In addition to the two lenses, Canon also announced the Speedlite 430EX flash unit, which replaces Speedlite 420EX.

The Speedlite 430EX improves on many specifications of its predecessor, and includes new features to maximise digital image quality when using a flash. These include automatic selection of camera white balance settings, and auto-adjustment of the zoom flash position to match the sensor size of the camera to which the unit is attached. The Speedlite 430EX has increased its guide number to 43 (m/ISO 100 at 105mm), and has approximately 40% faster recycling time than the Speedlite 420EX.

An ultra-bright 2-LED configuration focus assist-beam has been designed to be compatible with all focus points within the frame of all EOS AF systems, up to 9-point AF.

The flash head zoom covers the range 24mm to 105mm and an integrated diffusion panel allows extended wide-angle coverage to 14mm. When attached to digital EOS cameras with smaller than full-frame sensors (such as the EOS-1D Mark II N, EOS 20D and EOS 350D) the Speedlite 430EX gives a more accurate flash coverage by detecting the model to which it is attached and automatically narrowing the angle of coverage. This has the effect of eliminating light loss in peripheral areas and extending the effective flash range.

The Speedlite 430EX automatically transfers colour temperature information to recent models of digital SLR cameras . The camera then sets the white balance optimally for the flash shot. This feature works when the camera's white balance mode is set to Auto White Balance (AWB) or Flash white balance mode.

The new flash unit is fully compatible with the distance linked E-TTL II system found on recent EOS cameras, and supports other EOS cameras that do not support E-TTL II, when required. For a complete multiple flash system, the Speedlite 430EX serves as a wireless slave when either the Speedlite 580EX, Macro Ring Lite MR-14EX, Macro Twin Lite MT-24EX or Speedlite Transmitter ST-E2 is used as a master.

Features include 1st and 2nd curtain flash synchronisation, and manual adjustment of flash output from full to 1/64 power (7 levels).

An optional Speedlite Bracket SB-E1 allows the flash unit to be mounted to one side of the camera. Designed specifically for press and wedding photographers, it eliminates the red-eye that can occur when mounting a flash on the axis of the lens, such as on the camera hot shoe. Flash batteries are replaceable without removing the unit from the bracket.