The coarse focus is used to locate the object at the lowest level of magnification (4x).
Once an object has been focused under 4x by using the coarse focus, the magnification level may be increased to the next power (10x).
Once the power is increased, you may SLOWLY AND CAREFULLY use the coarse focus to relocate the object.
Once the power is increased to 40x, the object should ONLY be focused using the fine focus.
If you attempt to use to use the coarse focus at 40x you risk breaking the slide.
If you must relocate the object or find a new object, return to the lowest power before using the coarse focus.
Using the coarse focus is the fifth step in using a microscope.