large objective lens (adjustable 20mm), optional 250mm apochromatic objective. 3, the primary mirror with a ... 16.5mm, Φ10.4mm4, eyepiece 12.5 X / 18B5, large objective lens focal length: 250mm (optional 200,300,350,400)6 ... 50Hz or 110V/60Hz...Optional splitter, single head teaching microscope, binocular assistant microscope, internal or external camera and interface, and digital ...