A particularly important feature of the TRM-301 is its ability for the Köhler illumination. This optimal illumination unbeatably bright, cool (specimen friendly), homogenous, reflex free and rich in contrast makes full use of the microscope's advanced optics. The Köhler illumination is standard for scientific research and microphotography. One gets it using the fixed field diaphragm and the height- and center-adjustable Abbe condenser (numerical aperture 1.25; with iris diaphragm). Naturally, the TRM-301 has other features, which are typical for high-quality microscopes: lengthwise and cross moveable stage, ergonomic coaxial focusing knobs (concerning fine drive: 200 mm / full turn), continuous dimmer, planachromatic objectives (4x, 10x, 40x, 100x-oil retractable), 10x wide field eyepieces (mounted in 30° inclined eyepiece tubes), adjustment of eye relief, dioptre adjustment and the phototube.