This document discusses various lens operations and controls including focal length, f-stops, lens speed, iris, macro lenses and focus, zoom lenses, wide angle lenses, depth of field, angle of view, zoom and zoom ratio, filters, and image stabilization. Focal length determines the distance between the lens and its focus point. F-stops correspond to aperture settings and lens speed refers to maximum aperture diameter. Macro lenses can produce life-size images and zoom lenses allow smooth changes between long and close-up shots. Wide angle lenses exaggerate depth and size while depth of field is the range of focus. Angle of view depends on focal length and sensor size. Zoom and zoom ratio determine the visible scene area. Filters include