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How do you focus a slide under the oil immersion objective?
Place the slide on the stage and secure with the stage clips. Using the coarse adjustment, focus and center the image in the field of view under the low power objective. Once the image is focused, rotate the nosepiece to the high power objective and focus using the fine adjustment. Once the image is centered in the FOV, rotate the nosepiece to the oil immersion objective and focus using the fine adjustment.