Positioned below the Canon 580EX and 600EX high-end Speedlites, the 430EX is geared toward amateurs who want to go beyond their pop-up flash and professionals who are looking to add an extra secondary flash.
Like the 600EX-RT, the 430EX III-RT can work with both radio and optical transmissions, but it’s limited to receiving signals as a slave for optical signals. For radio transmission, the flash can trigger other units as a master.
Another new feature introduced to the 430EX line is the addition of an SCF-E2 Color Filter for balancing color while shooting under incandescent lights, along with an SBA-E2 Bounce Adapter for softening light and suppressing shadows, and a built-in Catchlight panel
Other features of the 430EX RT-III include an illuminated dot-matrix LCD, a new control dial, light distribution options, multi-camera sync shooting, 10 custom functions and 8 personal functions, and remote shutter release.
The head of the flash tilts upward 90 degrees and can be rotated 150-degrees to the left and 180-degrees to the right.
Compared to the 430EX II, the new 430EX III-RT is both smaller and lighter, measuring 2.8×4.5 x3.9 inches instead of 2.8×4.8×4.0 inches, and weighing 10.41 ounces instead of 11.29oz. The unit is still powered by four AA batteries.
Additional specs of the unit include a shorter recycling time (0.1-2.5), faster firing, a maximum Guide Number of 43/141 at ISO 100 (in meters/feet, same as the 430EX II), Hi-Speed Sync, Second-curtain Sync, auto zooming from 24-105mm, and a metal locking foot.
The new Canon Speedlite 430EX III-RT will be available in September 2015 for the price of $300.
Update: Canon has sent out a correction stating that the 430EX III-RT can function as a master unit in RT mode. We’ve updated this post to reflect that, as we previously stated that it can only be used as a slave unit.