OPERATIONZEISS Illumination and contrast methods in transmitted light … Axioscope 5/7/Vario88 430035-7344-001 03/2018• Center the field diaphragm image with bothcentering screws (620HFig. 4-3/4) on the condensercarrier (621HFig. 4-3/C).• Open the field diaphragm enough to make theedge of the diaphragm disappear from the fieldof view (622HFig. 4-3/D).• To adjust the aperture (contrast), take aneyepiece from the tube barrel. Looking throughthe barrel adjust the aperture with the adjustinglever (623HFig. 4-4/4) of the aperture diaphragm tothe size of approx. 2/3 - 4/5 of the diameter ofthe objective exit pupil (624HFig. 4-3/E). In mostcases this aperture gives the best contrast atalmost full resolution and is thus the bestcompromise for the human eye.• Replace the eyepiece in the tube barrel.NOTEEach objective changes the size of the object field and the objective aperture. The centeringmight also vary slightly from objective to objective, so that an adjustment of field diaphragmand aperture might become necessary for optimal results.With objectives < 10x, the front lens of the condenser (if swivelable) must be swiveled out ofthe beam path and the aperture opened fully. In order to achieve a better contrast, the fielddiaphragm can be pulled closer when working with large object fields. To do this you mustreduce the opening by a certain range. Avoid closing it too much to guarantee a consistentillumination of the field of view.Fig. 4-3 Microscope adjustment intransmitted light brightfieldmicroscopy
