The focus system of a stereo microscope is usually composed of two knobs located on the sides of the microscope holder itself.
These two knobs are generally tightened so that the friction of the coarse focusing movement is adequate.
If the two knobs are turned in the opposite direction to each other, the friction is reduced and the stereo microscope drops by simple effect of gravity.
In this case it is sufficient to turn the two knobs in the opposite direction to the direction of rotation applied when the clutch is loosened, to reset the microscope.
Note that too high a clutch may cause malfunction due to excessive friction between the pinion and rack of the focusing assembly

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