(7) To focus, look through the eyepieces and slowly turn the coarse adjustment knob until the specimen comes into view (moving the slide if necessary to center the specimen).  You may have to use the diopter adjustment ring on the left eyepiece to get both eyepieces in focus.  To do this, first get the specimen in clear focus using the non-diopter (right) eyepiece, closing the other eye if necessary.  Next, using the diopter adjustment ring, bring the left eyepiece into focus.  At this point both eyepieces should be correctly adjusted.

You may have noticed while performing the above procedure that the right eyepiece is provided with a pointer.  If at any time you have a question about a cell, structure, tissue, etc. you can indicate the object of interest to your instructor by moving it under the pointer with the mechanical stage knobs.

(8) Once again, adjust the light intensity to a comfortable level by using rotary switch and/or iris diaphragm as necessary.  At this point you should also turn the knob that controls the substage condenser to achieve the clearest possible image (the condenser focuses the incoming light on the specimen). 

(9) If you wish to view a specimen under high power, first make sure that the object is in focus under low power and centered in the field, then rotate the high power objective into place while visually checking to see that the tip of the objective will clear the slide.  Since most  microscopes are parfocal (an object in focus under low power will be in focus under high power), you only need to use the fine adjustment knob to complete the focusing process.