The Nikon SB-900 Speedlight is Nikon's flagship flash unit, and the most advanced in the Speedlight range. As a replacement to the SB-800, the SB-900 shares many of the same functions, but also has some innovative additions and improvements. Its automated zoom head has been expanded to cover 17mm to 200mm lenses (in 35mm/FX format), and can cover this range in just 1.2 seconds. This flash now lets you select from three light distribution patterns: Standard, Center-weighted, and Even. It will also automatically detect if it is connected to a DX or FX format camera, and adjust itself accordingly.

The SB-900 can work as a stand-alone flash, or as part of a wireless group, either in Commander mode or as a slave (remote). The i-TTL system in this flash supports Advanced Wireless Lighting and versatile functions for up to four groups of Speedlights, with 3 remote i-TTL Speedlight groups controlled through the master SB-900. i-TTL Balanced Fill-Flash flash control employs Nikon's Advanced Data Communication system. This system provides an improved method for the monitor pre-flash and wireless operation that marks an evolution in higher precision over Nikon's acclaimed D-TTL Balanced Fill-Flash control system, and forms the core of the Creative Lighting System.

• Multiple Flash Exposure Modes

• i-TTL Balanced Fill-Flash with Nikon cameras that support i-TTL (e.g. D3, D700, D200, etc.)
  
• [AA] Auto Aperture Flash
  
• [A] Auto Aperture Flash with many film SLRs, including the Nikon N55 (F55) and FM10
  
• [M] Manual Flash

• Bounce Capability

Flash head tilts down to -7° or up to 90°
Flash head rotates horizontally 180° to the left and right.

• i-TTL

Intelligent i-TTL system supports Advanced Wireless Lighting and versatile functions for up to 3 remote i-TTL Speedlight groups controlled through a master SB-900 or with the "Commander" function of compatible cameras.

• 3 Light Distribution Patterns

Allows you to improve the light quality by selecting Standard for general illumination, Center-weighted for portraits, or Even for groups and interiors.

• Stroboscopic Effect

Repeating flash for creating stroboscopic multiple-exposure effect.

• Mixed Exposure Modes

Individual flash mode settings ([TTL], [AA], [A] and [M]) are available for each of the four groups (including master controller) for easy total lighting control based on the brightness of the subject and not simply on general output ratios for each group.

• FV Lock

Flash Value Lock allows photographers to change the composition or zoom for the shot while maintaining desired lighting of the subject.

• Distance Priority Manual Flash Mode

User can set the distance and aperture, and the SB-900 automatically sets the power output, a great feature for manual flash [M] shooting at weddings and for product shots.

• Colored Gels

Allows modification of flash output to match background scene, especially useful for digital cameras where "white balance" can be controlled. Included are Tungsten and Fluorescent adjustment filters.

• Color Gel Filter Identification

Flash automatically identifies mounted color gel filters and adjusts the camera's auto white-balance setting with select Nikon digital SLR cameras.

• Flash Tube Overheat Protection

Includes a built-in thermal sensor that protects the flash-tube from overheating during sustained high-speed bursts.

• AF-Assist Illuminator

The SB-900 provides improved AF assisting accuracy by being able to cover all 51 AF points with the D3, D700, and D300 (as of 7/2008), and with wider coverage from 20-105mm.

• Firmware Updating

Allows uploading of performance enhancement developments to the SB-900 with select Nikon digital SLR cameras.

• LCD

Large easily read illuminated LCD panel.