Canon's affordable L-series ultra-wide zoom, a landscape favourite for nearly two decades.
The Canon EF 17-40mm f/4L USM was launched in 2003 as Canon's affordable ultra-wide L-series zoom. Covering 17-40mm on full-frame or 27-64mm on APS-C, it offered L-series build quality and weather sealing at a price well below the EF 16-35mm f/2.8L. It became the default wide-angle zoom for budget-conscious Canon shooters.
Optical quality is good with sharp centre performance and typical ultra-wide corner softness. Flare resistance is reasonable. Ring USM autofocus is fast and silent. Build is classic L-series with weather sealing, a metal mount, and the red ring. At f/4 it is one stop slower than the 16-35mm f/2.8L which limits low-light use.
Canon EF mount only, 77mm filter thread. The EF 16-35mm f/4L IS USM succeeded it in 2014 with image stabilisation and improved optics. The RF 14-35mm f/4L IS USM is the mirrorless equivalent. The original 17-40mm remains widely used.
Very good value used as one of the cheapest L-series lenses available. Check the zoom ring, USM motor, and weather seals. Inspect for front element damage. The 16-35mm f/4L IS is optically better but the 17-40mm remains a solid and affordable ultra-wide option.