This is a classic "one-touch" zoom lens from Nikon’s Series E line. Launched alongside the Nikon EM, the Series E lenses were designed to be more affordable and lightweight than the professional Nikkor line, but they earned a massive following for their excellent optical quality. This specific model is highly regarded because it maintains a constant f/4 maximum aperture throughout the entire zoom range—a feature usually reserved for much more expensive lenses. It uses a "push-pull" mechanism: you slide the large rubberized ring forward and back to zoom, and rotate it to focus.