Canon Speedlite 430EX III-RT review

The latest Mk III edition of Canon’s ever-popular flashgun is full of great tricks, with radio triggering and intuitive controls

Canon Speedlite EX 430EX III-RT
(Image: © Matthew Richards)

Digital Camera World Verdict

The 430EX III-RT packs plenty of high-end features into a compact and lightweight package. However, the lack of an optical wireless master facility or stroboscopic multi-flash mode are disappointing.


  • +

    Intuitive interface with four-way pad with a rotary dial

  • +

    Good value

  • +

    Built-in radio trigger

  • +

    Excellent exposure


  • -

    Modest maximum output

  • -

    No AF assist beam with EOS R system

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The third generation of the Canon's most popular flashgun takes on from the Speedlite 430EX and 430EX II. Launched in 2015, the Canon Speedlite 430EX III-RT packs the same powerful punch but adds plenty of new thrills. The most clearly visible differences are around the back.

(Image credit: Matthew Richards)

The control panel is based on intuitive buttons and a rotary dial/multi-way pad. The main on/off lever also features a Lock position to avoid any accidental adjustments. Status is shown on an illuminated mono LCD screen. (Image credit: Matthew Richards)

The illuminated info LCD screen is larger and clearer, while on-board controls are simpler and more intuitive, making flash menu options easily accessible and quick to adjust. Whereas the Mk II’s swivel function only worked up to 180 degrees to the left and 90 degrees to the right, the Mk III extends 150 degrees to the left and a full 180 degrees to the right.

There’s zero to 180 degrees of vertical bounce, 150 degrees of swivel to the left and a full 180 degrees of swivel to the right. The locking button shown here on the side of the flash head needs to pressed in to release it from its standard position, with no bounce or swivel. (Image credit: Matthew Richards)

The head also retains a slide-out wide-angle diffuser but also adds an extending reflector panel, useful for adding catch-lights in the eyes during bounce flash portraiture. Manual power settings now descend to 1/128th instead of just 1/64th, better for close-up shooting.

A pull-out catchlight card and spring-loaded wide-angle diffuser panel are housed in the top of the flash head. (Image credit: Matthew Richards)


Max claimed Gn (ISO 100, metres)  43

Bounce 0 to 90°

Swivel (left/right) 150 / 180°

Zoom Range 24-105mm (auto)

Wide-angle Diffuser 14mm

Reflector card Yes

Auto Metering E-TTL / E-TTL II

Flash Exposure Comp +/-3EV

Manual Power Settings 1/1 to 1/128

AF-assist beam Red lamp

Secondary lamp No

Wireless Master/Slave RF

Additional Flash Modes HSS, RC 

TTL flash exp error 0EV

Full Power Recycle (NiMH/alkaline) 2.4/3.4 seconds

Flash Info LCD Yes

Supplied accessories Pouch, foot, dome, filter

Dimensions (WxHxD) 71x114x98mm 

Weight (excl batts) 295g


The Speedlite comes complete with a diffusion dome, color filter and tabletop stand that has a tripod mounting socket in its base. You also get a soft case for the flashgun and stand, plus a smaller bag for the diffusion dome and filter. (Image credit: Matthew Richards)

The Mk III has a better range of extras as well. You still get a smart carrying pouch and a mini stand for off-camera flash, but new additions include a clip-on diffusion dome and a color balance filter for matching the flash with tungsten/incandescent lighting. Similar to an independently made Sto-Fen Omni-Bounce, the diffusion dome is great for softening the quality of light (see example shots). Better still, when you clip the official Canon dome to the 430EX III-RT, the flashgun automatically registers its presence and makes the appropriate adjustments, for example zooming the head to its most wide-angle setting.

A diffusion dome is supplied with the Speedlite. When clipped on, it enables a balance of direct and reflected light, from white walls or a ceiling, which often gives a more natural looking result. (Image credit: Matthew Richards)

The Speedlite comes complete with an orange color filter. When fitted, this balances the color temperature of the flash with tungsten ambient lighting. You can use the filter and the diffusion dome simultaneously, as the dome can fit over the top. (Image credit: Matthew Richards)

A top feature of the new Mk III is that it inherits RF (Radio Frequency) wireless connectivity from Canon’s range-topping Speedlite 600EX-RT flashgun. Compared with optical wireless mode, this boosts the range of off-camera flash from 10m to as much as 30m, and adds the ability to communicate through obstacles and even around corners, as no ‘line of sight’ is required. It’s a much more sophisticated system for lighting setups based on multiple flashguns with RF capability.

The underneath of the flash head has keyed detection sites, so the Speedlite ‘knows’ when the color filter or diffusion dome are attached. (Image credit: Matthew Richards)

To maximize wireless compatibility with cameras and other flashguns, optical slave functions are also available. These enable you to fire the flashgun remotely (off-camera) using the pop-up flash of recent Canon DSLRs as a wireless master, or to trigger the 430EX III-RT from another flashgun that has an optical wireless master mode.  

Thankfully the Mk III has an an optical master mode (unlike the Mk II). So, if you already own a 430EX II and you buy an additional 430EX III-RT, you can combine them in a wireless master and slave configuration.

The pop-up flash on camera gives a harsh quality of light, often with glare and unsightly shadows (Image credit: Matthew Richards / Digital Camera World)

The 430EX III-RT’s diffusion dome softens the light and reduces shadows for more natural results (Image credit: Matthew Richards / Digital Camera World)


Typical of most flashguns, the Speedlite runs on four AA batteries. As usual, stamina and recycling speed is enhanced if you use rechargeable Ni-MH batteries instead of regular alkaline cells. (Image credit: Matthew Richards)

In our tests, swift recycling speeds proved very marginally faster than those of the Mk II. The maximum output is essentially the same, although we found the full-power flash at the 105mm zoom setting to be very slightly more intense. Flash exposure accuracy in E-TTL II mode remains spot-on in wide-ranging conditions. 

Build quality feels solid and robust. The Speedlite isn’t weather-sealed but it does feature a metal rather than plastic mounting plate and a locking lever which is quicker and easier to use than a thumbwheel. (Image credit: Matthew Richards)

Lab tests

(Image credit: Future)

Power output: The Canon 430EX III-RT is a powerful performer (based on one metre distance at ISO100)

(Image credit: Future)

Recycle speed is fast (as usual, it’s faster using NiMH, rather than alkaline, cells)

(Image credit: Future)

TTL exposure accuracy: E-TTL II flash metering is usually spot-on, at a range of distances and zoom settings 

How we test flashguns

At DCW, our in-house team of experts are well-versed in testing cameras, lenses and accessories. We review equipment such as flashguns using a combination of real-world and lab testing, rating the power output of the flash, its versatility, its key features and its ease of use. We use our findings from reviews to inform our comments in buying guides. For more, see our guide to how we test and review at Digital Camera World.

Read more:

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The 6 best LED light panels 
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Matthew Richards

Matthew Richards is a photographer and journalist who has spent years using and reviewing all manner of photo gear. He is Digital Camera World's principal lens reviewer – and has tested more primes and zooms than most people have had hot dinners! 

His expertise with equipment doesn’t end there, though. He is also an encyclopedia  when it comes to all manner of cameras, camera holsters and bags, flashguns, tripods and heads, printers, papers and inks, and just about anything imaging-related. 

In an earlier life he was a broadcast engineer at the BBC, as well as a former editor of PC Guide.