This camera node provides a perspective view, like a regular camera. This is the 'standard' camera type that you will probably use most often. In addition to normal perspective, this camera type also provides controls for depth of field, and the focal length of the camera, as well as controls, to do with the aperture of the camera. This allows various camera lens effects, including bokeh, to be simulated.
The cameras page has more details about the controls.
Radial distortion, with negative and positive values resulting in pincushion and barrel distortion respectively. Real world lenses can show such distortion when using, for example, a very short focal length or a high zoom.
Radial Distortion (-1.3 to 1)
A 'barrel distortion' camera lens effect has been reproduced in the interior scene below, by simply increasing the Radial Distortion to 0.2 (rollover image).