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A lens cover or lens cap provides protection from scratches and minor collisions for 
A more secure lens cap is the metal screw-in lens cap which cannot pop off a lens accidentally. Although a screw-in cap takes more time to remove in order to take a photograph than a standard lens cap, it is stronger than plastic and therefore more protective.
Some cameras (mostly compact cameras) feature an automatic lens cap that opens when the camera is powered on, they often use plastic blades and thus do not offer much protection against damage.
Friction fit lens caps exist but are quite rare.
Lens caps or covers are often lost, they are not a high value item among photographers, especially professionals, photographers at large events or in large crowds may drop their lens caps and fail to retrieve them, leading to a litter of lens caps.
A lens cap may be tethered to the camera via a string to avoid losing it.
Aside from lens caps, there are also rear caps and body caps, these are used in interchangeable lens cameras and allow protection for the lenses rear element and the shutter/sensor of the camera in storage.
Lens caps are also used in mechanical and/or environmental protection for objective and ocular (outer) lens surfaces in other optical instruments like binoculars or microscopes.
camera
A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
and camcorder
A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-sw ...
lenses
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
. Lens covers come standard with most cameras and lenses. Some mobile camera phone
A camera phone is a mobile phone that is able to capture photographs and often record video using one or more built-in digital cameras. It can also send the resulting image wirelessly and conveniently. The first commercial phone with a color c ...
s include lens covers, such as the Sony Ericsson W800, the Sony Ericsson K750 and the Sony Ericsson K550.
A more secure lens cap is the metal screw-in lens cap which cannot pop off a lens accidentally. Although a screw-in cap takes more time to remove in order to take a photograph than a standard lens cap, it is stronger than plastic and therefore more protective.
Some cameras (mostly compact cameras) feature an automatic lens cap that opens when the camera is powered on, they often use plastic blades and thus do not offer much protection against damage.
Friction fit lens caps exist but are quite rare.
Lens caps or covers are often lost, they are not a high value item among photographers, especially professionals, photographers at large events or in large crowds may drop their lens caps and fail to retrieve them, leading to a litter of lens caps.
A lens cap may be tethered to the camera via a string to avoid losing it.
Aside from lens caps, there are also rear caps and body caps, these are used in interchangeable lens cameras and allow protection for the lenses rear element and the shutter/sensor of the camera in storage.
Non-photographic use
Lens caps are also used in mechanical and/or environmental protection for objective and ocular (outer) lens surfaces in other optical instruments like binoculars or microscopes.
See also
* Lens hoodReferences
Photography equipment {{Photo-stub