Video Camera Filters
Camera filters are transparent or translucent optical elements which are either attached to the front of the lens or included as part of the lens housing. Filters alter the properties of light before it reaches the CCD.
Filters can be used to correct problems with light or to create certain effects.
Common types of filter include:
|Neutral Density (ND)||A colour-neutral filter which absorbs light evenly throughout the visible spectrum. Used to reduce the amount of light coming through the lens in strong lighting situations.|
|Ultra Violet (UV)||Video cameras are sensitive to both visible light and ultra violet (UV) light. UV is invisible to humans but it can create a blue tinge and/or washed-out effect on video, especially outside. A UV filter removes UV light while leaving visible light intact. UV filters are also commonly used as a protective filter for the lens.|
|Polarizing||A special type of lens which removes polarized light, reducing the washed-out effect sometimes created by reflected light. This results in more saturated, vibrant colours. Polarized filters are usually mounted with a rotational adjustment to align the polarization.|
|Diffusion||Effectively blurs the image for a slightly soft look. A mild diffusion filter can be used to soften faces (remove wrinkles etc), a stronger filter can be used to create a dream-sequence effect.|
|Sepia||Creates a sepia-tone effect, commonly used to depict historical images or flashbacks.|
|Fog||Creates a fog effect.|
|Colour Conversion / Correction||Adjusts the colour temperature of the light.|
|Star Effect||Makes single points of light stretch out in various star patterns. This effect is created by numerous fine etches in the filter, and can be used to give a dramatic, sophisticated or glamorous look to the image.|
Graduated Filters are graduated from one part of the filter to another, for example, a graduated ND filter might have a strong ND filter on one half and none on the other half. This could be used to frame an image which is half sky, if you only want the sky to be affected by the filter.
Graduated filters have varying levels of transition. A sharp transition means there is a well-defined line between different parts of the filter. With soft transitions, the graduation is smoother.