Parfocality means that when one objective lens is in focus, then the other objective lens will also be in focus. Pay attention to the diopter settings on each ocular. Plus, know your own prescription. In addition, if the diopters are not set properly, you could be “in focus”, but your assistant using the side observer and/or the monitor image will be out of focus.
Personal Parfocal adjustment:
It’s critical that you obtain your own personal parfocal settings. Here’s how:
A. Position the microscope above a flat, stationary surface.
B. Using a pen or pencil, makes a dot on a piece of white paper to serve as a focus target and place it within the illumination field of the microscope.
C. Set both of the eyepiece diopter settings to “0”.
D. Set the microscope on its highest magnification setting and focus until a sharp image is obtained. Adjust the inter-pupillary distance so that “one” image is viewed
E. Being careful not to physically shift the microscope position, change the magnification setting to its lowest position. Then, focus left and right eyepieces, one at a time, by turning the diopter ring until the image is clear and sharp. Tighten the diopter lock button to lock in this position and record the settings for future use.
F. Each operator will then have their particular settings which are to be dialed in whenever that particular operator uses the microscope.
This procedure does not have to be repeated by the same operator each time the microscope is used. However, due to changes in eye correction associated with time, it is recommended that this procedure be repeated by the operator once or twice per year.