Embodiments of an apparatus comprising a base including a proximal end, a distal end, and a receptacle in the distal end that is adapted to interchangeably receive a lens adapter; a set of base optics positioned in the proximal end of the base; and adjustable-focus optics positioned in the base and optically coupled to the base optics and, when the lens adapter is present, to the lens adapter. Embodiments of a process including forming a base including a proximal end, a distal end, and a receptacle in the distal end that is adapted to interchangeably receive any one of a plurality of lens adapters; positioning a set of base optics in the proximal end of the base; and positioning adjustable-focus optics positioned in the base such that they are optically coupled to the base optics and, when the lens adapter is present, to the lens adapter. Other embodiments are disclosed and claimed.