Instruments used in minimally invasive medical procedures often need to provide complex operational capabilities within a limited instrument diameter. For example, a catheter used for a lung biopsy may be navigated along airways or bronchial tubes to a worksite in a patient's lung and then used as a guide for insertion and removal of other instruments such as a biopsy needle. However, a lung catheter will generally require more functionality than a simple guide tube in order to be usable. For example, to navigate airways, the lung catheter may need to be steerable, e.g., contain a mechanical system that allows remote control of the shape of the catheter and may need to include a system for determining the location of the catheter relative to natural lumens being navigated. Sensor systems using electromagnetic sensors or fiber shape sensors can be employed in the walls of a lung catheter to measure the location and pose of the catheter, which may be particularly useful for robotic or computer assisted operation of the catheter. A vision system that shows the interior of the airways, e.g., at the distal tip of the catheter, could also be useful during and after airway navigation. However, a vision system that provides a desired field of view can be challenging to accommodate within a catheter, particularly because the lumen of the catheter that guides instruments may occupy most of the center of the catheter and because the distal end of a lung catheter may be about 3 mm in diameter and have walls less than 1 mm.