OPERATIONZEISS Illumination and contrast methods in transmitted light Axiolab 582 430037-7444-001 05/2019• Close the luminous-field diaphragm (Fig. 4-3/5)until it is visible (even if not in focus) in the fieldof view (Fig. 4-3/A).• Turn the vertical control of the condenser driveto lower the condenser until the edge of theluminous-field diaphragm appears in focus(Fig. 4-3/B).• Center the luminous-field diaphragm using thetwo centering screws (Fig. 4-3/4) on thecondenser carrier (Fig. 4-3/C) and then open theluminous-field diaphragm until the edge of thediaphragm just disappears from the field ofvision (Fig. 4-3/D).• To adjust the aperture diaphragm (contrast),remove an eyepiece from the eyepiece tube andlook into the tube with the naked eye. Set theaperture diaphragm with the adjusting lever(Fig. 4-4/4) to between 2/3 - 4/5 of thediameter of the exit pupil of the objective(Fig. 4-3/E). In most applications, this aperturediaphragm setting provides optimal contrast atalmost ideal resolution, and is therefore the bestcompromise for the human eye.• Reinsert the eyepiece into the eyepiece tube.NOTEEvery change of objective will result in a change in specimen field size and objective aperture,together with a possible slight change in centering, so that for optimal results the luminous-field and aperture diaphragm adjustments must be repeated.With objectives < 10x, the front lens of the condenser (if swivelable) must be swiveled out ofthe beam path and the aperture diaphragm completely opened. For better contrast with suchlarge object fields, the luminous-field aperture should be closed to a certain extent.Overclosing should be avoided so as not to impair the uniformity of the illumination of thefield of view.Fig. 4-3 Microscope settings in transmittedlight brightfield microscopy
