Thursday, June 19, 2008

Lens Hood

Lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare.

The geometry of the lens hood can vary from a plain conical section (much like a lamp shade) to a more complex cut sometimes called a flower, petal or tulip hood (as shown in the picture), which prevents the hood from blocking the field of view of the lens and producing vignetting. Flower shaped lens hoods are most often used on zoom lenses as a normal lens hood may block the field of view on some zoom settings.

Lens hoods are more prominent in telephoto lenses because the field of view has a smaller viewing angle than of wide-angle lenses. For wide angle lenses, the length of the hood (away from the end of the lens) cannot be as long as those for telephoto lenses because of the viewing angle.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space.

In addition, they offer some level of protection for the lens due to the hood extending farther than the lens itself.

Lens without and with hood

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