Lens hood

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Glossary Terms
Screw-fit and clamp-on accessory lens hoods

A Lens hood (sometimes called a lens shade) is a shade placed around the front of a lens to keep out light from outside the subject area, particularly strong light from the sun or artificial lighting. Such light, if allowed to fall on the lens surface, can enter the lens and, by reflecting from its internal surfaces, become flare (non image-forming light in the image area). This leads to a false increase in the brightness in shadows, and so reduces the image contrast. Lens hoods are needed especially where lenses are not protected by being recessed into the lens barrel or camera body.

A lens hood may be attached using a filter thread inside the rim of the lens, or push-fit to the outside of the lens barrel, or attached with a bayonet fitting, or may be built into the lens barrel. Most hoods are circular, but some are rectangular - matching the shape of the frame. A hood for a wide-angle lens may be formed of four 'petals', cut away at the corners so as not to intrude into the image. Some hoods are collapsible (perhaps by being made of rubber), so that they can be left in place while the camera is in a case. Large-format (and some medium-format) studio cameras may use a compendium hood; a short bellows which can be adjusted to suit the lens in use, using the ground glass screen to check the hood does not intrude into view.

The lens cap of the Werra... can be removed, flipped around and... (with the end cap removed) used as a hood.