Canon Speedlite 430EX III-RT Flash Review

Canon Speedlite 430EX III-RT Flash
In-Depth Review

With the introduction of the Speedlite 600EX-RT, one thing was inevitable – more radio-enabled flashes from Canon should be expected. Surprisingly, the 600EX-RT remained Canon's only radio-enabled flash for more than three years. The (seemingly long overdue) introduction of the Speedlite 430EX III-RT means that Canon's mid-range flash lineup has finally received its much-anticipated refresh. While radio functionality was a reasonable expectation in the 430EX II's replacement, the biggest surprise in the 430EX III-RT's announcement was the flash's ability to act as a radio master flash. Now budget-conscious consumers who do not require the higher power of the 600EX-RT have a lower-cost, smaller and lighter, yet full-featured alternative with the ability to control other off-camera flashes.

The Canon Speedlite 430EX III-RT is an upgrade to the Canon Speedlite 430EX II. Here is a list of upgraded and new features:

  • Smaller and lighter
  • Radio master and slave wireless remote control capabilities vs. none (both have optical slave capability)
  • Radio wireless remote has twice the range of optical wireless remote and does not have line-of-sight or angle-of-view requirements for both master and slave units
  • Remote Release and Linked shooting capabilities
  • Increased head rotation capabilities
  • Manual power settings available in 1/3 stop increments down to 1/128 power vs. 1/64
  • Larger and easier to read dynamic LCD display vs. fixed-segment display
  • 10/8 custom/personal functions vs. 9/0
  • Color filter included vs. 3rd party accessory
  • Included bounce adapter vs. none
  • Lock settings position featured on power switch
  • Green and orange LCD backlight colors settable by custom function vs. fixed color
  • Supports flash settings by camera menu (EOS 1D X, 5D Mark III and later than 2012-introduced DSLRs support full 430EX III-RT feature set)

Arguably the most alluring feature upgrades found in the 430EX III-RT will be the addition of radio triggering and the ability to act as a radio master flash. For many, those features alone will justify the cost of upgrading their previous generation flashes.

Why do I need an Accessory flash?

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Before we dive deeper into the upgraded features of the 430EX III-RT, you may be wondering if an external flash an important investment (and that would be a fair question). Few aspects of an image are as important as the lighting – arguably being second only to the subject and perhaps the composition. Good lighting overcomes so many other issues. With one or many 430EX III-RT flashes available for use, you can take control of the lighting. In doing so, this device (singularly or in multiples) has the power to completely transform the quality of your images. Here is an example:

Benefits of Flash

Flash can bring your images to life. The uses for this device are truly only limited by your imagination. And the results of using the Canon Speedlite 430EX III-RT Flash are potentially incredible.

As with all flashes, the 430EX III-RT is designed to add light to your scene. The amount of light added can range from a little to all of the light captured in the exposure. Use flash when there is not enough light or when there is none at all.

When a scene is already well-lit, add light from a flash to fill in harsh shadows. Did you ever shoot in a venue with direct downward lighting? Downward lighting creates raccoon eyes on your subjects – eyebrows shade the most photographically important part of your human subjects. Small and/or distant light sources also create harsh subject lighting. A flash can greatly improve your subject lighting in these cases.

The answer to the why do I need an accessory flash question may be obvious to owners of camera bodies without a built-in flash, but not so clear to those using bodies with a built-in flash. The built-in flash is great for fill (set your exposure for the ambient light, then dial in -1 to -2 EV FEC/Flash Exposure Compensation). The built-in flash will add light to the shadows and add catchlights (sparkles) to the subject's eyes – at short distances. The problem is that the range of the built-in flash is very short and the benefit of that flash is minimal in terms of overall image quality because it lacks an important feature – the ability to tilt and swivel. I'll come back to this point soon.

A flash can also improve the spectrum quality of the light reaching a scene. Not all light is created equal and some light is quite lacking in regards to its spectrum profile. The color quality coming from accessory flashes are optimized for photographical purposes and can overcome the color deficiencies found in ambient light sources when used as the full lighting for a scene. When including ambient light in the exposure, the flash will need to be gelled to match the color of that ambient light so that white balance can correctly be obtained.

A huge benefit of an accessory flash is being able to change the size and shape profile of the light reaching your subject. Using the tilt and swivel feature of the better flash models, light can be bounced from an appropriately-colored reflective surface. The color of that surface ideally will be light (dark colors absorb more light) and neutral enough that a strong color cast is not introduced into your image. A wall or reflector is commonly used for on-camera bounced flash.

If used off-camera, the flash output bouncing off of a white umbrella can provide simple but excellent soft lighting for your subjects. An off-camera flash can also be fired through a softbox, shoot-through umbrella, snoot, gobo, Light Blaster or diffuser. The bounce and diffusion options can result in a larger light source relative to the size of the subject for a generally much-preferred soft look to the lighting. Light fall-off across your image can also be controlled by varying the distance between your flash and your subject.

Let's take a look at an example that I created for the review of this flash's predecessor, the Speedlite 430EX II.

Built-in, On-Camera, Bounce and Off-Camera Flash Portrait Comparison

A Canon EOS 50D with a Canon EF 85mm f/1.8 USM Lens was tripod-mounted in vertical orientation (flash on camera left) for these comparison portraits. Yes, my beautiful model moves a bit between each comparison shot – she thought she needed a sip of tea during each flash change. The model is sitting on a stool in a simulated corner of two white walls (the wall to camera right is actually a very large reflector). A single flash is the only light used for each of these shots.

At even this relatively short distance, the 50D's built-in flash required ISO 200 and full power plus .25 stops added in post processing to reach this f/8 exposure brightness. The old featureless fixed head Speedlite 220EX had enough power at ISO 100 to reach the similar exposure.

Aside from power, the shoe-mounted flashes aimed directly at the subject do not offer much (if any) image quality improvement over the built-in flash. As the flash height increases on the hot shoe, the shadows lengthen – which is not a benefit aside from sometimes reducing the red-eye effect.

Interesting is that the shadow from the 430EX II is darker than the shadow from the built-in and 220EX flashes. The 430EX II's auto-zoom feature would have directed more light onto the subject - and less would have bounced off of the side wall to fill the shadows. Of course, I could have manually chosen a wider angle flash head setting on the 430EX II, but the cup of tea was empty by then. The 430EX III-RT, with its zoom head, would have delivered a result very similar to the 430EX II.

Adding a rotatable/flip-able flash bracket for the shoe-mounted flashes would have improved the quality of the direct flash for this vertically oriented portrait simply by sending the shadows downward.

All of the direct-flash images would appear nice compared to a flashless capture in this scenario (the subject was in very low light). Nice, that is, as long as you had not seen the bounced flash examples. When the flash is close to the axis of the lens, the light appears unnatural. The reason for this is because we rarely view the world with a bright light emanating from our foreheads (spelunkers are an exception to this rule).

Start bouncing the flash and everything changes. The source of the light becomes the object the light is bounced from. The reflective surface is typically something very large – and white in color is usually preferred. In the bounce example above, the flash was aimed into a white reflector held up to the back of camera left (the edge of a wall and ceiling often works well). The large size of the light source delivers a softer light, wrapping around the subject. The harsh shadows below the jaw line (right side in examples above) and on the background are greatly softened.

With the 430EX II doing the bouncing, ISO 400 was needed to achieve the proper exposure in this portrait. As the 430EX III-RT shares the same Guide Number (power rating) as its predecessor, this example should give you a good idea of what kind of camera settings you'll need when shooting in similar circumstances. One benefit of the 430EX III-RT is that it gains extra degrees of rotation compared to the 430EX II as the 430EX III-RT allows you to rotate the head to 60, 75, 90, 120, and 150° positions in both clockwise and counterclockwise rotations, with the 180° rotation available when turning clockwise. In the specific example above (which is often be encountered in the field), I needed the 430EX II to rotate into its dead rotation zone for optimal positioning. If I had been using the 430EX III-RT, the flash would be directed upward over my left shoulder, but I settled for rotated 180° back and tilted one click short of 90° for this example.

I'll pay a lot more attention to off camera flash use later, but I think you'll agree that the umbrella example above is the winner in this competition. A shoot-through diffuser is another optimal light modifier. Shoot-through diffusers include things such as softboxes, umbrellas, commercial diffusers, bed sheets and even transparent shower curtains.

Accessory flashes allow the use of a great abundance of direct-attached light modifiers. These modifiers range from complete gimmick to must-have in their usefulness. To be used for direct flash applications, a modifier must be very significantly larger than the flash head and sufficient internal diffusion must be incorporated to allow the flash to adequately and evenly light the entire front surface area of the modifier.

There is a lot more flexibility in size when some or all of the modifier's light will be bounced. One of my favorites is the Sto-Fen Omni-Bounce diffuser. This small, rugged, inexpensive accessory creates a bare-bulb effects that sends light in all directions. You end up with a combination of direct and bounced light on your scene. Of course, that the 430EX III-RT comes with its own diffuser (Bounce Adapter SBA-E2) means that accessory is no longer needed.

Note that any flash accessory counting on bounced light is only going to be effective when a reflective surface (wall, ceiling, etc.) is present. You are simply wasting battery life if using these devices on an open beach, in an open field, in a large arena, etc. While devices like these were sometimes used to reduce flash output long ago, modern flashes are capable of reducing their output to low levels without this help.

Providing a focus assist light is another advantage that flashes provide. While built-in, low-end and compact flashes can help with focus acquisition in low light, they use a series of very distracting quick flashes to do this. The higher end flashes including the 600EX-RT project a much less intrusive red grid pattern when focus help is needed. While the 430EX III-RT covers only the center AF point with it's AF assist light, it covers other AF points using the quick flash method.

Eliminating motion-blurred images is another challenge that flash can help you overcome. Stopping fast action can be challenging under all but under the brightest lights. And holding a camera still enough to capture sharp, motion-blur-free images can also be challenging. Because the light output from a flash happens with such short duration, a flash is able to freeze even very fast motion, making sharp photos much more attainable (if correctly focused of course).

A very significant percentage of photographers find at least one accessory flash to be an important part of their kit for one or more of the reasons listed above.

Canon Speedlite 430EX III-RT On Camera


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Power is one of the features you are looking for in a flash. By power, I am talking about how much light the flash can generate. Manufacturers rate their flashes for power output using the "Guide Number" spec, indicating the max distance a flash can light a subject.

GN = distance × f-number.

Unfortunately, this spec is difficult to use for comparative purposes. The better flashes available today have the ability to focus their beam of light, allowing a higher percentage of the light output to cover only the angle of view of the lens focal length being used. Or, more light can be focused in the center of the frame to create a vignette effect. Manufacturers typically take advantage of the light-focusing capability of their flashes when assigning the GN spec. If the flashes being compared do not have the same zooming capabilities, one flash gains an advantage.

The 430EX III-RT features a maximum zoom of 105mm with a guide number of 141.1' (43m) when used at the extent of its zoom range. Canon also provides the GN at the 430EX III-RT's widest angle (without the diffusion panel in use). That number is slightly more than half of the guide number at 105, or 72.2' (22m), at the 24mm position. An increase in power was not on Canon's upgrade priority list this go-around (the 430EX II's specs are identical).

If you find the 430EX III-RT's flash power to be lacking for any given situation, you can choose to increase your ISO, use a wider aperture (if possible) or shoot with a longer shutter speed (to increase the amount of ambient light captured in your exposure). Choose wisely, though, as all of the adjustments listed will have their own consequences such as increased noise, shallower depth-of-field or the possibility of motion blur. Thankfully, Canon made many other worthwhile upgrades that, in perspective, make the identical power rating seem like a small concession. If you need the ultimate in power from a single flash, the 600EX-RT will likely serve you better.

Otherwise, more flashes can easily give you more power and provide you with exponentially more options when it comes to lighting your subject. Each time you double the number of flashes in use (assuming they are the same model/power), you get twice as much light available for use on your scene. If you don't need twice as much light, the use of additional flashes will allow lower power settings to be used. Lower power settings deliver shorter bursts of light that freeze even faster action (think hummingbird photography) and recycle more quickly.

Canon Speedlite 430EX III-RT Features

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Powering on the 430EX III-RT, we immediately notice the addition of a Lock position, a design cue first seen on the 600EX-RT.

Canon Speedlite 430EX III-RT Back View

One | Two | Three | Four

Setting the flash to "Lock" will ensure that any settings you adjust on your flash will not be changed as the result of an accidental button press. The 430EX III-RT's On switch also has a new shape, similar to its big brother.

The 430EX III-RT's new dynamic LCD display is a noticeable and welcomed upgrade over its predecessor. The reduced number of buttons on the 430EX III-RT is another conspicuous change. The only buttons found on the flash (aside from the Set button in the middle of the Select Dial) are Sub Menu, Back and Test (or Wake) Flash. Instead of having four buttons just below the LCD as seen on the 430EX II, the Select Dial now allows direct access to many of the flash's features. As the Select Dial is easier to reach, its expanded functionality means that changing settings is both faster and easier.

A press of the Sub Menu button allows access to Personal and Custom Function settings and also allows you to clear the flash's settings to default.

The 430EX III-RT will automatically select the proper zoom focal length to match your lens and sensor size. If you need to go even wider than the flash's lowest available 24mm zoom setting, pull out and flip down the wide angle diffuser panel for a 14mm angle of view coverage. If you need to go wider still, attach the included diffuser.

Canon Speedlite 430EX III-RT Diffuser

In addition to the pull-out, flip-down diffuser, the 430EX III-RT has a catchlight panel. When using bounce flash, pull out the white panel to create a white catchlight reflection in your subject's eye.

Canon Speedlite 430EX III-RT Catchlight Panel

The catchlight panel is a new feature (the 430EX and 430EX II do not have it), and it can be a useful tool.

The Canon Speedlite 430EX III-RT Flash's available modes are ETTL, Manual and Group. Use the default ETTL mode to let the camera automatically determine the amount of light your subject/scene needs. Here is how the Canon Camera Museum describes ETTL Mode:

The "E-TTL / E-TTL II autoflash system [snip] was developed to meet the demands of the digital camera era. This system fires a weak pre-flash just before the main flash, measures the flash intensity necessary to properly illuminate the subject, and then fires the main flash (this sequence takes place in an instant). The E-TTL II autoflash system provides even more precise and stable flashes by utilizing the lens-to-subject distance. The system's algorithm is actually contained in the camera, so the system can be improved with each new model development."

Basically, in E-TTL mode, the camera automatically takes care of the flash power output. You simply install the flash on the camera and power it on. The camera does everything else.

The camera's mode setting is also important in determining the flash exposure in ETTL mode. I typically use Av mode when using flash for fill and use the camera's M (Manual) mode for flash-as-main-light photography. In the latter case, the camera determines how much flash is needed for proper image brightness at the aperture, shutter and ISO settings I choose. FEC (Flash Exposure Compensation) is used to make any adjustments needed.

If you want to take full control of the amount of light the flash is providing, use the flash's M (Manual) mode (highly recommended in some scenarios). An upgraded feature of the 430EX III-RT is that manual flash output from 1/128 power to full 1/1 output can be selected (in 1/3-stop increments). The 430EX II's lowest setting was 1/64 power.

Group mode is available with wireless flash, permitting a different flash mode to be selected for each firing group.

As Canon's mid-range flash, the 430EX III-RT gets a feature set that is adequate for most users' needs. Tell the flash to increase or decrease its output by using FEC (Flash Exposure Compensation). As usual, HS Sync (High Speed Sync) mode is available. Though a flash does not offer as much power in this mode, the camera's fastest x-sync shutter speed can far be exceeded.

All flashes default to first curtain sync – the flash fires just as the shutter opens. If the exposure being used is long enough for subject motion blur to become part of the final image, this will mean that your subject will have moved after the flash’s light illuminates them. The result is blurred streaks following the initial flash. In this case, it is best to use 2nd curtain sync. In 2nd curtain sync, the flash fires just before your shutter closes, causing the blurred motion streaks to appear behind the subject, resulting in a much more pleasing look.

Note that Flash Exposure Bracketing (FEB) and stroboscopic (MULTI) flash are not natively available but are supported when the 430EX III-RT is acting as a slave flash with a master flash that supports those features (i.e., the 600EX-RT).

While the 430EX II had Custom Functions, setting them and determining what settings were already in use was challenging due to the cryptic LCD information. The best method for deciphering the 430EX II's custom functions was to have the owner's manual readily available for reference. With the 430EX III-RT's new LCD, no longer is an owner's manual or cheat sheet required to set CFs along with the new PFs (Personal Functions) found on the 430EX III-RT – usually. You might need to read initially to understand all of the symbols being used.

Here is the list of the 18 Custom Functions found in the Canon Speedlite 430EX III-RT Flash:

C.Fn-00: Distance indicator display (ft, m)
C.Fn-01: Auto power off (On, Off)
C.Fn-02: Modeling flash (3 button options, off)
C.Fn-08: AF-assist beam firing (On, Off)
C.Fn-10: Slave auto power off timer (60 min, 10 min)
C.Fn-11: Slave auto power off cancel (8 hr, 1 hr)
C.Fn-13: Flash exposure metering setting (Speedlite button and dial, Speedlite dial only)
C.Fn-21: Light distribution (Standard, Guide Number Priority, Even Coverage)
C.Fn-22: LCD panel illumination (12 sec., Off, On)
C.Fn-23: Slave flash battery check (AF Assist Beam Blink On, Off)

The list of new 430EX III-RT Personal Functions are:

P.Fn-01: LCD panel display contrast (5 levels)
P.Fn-02: LCD panel illumination color: Normal shooting (Green, Orange)
P.Fn-03: LCD panel illumination color: Master (Green, Orange)
P.Fn-04: LCD panel illumination color: Slave (Green, Orange)
P.Fn-05: AF-assist beam emission method
P.Fn-06: Quick flash
P.Fn-07: Flash firing during linked shooting (Off, On)
P.Fn-08: Dial setting changes

C.Fn-21, Light distribution, is a feature that was initially introduced int the 600EX-RT and worth a brief explanation. When Auto Zoom is selected, the evenness of light across the frame can be adjusted using via flash head's zoom capability. Standard Coverage is what we are used to. A modest darkening toward the edges of the frame may be seen when this mode is used.

The new modes are Guide number priority and Even coverage. Even coverage aims to provide very even light across the entire frame. Guide number priority will place more light in the center of the frame with the periphery going darker. Use this mode to create a vignette effect, drawing focus toward the center of the frame, and/or to maximize the reach of your flash.

Canon has been including a flash menu in EOS digital cameras since 2007. Many of the more-advanced flash features (HS Sync, FEC, etc.) are now available on even Canon's lowest-end flashes when using cameras with flash menus included. If your EOS DSLR does not provide a flash menu or if you still prefer to change your flash settings directly on the flash, the 430EX III-RT has what you need. Note that the 1D X, 5D Mark III or later than 2012-introduced DSLRs support the full 430EX III-RT feature set (including RF wireless control). Not sure what year your DSLR introduced? Find that piece of information near the bottom of the camera specifications page.


Canon Speedlite 430EX III-RT Flash Wireless Capabilities

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As already mentioned, the Canon Speedlite 430EX III-RT Flash has wireless remote capabilities. Getting your flash off camera opens a world of creative opportunities to explore. As with previous generation flashes, the 430EX III-RT can also be controlled by a Speedlite or Speedlite Transmitter with master capabilities for a very small/light/portable/flexible lighting system. The portion of the 430EX III-RT's Select Dial dedicated to Wireless/Linked Shooting allows for quick and logical selection of wireless modes.

But the really big news is that the 430EX III-RT, like the 600EX-RT, has two additional wireless modes – radio frequency master and slave modes. For the first time ever in a 400-series Speedlite flash, the 430EX III-RT can control another Speedlite with remote slave capabilities (radio mode only).

With radio remote control, no longer is line-of-sight and a specific angle-of-view required to control remote slave flashes. I have long used Canon's optical wireless system and could usually make it work fine. Non-line-of-site optical wireless sometimes works in limited instances if the light bounces off objects in the room sufficiently to communicate with the remote flash(es), but there were situations where this option would not work (through walls, sometimes in very bright sunlight). Other situations required adjustment of light modifier setup to make the slave flash unit's receiver able to see the optical communications (if possible).

No longer do obstacles matter and remote flashes can be up to twice as far away indoors and three times the rated distance outdoors (98.4'/30m). The 430EX III-RT is being used via radio remote control from an out of site background location in the self-portrait shown above (learn more about this complicated capture here: 12mm Environmental Portrait and The Making of My First Selfie).

Via 2.4 GHz RF, the 430EX III-RT is able to control flash output for up to 5 groups (A, B, C, D & E) of up to 15 compatibles flashes communicating in one of 15 channels (default is Auto select) using one of up to 10,000 IDs (default is 0000) from up to 98.4 feet (30m) away.

The color of the link light (above and left of the LCD on back of flash) indicates the ability to communicate with the other flashes as follows:

Green/Lit: Transmission OK
Orange: Flash has sub-master status (this master unit was powered on after another master unit)
Red/Lit: Flash is not communicating with another unit
Red/Blinking: Too many units or other error

To insure interference-free communications, the 430EX III-RT has the ability to automatically scan its 15 channels and automatically select the best available. Interesting is that the 430EX III-RT, while manually set to a specific channel number, can produce a chart of the results of its scan. You can utilize this information to manually select the optimal channel for your venue.

With a 2012-or-later Canon EOS DSLR, a Flash Quick Control screen is available for fast, easy setting changes – and for fast verification of the current settings. The following image shows the 5D Mark III's flash function settings (with a 600EX RT mounted).

Canon Speedlite 600EX-RT Flash on Canon EOS 5D Mark III

My experience with the 600EX-RT and ST-E3-RT Remote Transmitter's radio wireless flash has been exceptional over the 3+ years it has been available. This is the system we use daily in the lab with hundreds of thousands of flash triggers initiated. That the 430EX III-RT lowers the entry cost of this high-performing system is very positive.

Canon's optical wireless remote flash capabilities are unsurprisingly still supported. The optical wireless flash control is being featured in many current Canon EOS DSLR cameras and remains the most-widely-used Canon remote flash technology. While RF and optical wireless modes cannot be used simultaneously, the 430EX III-RT has full backward compatibility with Canon's optical wireless system.

The 430EX III-RT is able to optically be controlled in ratios up to 3 groups (A/B/C) with an unlimited number of slave units supported. The latter is an advantage over the RF system, but ... the percentage of photographers needing to control more than 15 slave units is likely very small. The transmission range for optical wireless communication is (periphery-center) 39.4'-49.2' (12m-15m) indoors and 26.2'-32.8' (8m-10m) outdoors. The extents of periphery optical wireless reception are +-40 degrees horizontally and +-30 degrees vertically. Four slave channel IDs are available to avoid conflicts with other photographers.

Optical wireless compatible Canon Speedlite slave units can include, as of review time, the 600EX-RT, 580EX II, 580EX, 550EX, 430EX III-RT, 430EX II, 430EX, 320EX and 270EX II. Check the flash specifications tool for more recently released flashes.

For RF wireless operation, the master flash output can be disabled. If disabling the master flash output, the Canon Speedlite Transmitter ST-E3-RT (RF wireless only) may be preferred for its significantly smaller size and weight. Note that even when disabled, the master flash may fire a preflash (making it appear to be enabled), but will not contribute to the exposure. FEC, FEB, FE-Lock and HS Sync are available in wireless modes, but lacking is second curtain sync. Second curtain sync is unfortunately limited to a camera-attached flash.

The Canon Speedlite wireless flash system is very easy to use. Simply open the boxes, insert batteries, power the units on, press the wireless button (left arrow of the cross keys) and rotate the dial to select to master or slave mode and press the set button to confirm the setup. RF wireless setup is now complete. Everything will work.

As with the 600EX-RT, you can save the 430EX III-RT's wireless settings to memory for recall the next time they are needed – such as the next time you are shooting at the same venue. Want to reset a flash back to its default settings to quickly clear a complicated setup? Simply press the Sub Menu button, select the "Set. Clear" option and press the Sel/Set button to confirm.

Remote Release and Linked Shooting

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Not only can the Canon Speedlite 430EX III-RT control and be controlled by other Canon Speedlites and Speedlite Transmitters, this flash can control other EOS DSLR cameras.

Via its remote shutter release capability, a slave 430EX III-RT (or 600EX-RT / ST-E3-RT) can wirelessly instruct a single camera, with another RF-capable flash or flash transmitter mounted, to fire in single shot mode. The max range for this function is the same as the other RF wireless features – up to 98.4 feet (30m) away. The EOS 1D X, 5D Mark III and post-2012-released EOS DSLRs will be triggered directly through the flash hot shoe. Earlier camera models require the optional Canon SR-N3 Release Cable and a 600EX-RT or ST-E3-RT Transmitter to function in this way. The SR-N3 cable requires an N3-type remote release port which leaves some lower end camera models (including the Rebel/***D/****D series with E3-type ports) unsupported.

The flash or transmitter on the triggered camera can be instructed to fire or remain off for the exposure and can also control other slave flashes (via RF only). The triggering device is not required to be camera mounted. The remote release is triggered by selecting the slave's REL menu option using the Select Dial. It might appear strange to be carrying just a 430EX III-RT around, so the smaller and lighter ST-E3-RT may be more ideal for this task.

Using the Canon Speedlite 430EX III-RT's Linked Shooting feature, you really can be in up to 16 places at once. A 430EX III-RT (or 600EX-RT / ST-E3-RT) mounted on a camera is able to remotely trigger up to 15 other remote cameras located within the max RF operating range.

When I first learned about the Linked Shooting capabilities at the time the 600EX-RT was announced, my first thought was to setup a bullet-time-style shoot. Bullet time videos generally utilize a very large bank of cameras, a great deal of wiring and computer triggering technology. A subject in motion is simultaneously captured from many angles using the still cameras. The still images are then incorporated into a video that pans around the frozen-in-time subject.

Wireless triggering technology would eliminate the large wiring and triggering issues involved in such a shoot, but my limited number of fully compatible cameras (3) was going to make my shoot more of a proof-of-concept. What I learned is that there is a very short time lag from the first camera firing until the other cameras fire. This is not surprising, but if the slave cameras are not the same model, there may be a difference in their triggering lag time. My 1D X would trigger slightly faster than my 5D III, but multiple 5D III bodies would fire simultaneously. While more testing is warranted, the concept has potential. For other remote triggering needs, this system can work very well.

To enter Linked Shooting mode, press the left side of the dial and rotate the dial to select "Linked Shot" and press the Set button. A checkmark next to "Linked Shot" indicates that Linked Shooting is active. Another turn of the Select Dial (and press of the Set button) will allow you to specify whether the flash is a master or slave unit. The Linked Shot Master flash triggers the shutter release on the Linked Shot Slave remote cameras. Note that in Linked Shooting, flash information is not communicated to the slave units.

Linked Shooting differs from Remote Release in that the remote shutter activation can be triggered from the master flash camera's shutter release (the REL button also works). Again, Linked Shooting can remotely activate up to 15 cameras whereas Remote Release will activate only one camera. These features are not available for optical wireless communications.

Canon Speedlite Flashes

Canon Speedlite 430EX III-RT Flash Specifications

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Below is a table comparing the size and weight of some current Canon Speedlites and Speedlite Transmitters.

Canon Speedlite 600EX-RT Flash15.0 oz (425g)3.1 x 5.6 x 4.9"(80 x 143 x 125mm)
Canon Speedlite 580EX II Flash13.2 oz (375g)3.0 x 5.3 x 4.5"(76 x 134 x 114mm)
Canon Speedlite 430EX III-RT Flash10.4 oz (295g)2.8 x 4.5 x 3.9"(71 x 114 x 98mm)
Canon Speedlite 430EX II Flash11.6 oz (330g)2.8 x 4.8 x 4.0"(72 x 122 x 101mm)
Canon Speedlite 320EX Flash9.7 oz (275g)2.8 x 4.5 x 3.1"(70 x 115 x 78mm)
Canon Speedlite 90EX Flash1.8 oz (50g)1.7 x 2.0 x 2.6"(44 x 52 x 65mm)
Canon Speedlite Transmitter ST-E3-RT3.9 oz (110g)2.7 x 2.4 x 3.1"(67 x 62 x 77mm)
Canon Speedlite Transmitter ST-E23.5 oz (100g)2.4 x 2.0 x 3.1"(62 x 51 x 80mm)

For many more comparisons, check out the complete Canon Speedlite 430EX III-RT Flash Specifications using the site's Flash Spec tool.

The 600EX-RT is Canon's current top-of-the-line flash (left-most in previous comparison image). As such, its size/weight/price reflects its position. As indicated earlier, the 430EX III-RT occupies the role of Canon's mid-level flash with a price and power to match. However, the 430EX III-RT's range of features – including master functionality – places it much closer to Canon's top-tier flash compared to its predecessor.

While you may think it is strange that I included the 90EX in the above list as this is currently Canon's least expensive flash model. I included it for two reasons. First, I included it for perspective as it is tiny and light. The second and more important reason for including the 90EX is that it has remote flash master capabilities, just like the 430EX III-RT. This little flash can control the 430EX III-RT and other optical-slave-capable models, making it compete strongly against the significantly more expensive ST-E2 remote transmitter. Unfortunately, at 430EX III-RT review time, the 90EX does not appear to be in good supply.

Also small and light are the Speedlite Transmitters. I much prefer having one of these on my hot shoe if not using flash on the camera while shooting with wireless flash.

It is not as small and light, but the Canon Speedlite 430EX III-RT Flash is a solidly and thoughtfully built product with a style much like the 600EX-RT (and that's a good thing).

Canon Speedlite 430EX III-RT Flash Product Images

Starting at the front, we see the flash head. In addition to being the all-important light source, the flash head is responsible for optical wireless master communications. The red plastic piece covers the AF-assist beam emitter and the optical wireless receiver. The pull-out diffusion panel can be seen tucked into its slot just below the small white catchlight reflector.

Moving to the right, the battery door dominates this side of the flash. The 430EX III-RT is powered by 4 AA batteries. I strongly recommend using NiMH rechargeable batteries that maintain their charge when on the shelf. I rely on Sanyo Eneloop and Sony Cycle Energy batteries. Note that Canon strongly recommends avoiding AA Lithium batteries because, in rare cases, they may become extremely hot during use.

The 430EX III-RT silently recycles in 0.1 - 3.5 sec. and is rated for 180-1200 shots on a new set of alkaline batteries. The recycle figures range from very impressive to moderately slow. In real use, I find the flash to charge very quickly most of the time, but the amount of flash power being used will determine the recycle time you should expect for any specific situation (assuming adequately charged batteries). Battery life seems quite adequate to me in real use.

Also on the right side, the bounce head release button is seen. As already noted, the 430EX III-RT's head is more adjustable than its predecessor (a very welcomed feature), though still shy of the 600EX-RT's 180° in both directions and missing the slight downward tilt this flash enables. Here is an illustration of the available adjustment range:

Canon Speedlite 430EX III-RT Flash Head Positions

Simply press the release button and twist the head in the direction you want light sent to. The rubber on the sides of the head provide a good grip surface for holding the flash, for making head angle adjustments and for holding head-mounted third party accessories.

New for the 430EX-series of flashes is a color (green or orange) LCD backlight that is programmable via Personal Functions (P.Fn-02 – P.Fn-04). For example, set your flash to show orange when in slave mode and green when in master mode (note that some with various types of color blindness may have difficulty distingusing the colors). For most, the different LCD colors make the flash's mode easily distinguishable.

The LCD backlight will also turn red and then flash red as thermal overload levels are approached.

Note that the 430EX III-RT does not feature the same hot shoe seal as found on the 600EX-RT and weather sealing is not promoted as a feature of this flash. Care should be taken to avoid rain/moisture, especially in the hot shoe area.

Moving to the left side of the flash, we can see that the 430EX III-RT looks conspicuously bare. The remote release terminal, external power supply socket, PC terminal and flash mounting bracket features of the 600EX-RT are absent in Canon's mid-level flash.

Seen near the top of the flash vertical orientation images are 2 small, recessed ports in the front and three small, raised dots in the back. These are the attachment points and sensors for the new, previously mentioned Bounce Adapter SBA-E2 and tungsten (full cut orange) Color Filter SCF-E2. Using gel filters is a common need for flash photography. These are used to match the flash output color to the ambient light (tungsten in this case), allowing the entire scene to be evenly white balanced. Or, use filters to creatively add a splash of color to your image, a warming effect in this case.

Canon Speedlite 430EX III-RT Color Filter SCF-E2

The 430EX III-RT comes in a nice padded nylon case with a belt loop on the back and a D-loop on the side, allowing the case to be attached to another case or a small case attached to the flash case (such as the small storage pouch included for the diffuser/filter).

Accessories the Canon Speedlite 430EX III-RT Flash

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There are many, many direct-flash-head-attached accessories available for improving direct flash image quality. I've tried many and like very few. Most simply do not create a large enough lighting surface to significantly soften the light from direct flash – not enough to be worth the inconvenience of using them or the additional battery consumption they cause. The ones I've tried with great potential – ones that have a large enough light surface – are mounted too close to the flash head to make use of that surface without an intermediary diffuser. Rogue FlashBenders are one of the exceptions.

Accessories that facilitate bounce or bounce plus forward direct light have a much higher potential than the direct flash devices – as long as a bounce surface is available. Be wary of the overly complex designs.

The list of available off camera flash accessories that significantly improve flash lighting are huge. Umbrellas, softboxes, reflectors and diffusers are among the best and most common flash lighting accessories.

Canon Speedlite 430EX II, 430EX III-RT and 600EX RT Flash Comparison

Alternatives to the Canon Speedlite 430EX III-RT Flash

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The 430EX III-RT enters the market in the second-from-the-top position in Canon's Speedlite lineup. The best Canon flash available is the 600EX-RT as seen on the right side in the above comparison image. Here are some of the 600X-RT's advantages over the 430EX III-RT:

  • More powerful: Guide Number 196.9' (60m) vs. 141' (43m)
  • Max zoom of 200mm vs 105mm
  • Weather-sealed design and self-cleaning foot design
  • 18 custom functions and 7 personal functions vs. 10 and 8
  • Auto External and Manual External Flash Metering vs. none
  • Multi Mode vs. none
  • Remote release terminal vs. hot shoe remote release only
  • External power supply socket vs. none
  • PC terminal vs. none
  • Flash bracket mount vs. none
  • Audible (Beep) Indicator vs. none

Size, weight and price are the 600's disadvantages. If you are serious about your flash photography, the 600EX-RT is the right choice.

The Canon Speedlite 430EX II Flash is the next model down from the 430EX III-RT. Down in capabilities and price (though it is modestly larger in size). Review the list of 430EX III-RT advantages over the 430EX II at the top of this page. Most will find the III's advantages to be worth the price premium over the II.

I expect the 430EX II to be phased out at some point and that will leave the Canon Speedlite 320EX Flash as the next model down. The difference in functionality between the 430EX III-RT and 320EX is large. Check out the Canon Speedlite 430EX III-RT vs. 320EX comparison for some of the details.

If you have viewed the Canon Speedlite 430EX III-RT manual, you may have noticed a Canon "Speedlite 430EX III" listed on the cover. While I have not seen the sans-RF flash for sale here in the USA, you should be aware that this flash could exist in some locales. Make sure that you get the "-RF" version if you have any interest in the radio wireless technology. But, if you do not need the radio remote functionality, the 430EX III could be a reasonable alternative.


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The 430EX III-RT owner's manual is 108 pages in length and provides a good indication of the breadth of this Speedlite's feature set. It may be a bit dry, but reading the manual in its entirety is a good idea – you can find a link to the manual at the top of this review. Obviously, I'm only skimming the surface of the capabilities of this flash to keep this review concise. What you need to know first is why you need a flash and second, if the 430EX III-RT's capabilities make it the right model for you. Hopefully this review helped you answer that question.

After spending a good amount of time using the 430EX III-RT, I don't have any reservations in recommending it (as long as the 600EX-RT would not serve you even better). This flash has performed very reliably and gave me the light I was expecting, including on my most recent photo trip to North and Middle Caicos. At the beginning of this review, I showed a with and without flash comparison example featuring Rick on drums. I was exploring, looking to capture the culture of the islands and I found it at Miss B's Fish Fry. The lead singer, "Lovey", was also looking great:

Benefits of Flash

The duo was playing just inside the shade from an outdoor patio roof. Looking inward, they were not going to be photographed without the harsh sunlit background in the frame. Without a flash with me, silhouettes or pure white backgrounds were what I was going to get. Fortunately, I had the rather compact and easy to travel with, yet still powerful, 430EX III-RT with me. By sitting directly on the floor and using a telephoto lens (the Canon EF 100-400mm f/4.5-5.6L IS II), I was able to get properly exposed backgrounds that were at least reasonably pleasing to the compositions.

I put the camera in manual exposure mode, adjusted my settings to properly expose the background and then adjusted FEC (Flash Exposure Compensation) for the desired subject brightness relative to the background. Note that, for those shooting with the ETTR (Expose to the Right) concept to optimize image quality, the subject and background must be similarly exposed. Potentially, both will be over-exposed. FEC for the drummer image was -2/3 and +1/3 for the singer.

Another situation where the 430EX III-RT was useful:

Canon Speedlite 430EX III-RT Provides Fill Light for Beach Scene from Porch

The view from this porch was beautiful, but I wanted the porch itself to not become a silhouette. I also did not want it to become bright enough to be distracting. In this case, bracketing determined that a +1/3 FEC setting seemed just right.

As mentioned earlier, the 430EX III-RT has been useful around the studio as well, including taking a role in my first (and still only) selfie.

Canon's optical wireless remote technology served me well for a very long time (and this technology remains available in the 430EX III-RT), but the benefits of radio triggering meant that I have completely retired the older technology from my use. The radio wireless control along with other improvements make the 430EX III-RT a very solid upgrade from any flash below it. The 430EX III-RT will also make a great addition to a kit currently (or in the future) comprised of one or more 600EX-RTs.

If you are a professional or serious amateur photographer, choosing the 430EX III RT over the 600EX-RT involves some compromises, yet many will choose Canon's new mid-level flash because of its feature-set-to-price ratio. If you are buying your first serious accessory flash, this would be an excellent choice. If adding a flash to an existing system, the 430EX III-RT makes an excellent case for itself. Backward compatibility means that the new flash will play nicely with the other flashes in your kit and you will be preparing to take the next step with technology.

Adding master flash functionality into the 430EX III-RT has helped close the gap between Canon's top performing flash and the company's next available offering. The Canon Speedlite 430EX III-RT is reliable, well spec'd flash very worthy of its moderate price tag. Its feature set and performance make it a great flash for amateurs, advanced hobbyists and pros alike. The 430EX III-RT will surely prove a popular choice for photographers looking to add a flash to their kit.

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Canon Speedlite 430EX III-RT Flash
Canon Speedlite 430EX III-RT Flash
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