The Norwegian website Akamera.no has tested the Canon 17-40mm f/4 L zoom lens, which sells for around ?600 in the UK, against the Canon EF-S 18-55mm f/3.5-5.6 lens and 3 Canon prime lenses. The article is worth looking at even if you can’t speak Norwegian, as there are a lot of comparitive sample images.

Website: Akamera.no - Canon Zoom Lens Test