Among zoom lenses, it is known for excellent contrast, color rendition and sharpness, and it is widely considered[according to whom?] to be one of the finest wide-to-normal zoom lenses ever produced. Like many other zoom lenses, it exhibits some barrel distortion at the wide end of its range.
A unique aspect of the 28–70mm f/2.8L (and 24–70mm f/2.8L) is that its barrel extends as it zooms toward its shortest focal length. When used with the supplied "petaled" lens hood, which attaches to a non-moving part of the lens, this extension results in a properly matched shade at every angle of view. Most zoom lens hoods are designed for only the widest angle of view, offering progressively inadequate shade at longer focal lengths.