A lens hood does a couple of jobs. It stops unwelcome stray light from getting into the lens, by acting as an
extension and shades the front of the lens. Additionally, there's an extra advantage of some optional protection if the lens is bumped or dropped.
Also a lens hood attached to the front of your lens will protect your images from lens flare. Lens flare typically occurs when your point your lens at a bright light source.
Flare can occur from internal refraction and reflection of light reaching your lens's optical components. It could be that the sun is overly bright for the camera lens, which might easily spoil your photo. When your lens has bright light shining on it, although not in your field of view, resulting flare that is created is most often a haze which can wash out your image inside the camera image and subsequently reduce its contrast.
This effect can be avoided by shading the lens using a hood or holding your hand or other object between the light source and the camera lens. Doing this any glare will be effectively eliminated.
Buy Pearstone Lens Hoods at Adorama or
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Designed to fit lenses with a 52,
55, 58, 62, 67, 72, 77 and 82mm, filter threads. The hoods work best with lenses with an 18 to 105mm focal length. With wider lenses, especially on full frame cameras, some slight vignetting
might occur. The "petal" shape of these lens hoods maximizes the amount of hood coverage with the minimum amount of weight and hood area.