The invention contemplates {TAIL ~ a precisely adjustable threaded mechanism}, as for focus adjustment of an aerial camera lens, wherein inner and outer threaded members are normally in circumferentially continuous radially stressed play free engagement to {HEAD ~ the extent} of requiring a characteristic maximum torque for their rotary adjustment 
The invention contemplates { TAIL ~ a precisely adjustable threaded mechanism } , as for focus adjustment of an aerial camera lens , wherein inner and outer threaded members are normally in circumferentially continuous radially stressed play free engagement to { HEAD ~ the extent } of requiring a characteristic maximum torque for their rotary adjustment
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