Helps block unwanted light Lens hoods are essential when taking pictures where the camera is pointing towards a strong source of light (i.e. the sun, spot lights). Protects the lens Protects the lens when stood on a surface, in the camera bag, or when changing lenses - also helps to keep fingers away from the front of the lens. Compatible Lens hood for Alpha SEL1855/SEL28F20/SEL35F18 lens.