Aspects of the present disclosure relate to external user interfaces used in connection with head worn computers (HWC). Embodiments relate to an external user interface that has a physical form intended to be hand held. The hand held user interface may be in the form similar to that of a writing instrument, such as a pen. In embodiments, the hand held user interface includes technologies relating to writing surface tip pressure monitoring, lens configurations setting a predetermined imaging distance, user interface software mode selection, quick software application launching, and other interface technologies.