best master speedlite 430EX III-RT or ST-E3-RT

Canon’s radio wireless flash system has three devices that can control slave flashes; Speedlite Transmitter ST-E3-RT, Speedlite 430EX III-RT and Speedlite 600EX-RT. I have used the ST-E3-RT since it’s introduction, but can the Speedlite 430EX III-RT be a worthy alternative master?

When I use flash off-camera, I almost never use one of the lights on the camera hotshoe. Putting a light on the hotshoe means that it moves as I move the camera and changes the lighting on my subject from frame to frame. Since the introduction of the radio wireless system the Speedlite Transmitter ST-E3-RT has been my chosen on-camera controller. With the introduction of the Speedlite 430EX III-RT there might be an alternative option.

The best master Speedlite

Considering the features of both the Speedlite 430EX III-RT and ST-E3-RT there are a lot of similarities, including:

  • Control up to 15 radio slaves in up to five groups
  • Selectable flash modes as a radio master: E-TTL, Manual, Multi, Group
  • Group control: E-TTL, Manual, External Auto, Off
  • High Speed Sync: YES
  • Modelling light: YES
  • Linked shooting: YES
  • Remote shutter release from slave: YES


Speedlite Transmitter ST-E3-RT

best master Speedlite ST-E3-RT

In brief: The Speedlite ST-E3-RT is smaller, lighter, weather sealed, has the same control layout and capability as the Speedlite 600EX-RT

  • AF assist light: NO
  • Weather sealed: YES
  • Size: 67.4mm x 61.5mm x 77.4mm
  • Weight: 162g (with batteries*)
  • Powered by 2 x AA
  • Same button layout as Speedlite 600EX-RT
  • Trigger older cameras using SR-N3 release cable
  • Price £234 Amazon UK / $263 Amazon USA

best master Speedlite ST-E3-RT

Speedlite 430EX III-RT

best master Speedlite 430EX III-RT

In brief: The Speedlite 430EX III-RT has an AF assist light, and can flash if needed

  • Flash modes as a slave: E-TTL, Manual, Multi
  • AF assist light: YES
  • Weather sealed: NO
  • Size: 70.5mm x 113.8mm x 98.2mm
  • Weight: 399g (with batteries*)
  • Powered by 4 x AA
  • Different button layout than Speedlite 600EX-RT
  • Price £249 / $299 – press release prices

best master Speedlite 430EX III-RT

* Set of four AA Eneloop batteries weigh 104g

Which is the best master Speedlite for you?

Details are still thin on the ground for the Speedlite 430EX III-RT, at least until the manual becomes available. Once I find out more accurate information I’ll revisit this post.

UPDATE: 14th July, I’ve managed to get some clarifications from Canon about the exact capabilities of the Speedlite 430EX III-RT.

Prices at the moment look to be comparable, so in the main it will be a choice of smaller size, lighter weight, maximum control capability, weather sealing (ST-E3-RT) vs an AF assist light, and the option to use it as an on-camera light (430EX III-RT).

Buying your first Speedlite?

If you are just starting to build your radio wireless flash system or don’t yet have a Speedlite then the 430EX III-RT is a great first step. You may can use the built-in Speedlite master of your EOS 600D / 650D /  700D / 750D / 760D / 60D / 70D / 7D / 7D Mark II to control the 430EX III-RT as an optical slave. You’ll need to make the decision about buying an ST-E3-RT as your second device or another 430EX III-RT. I might be tempted by a second flash rather than an ST-E3-RT. The best thing is that if you buy the Speedlite 430EX III-RT as your first Speedlite it will now be usable with the radio system in the future as you buy other flashes.

Already have a single Speedlite 600EX-RT?

If you already have a Speedlite 600EX-RT but no trigger, the ST-E3-RT has the same button layout, is smaller and lighter and is fully weather sealed.

External Auto metering and stroboscopic modes are missing from the Speedlite 430EX III-RT, I do use External Auto metering with some of my groups of Speedlites at times. If the 430EX III-RT can’t control a group of Speedlite 600EX-RTs  in External Auto that would be a pain. In all honesty, multi / stroboscopic mode very rarely gets used in my work so I won’t miss it on the 430EX III-RT if it can’t do this as a master.

14-July: Stroboscopic modes are missing from the Speedlite 430EX III-RT unless it is a radio master or slave. However if the 430EX III-RT is a slave in a group set to Multi / Stroboscopic mode it can flash stroboscopically.

External Auto metered flash

What I’m still keen to find out is what happens when the ST-E3-RT is used as a master and a group of slaves with both 600EX-RTs and 430EX III-RTs is set to External Auto?

14-July: The Speedlite 430EX III-RT can in Group mode set a group to use External Auto mode. If the Speedlites in the group are Speedlite 600EX-RTs then the Ext A group will work as usual. Any Speedlite 430EX III-RTs in a group set to External Auto will not fire at all.

Already have several Speedlite 600EX-RT and an ST-E3-RT?

I think that as a backup the Speedlite 430EX III-RT makes sense, it can work as a backup to the ST-E3-RT in most cases and will also be a backup flash for the 600EX-RTs. You might be able to put the 430EX III-RT in tighter locations than a 600EX-RT.

Second curtain / rear curtain sync?

Lastly, and this could be the decider – I wonder if Canon managed to get second curtain sync to work over radio with the 430EX III-RT as a master?

14-July: No they haven’t added second curtain sync 🙁

Shipping date in Europe is September, same as USA 🙁



About the author

Full-time photo tutor and photographer. I love to share my knowledge and skills to make photos, videos and teach others. I write books and articles for photo magazines and I always have at least one Speedlite flash in my camera bag