NSL Photography's™ Glossary of Photographic Terms - W

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White Balance
White balance is a function on the camera which allows it to compensate for different colors of light being emitted by different light sources.

Wide Angle Lens
In photography and cinematography, a wide-angle lens is a lens whose focal length is substantially shorter than the focal length of a normal lens for the image size produced by the camera, whether this is dictated by the dimensions of the image frame at the film plane for film cameras or the dimensions of the photosensor for digital cameras.

Many DSLR interchangeable lens cameras have photosensors which are smaller than the film format of full-frame 35 mm cameras. For the most part, the dimensions of these photosensors are similar to the APS-C image frame size, approximately 24 mm x 16 mm. Therefore, the angle of view for any given focal length lens will be narrower than it would be in a full-frame camera because the smaller sensor "sees" less of the image projected by the lens. The camera manufacturers provide a crop factor (sometimes called a field-of-view factor or a focal-length multiplier) to show how much smaller the sensor is than a full 35 mm film frame. For example, one common factor is 1.5 (Nikon DX format and some others) The 1.5 indicates that the angle of view of a lens on the camera is the same as that of a 1.5 times longer focal length on a 35 mm full-frame camera, which explains why the crop factor is also known as a focal-length multiplier. For example, a 28 mm lens on the DSLR (given a crop factor of 1.5) has the angle of view of a 42 mm lens on a full-frame camera.

Lens manufacturers have responded to this problem by making wide-angle lenses of much shorter focal lengths for these cameras, but in doing this, they limit the diameter of the image projected to slightly more than the diagonal measurement of the photosensor. This gives the designers more flexibility in providing the optical corrections necessary to economically produce high quality images at these short focal lengths, especially when the lenses are zoom lenses, however, these lenses cannot be used to light full 35mm sized sensors, such as the Nikon FX sensor.

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