text: **OPERATION (cont.)**
  
  6. Adjust the interpupillary distance by using the eyepiece 
   interpupillary slide adjustment. 
  7. Observe using the right eyepiece adjusting the coarse and fine 
   focus and adjust the diopter ring until image is clear and sharp. 
  8. Observe with the left eyepiece and adjust the diopter ring until 
   image is clear and sharp. 
  9. Rotate the fine focus adjustment when using other objectives. 
   NOTE: This instrument is equipped with patent objectives so 
   the precision or parfocalization is very high. 
  
  **ADJUSTING THE CONDENSER APERTURE**
  
  1. The numerical aperture of the condenser should match the 
   numerical aperture of the objective being used. 
  2. To make sure that the objectives are imaging properly 
   (especially the 40x and 100x), follow this procedure: 
  
  1. Take off the eyepiece. 
  2. Look through the eyepiece. 
   3. The smallest circle or light that you can see is the 
  
   eyepiece's exit pupil. 
  4. Adjust the aperture of the iris diaphragm in the 
   condenser to 70% or 80% for the best contrast for 
   observation (See Fig. 2.). 
  
  Adjustable 
  Ring  Tightening 
  Ring  Mark 
  Sleeve  Front 
  Sleeve 
  
  Exit Pupil 
  of Objective 