Lens assembly with switched ultra-narrow field-of-view configuration

A lens assembly comprising:

• a housing defining an interior volume having a substantially linear optical axis extending therethrough;
• a first lens disposed in the housing on the optical axis;
• an aperture mechanism disposed in the housing on the optical axis, the first lens and the aperture mechanism defining an optical path segment therebetween;
• a zoom group disposed in the housing on the optical axis in the optical path segment, the zoom group movable between a plurality of field-of-view (FOV) positions along the optical path segment;
• and
• an ultra-narrow field-of-view (UNFOV) lens group movable between a first UNFOV position outside the optical axis and a second UNFOV position on the optical axis in the optical path segment;
• the lens assembly having a plurality of FOV configurations each comprising the zoom group disposed at one of the plurality of FOV positions, and wherein the UNFOV lens group is in the first UNFOV position;
• and
• the lens assembly having a UNFOV configuration comprising the zoom group disposed at one of the plurality of FOV positions, and wherein the UNFOV lens group is in the second UNFOV position.