How long do camera lenses typically last, including Canon L and USM lenses?

Well-cared-for lenses usually last a very long time—often decades. In practice, accidental damage, heavy professional use, moisture/mold, or impact are more likely to end a lens’s life than simple age.

The optics and metal parts generally do not “wear out” quickly. For modern autofocus lenses, the main long-term concerns are electronic parts and motors; components such as capacitors can age over time. Fully mechanical/manual lenses can potentially last even longer because they depend less on electronics.

Canon L lenses are not defined by a fixed lifespan, but their build quality may help them survive use better and make repair more worthwhile. Some electronically dependent designs, such as focus-by-wire lenses, may become unusable if their electronics fail.

A reasonable expectation for a well-maintained autofocus lens is 10–20+ years, and many lenses remain usable far longer. In short: lenses usually become obsolete, incompatible, or accidentally damaged before they simply “wear out.”