Bresser Bioscience 40-1000x Trinocular Microscope

The Bioscience is a trinocular laboratory microscope from Bresser's Science series, for a teaching lab, clinic or research bench that wants Köhler illumination and a camera port at 40x to 1000x. Trinocular means a third tube above the two eyepieces, so a camera can stay fitted while people take turns at the eyepieces.

The four objectives are achromatic DIN lenses, 4x, 10x, 40x and 100x oil. Achromatic means red and blue light are brought to the same focus, which removes most colour fringing; DIN is the standard thread, so other DIN objectives fit. The eyepieces are a pair of WF10x/18 in 23 mm tubes, the 18 being the width of the view in millimetres. Under the stage sits an Abbe condenser with a numerical aperture (N.A.) of 1.25. The N.A. is how wide a cone of light it sends into the sample, and it has to match the 100x oil objective's 1.25 before 1000x shows full detail.

A 12 V, 30 W halogen lamp with a dimmer runs from a separate mains adapter and feeds a Köhler illuminator. Köhler illumination is a way of setting the lamp, field diaphragm and condenser so the field is lit evenly and the lamp filament never appears in the picture, the standard for photography through a microscope. Bresser says the halogen is bright enough for its optional phase contrast and dark-field kits. The coaxial mechanical stage has a Vernier scale, so a cell can be logged by its coordinates and found again, and focus has coarse and fine knobs on one axis.

The box holds both eyepieces, the four objectives, the condenser, immersion oil and a dust cover. A C-mount camera needs Bresser's optional adapter, and our microscope camera guide explains what fits a trinocular tube. The Bresser Researcher 40-1000x below it reaches the same magnifications on a smaller stand without Köhler, and the Science TFM-301 above it adds LED lighting, semi-plan objectives and dioptre adjustment on both eyepieces. The rest of our laboratory microscopes sit together.