Photo graphy:

Focus - the adjustment to place the sharpest focus where it is desired on the subject.

 Aperture – adjustment of the iris, measured as f-number, which controls the amount of light passing through the lens. Aperture also has an effect on focus and depth of field, namely, the smaller the opening aperture, the less light but the greater the depth of field--that is, the greater the range within which objects appear to be sharply focused. The current focal length divided by the f-number gives the actual aperture size in millimeters.

 Shutter speed – adjustment of the speed (often expressed either as fractions of seconds or as an angle, with mechanical shutters) of the shutter to control the amount of time during which the imaging medium is exposed to light for each exposure. Shutter speed may be used to control the amount of light striking the image plane; 'faster' shutter speeds (that is, those of shorter duration) decrease both the amount of light and the amount of image blurring from motion of the subject and/or camera.

 White balance – on digital cameras, electronic compensation for the color temperature associated with a given set of lighting conditions, ensuring that white light is registered as such on the imaging chip and therefore that the colors in the frame will appear natural. On mechanical, film-based cameras, this function is served by the operator's choice of film stock or with color correction filters. In addition to using white balance to register natural coloration of the image, photographers may employ white balance to aesthetic end, for example white balancing to a blue object in order to obtain a warm color temperature.