What is Nikon's "Creative Lighting System" (CLS)?

Nikon has created a new communication method used by the latest Speedlights which offer improved flash system functionality and better flash exposure, known commonly as the Creative Lighting System (CLS). Both the digital camera and Speedlight used must be CLS compatible for the functions listed below to work, the availability of each function depends on the products used.

The D70 / D2H cameras and the SB-600 / SB-800 Speedlights use the new communication system necessary for CLS compatibility, if a CLS compatible product is used with a non-CLS compatible product then the new functions listed will not be available.

New Creative Lighting System flash functions:
i-TTL flash control
Provides a stronger, shorter pre-flash than is available with D-TTL making it easier for the camera to calculate the correct metering of foreground and background.
FV Lock
Metering is concentrated on a small area of the image after FV-Lock is applied. Flash output level is compensated to produce the same exposure even when shutter speed, aperture, ISO sensitivity and zoom settings are adjusted.
Auto FP high-speed sync
High speed flash synchronization is applied based on the camera's shutter speed (e.g.. D2H above 1/250th of a second). Normally when flash is used a small aperture setting is chosen (high f-stop setting), this has the effect of producing a wide depth of field. Using a series of flashes instead of one main flash the camera can use a large aperture (low f-stop setting) producing a narrow depth of field.
Flash color information communication
When a CLS compatible Speedlight and camera are connected and powered ON, datacontaining flash spectrum informationis transmitted to the camera. Also flash duration and charge voltage information is transmitted to the camera after the flash, this information is used to control image white balance more precisely.
1.2.Wide-area AF-assist illuminator
Supports even illumination all focus points used by cameras using wide-area AF-assist illuminators.
Advanced Wireless Lighting
New method of communication for controlling multiple wireless flash units. The 'master' sends out a series of very small light pulses to provide the 'slaves' and they communicate back subject exposure readings before the main exposure. Effective wireless range is 10m (33ft) and 30 degrees left or right of the 'master' at longest distance, 60 degrees at closer distances. Advantages of this system are that many remote flash untis can be controlled at the same time and positioning becomes easy allowing for more photographic freedom.