Canon EW-73B Lens Hood For 17-85mm f/4-5.6 IS EF-S and 18-135mm f/3.5-5.6 IS Lenses

Lens hoods are designed to prevent unwanted stray light from entering the lens. They do this by extending and shading the end of the lens and since the end of the lens is extended, you also achieve the added benefit of some extra protection from accidental impact.

This lens hood maximizes the amount of hood coverage for the minimum amount of weight and hood area because of its "petal" shape. This dedicated lens hood is specifically designed to match the exact focal length of the lens it was designed for.

The addition of a lens hood can help prevent flares--those circles of light that can accompany images where a strong light source is just outside the fame. These type of lens flares occur when indirect light rays pass through the front lens elements but don't make it all the way through to the image sensor. Canon's EW-73B Lens Hood is designed for the Canon EF-S 17-85 f/4-5.6 IS USM SLR Lens.