After sliding into corresponding objective magnification such as Dispersion 10X or U plan Phase 40X, remove one eyepiece, replace with Centering Telescope, then using two centering screws, please align the ring slit to match the phase plate of the objectives.
Rotate the 10X objective into the working position. Close the "Iris Adjustment" by cranking the knob all the way to the left. When looking into the eyepieces, one will see the aperture hole of the diaphragm. It may or may not be centered in the field of view or FOV. You may also need to focus the microscope so the edges of the aperture hole are clear to see.
Place each hand on each of the "Condenser Centering Screws" while at the same time, looking into the eyepieces and adjusting the centering screws until the aperture hole is in center of the FOV.
When centered, the aperture will be in the center of the field of view as demonstrated in the picture above.
Next, remove the right eyepiece and in its place, insert the centering telescope. The top of the centering telescope has a focus adjustment which will be held in one hand with the other hand holding the body. While looking into the centering telescope, adjust the focus so you may get a sharp image of the phase annuli to be adjusted.
When the annuli are not aligned, one will see an image similar to the picture above: one light right is not aligned with the other.
After sliding into corresponding objective magnification such as Dispersion 10X or U plan Phase 40X, remove one eyepiece, replace with Centering Telescope, then using two centering screws, please align the ring slit to match the phase plate of the objectives.