The phenomenon of halos around highlights in an image. The effect is produced when light is reflected back from the back of the film-base. Film bases are consequently given a light-absorbing coat known as an anti-halation back to reduce or prevent the effect.
The brightest part of an image, particularly when specular or causing notable over-exposure.
In digital photography, a statistical representation of the number of pixels of a particular value plotted against the range of possible values.
A reasonably standardized connector found on the top of a camera designed to link with electronic flashguns.
The perceived colour of light, for example red or blue. Hue varies with wavelength. Colour is characterized by hue, saturation and lightness.
The action of an autofocus lens which is, for one of a variety of reasons, unable to achieve a point of sharp focus. This may occur when the contrast or light level is low. Lens focus shifts continually, or hunts, between distant and close-up limits.