
review: Canon ST-E3-RT Speedlite Transmitter and Canon 600EX-RT Speedlites
In my review of the Canon Speedlite 600EX-RT, I’ve already raved about the ease of use of the new speedlite – thanks to a menu system that you can follow without having to decipher it via a manual), but mostly because of the built-in radio control of the flash. This elevates the Canon 600EX-RT to a new level. As mentioned in my review, I really think this flashgun will change things in the photo industry. It’s huge.
I’ve only now been able to get hold of the ST-E3-RT Speedlite Transmitter (B&H), to use with the Canon 600EX-RT speedlites, and I am just as impressed.
The main advantages of this controller, is that you can change the flashes’ output directly from your camera. No need to run to and fro between your speedlights to change a flash’ output. And of course, The Big Thing about the new flash system, is the built-in radio control. You’re not limited by line-of-sight anymore, or compelled to buy radio slaves. It is obvious that Canon has done their homework on this puppy. While it is a complex flash system, the Canon ST-E3-RT isn’t a complicated device to use.
To test this system, I used three Canon 600EX-RT speedlites (B&H) and a ST-E3-RT Speedlite Transmitter (B&H) in a photo-shoot. As always, there’s a description of how I used this in the photo session … but more interestingly, a behind-the-scenes video clip of how the Canon 600EX-RT speedlites were set up for this photo shoot.
Canon ST-E3-RT features
1. Ease of use.
The ST-E3-RT controller has an LED which shows when a speedlite is connected to it. Beautiful. No guesswork.
You can control up to 5 groups of flashes with the latest Canon SLRs, or up to 3 groups with the previous generations of Canon SLRs (such as the 5D mark II). On paper, it looks impressive, but a simple listing of specs doesn’t quite do it justice. From the way the transmitter is angled towards the photographer to make the display easily readable, to the large LCD, it is all designed to make your life as a photographer much easier.
2. backwards compatibility
You can use the Canon 600EX-RT and Canon ST-E3-EX on any Canon D-SLR, although the one mode – Gr – is only available for the most recent Canon SLRs like the 5D mark III.
So, if you’re interested in what the new Canon flash system has to offer, you can use it already.
3. using the Canon ST-E3-RT
There are 4 main modes in which you use the controller:
ETTL – you can group your flashes as All; A:B or A:B C
Manual – you can similarly group your flashes as All; A:B or A:B C
Multi – for stroboscopic effect
Gr – this is the most interesting of modes – you can simultaneously set A or B or C up as either manual or TTL
The Gr mode is only accessible with the recent generation of Canon SLRs – the 5D mark III and the Canon 1D-X, or any future cameras.
What sets this mode apart, is that the Canon flashes are now controllable in the same way that the Nikon speedlights are – instead of ratios, you now control your speedlights in absolute values. Much more logical, in my opinion. You can have group A as TTL, and group B as manually controlled flashes … with their levels controlled by you, from the camera’s position.
In this photo session, I used the Manual mode, instead of Gr mode, since I was using the Canon 5D mark II.
There are 4 levels of menu, which offers you control over different aspects of your flash:
- Custom functions
- flash exposure bracketing
- flash exposure compensation (overall and for individual groups)
- high-speed flash sync
- ratios and groups
- channel & ID
And unlike the obscure menu of the Canon 580EX II, the menu system of the ST-E3-RT and 600EX-RT, are obvious. They tell you what you’re looking at. No need to delve into the menu every time you want to change a custom setting. Finally! Thank you, Canon!

using the new Canon flash system during a photo shoot
As mentioned earlier, to test out the Canon 600EX-RT (B&H) and ST-E3-RT Speedlite Transmitter (B&H), I met up with a model, Molly K, in Brooklyn. Molly has appeared a few times already in recent articles on the Tangents blog:
- off-camera flash in low light – choosing your shutter speed
- review: Impact Quikbox Softbox (24″ x 24″)
- what photo gear had a fundamental impact on your photography?
We started off in a well-known area of Brooklyn. This amazing graffiti is well-known in the area as a backdrop for photographers, especially wedding photographers.
I wanted to use 3 speedlights, all controlled by the ST-E3-RT:
A: the main light on our model,
diffused with my favorite Lastolite EZYBOX Softbox (24″x24″) (B&H)
B: the 2nd flash on the background to create a hot-spot behind her.
(I had to flag this with black foamie thing to ensure no direct flash fell on her from this.)
C: the 3rd flash directly behind her as a rim-light.
B and C were bare flashes, undiffused.
I used the three speedlights in Manual Mode, with the flashes set up as A:B C Since I was using a Canon 5D mark II, I couldn’t use the Gr mode, but had to use the Manual mode. Ultimately, in this case, the results are the same, since I didn’t have the need here to mix TTL flash and manual flash.
Here is the pull-back shot of the final set-up.
camera settings for the image at the top:
1/100 @ f7.1 @ 400 ISO … available light completely under-exposed
The behind-the-scenes video clip as I set every thing up, will explain more.
You can actually hear the thought-process.

For the one pull-back shot, I took a vertical photo, and saw this dramatic sky, and decided to use it for another set-up where we shot up the street.

My final summary, using the Canon 600EX-RT speedlites (B&H) and ST-E3-RT Speedlite Transmitter (B&H) during an actual shoot – well, color me impressed!
equipment used during this photo session
Canon 600EX-RT (B&H)
ST-E3-RT Speedlite Transmitter (B&H)
Canon CP-E4 battery pack (B&H)
Canon 24-105mm f/4L IS (B&H)
Canon 5D Mark II
Lastolite Hot Shoe EZYBOX Softbox Kit (24″x24″) (B&H)
Manfrotto 1051BAC - small (B&H); Manfrotto 1004BAC - tall (B&H)
Frio ColdShoe Mount (B&H)
black foamie thing
video clip shot with:
Nikon D4 camera (B&H); Nikon 24-70mm f2.8G ED AF-S (B&H)
photography books by Neil vN
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Fascinating as always! Love the inclusion of the video, brings it all home so much better than text alone. Thanks for the effort.
Comment by Chris D. — June 6, 2012 @ 6:17 pm
See You been busy Neil! Keep up the good work – cant wait to meet you and shoot together!
Great Video bye the way!
Keep Well!!!
Comment by Mike Greenslade — June 6, 2012 @ 6:23 pm
Neil,
How does the new Canon system compare to or differ from in terms of functionality from the Pocket Wizard AC3 AC5 combination? Would you care to comment please?
Comment by Mike — June 6, 2012 @ 7:04 pm
I wonder what Nikon’s response will be to Canon’s ST-E3-RT Speedlite Transmitter ? The “line of sight” & other problems of the Nikon CLS system made PocketWizard successful.
DSLR’s should have the wireless system built into the camera’s. I don’t like a camera to look like a christmas tree with all kinds of external gadgets which can be built into a camera, like GPS and Flash Radio transmitters. Here is an example of a patent for “Built-in Pocketwizard Transmitter for DSLRs”
http://flashraw.com/built-in-pocketwizard-flash-triggers-for-dslrs
Even cheap mobile phones have built in GPS’s (the technology is available), but a basic GPS for a camera cost a fortune.
How does the ST-E3-RT compare with the PocketWizard system?
Comment by MvH — June 6, 2012 @ 7:48 pm
Comment by Neil vN — June 6, 2012 @ 7:52 pm
Great review and images Neil.
Canon has definitely taken the lead on this and I hope Nikon answers soon. I use Radio Poppers to achieve the same results but I would be happier with less velcro…
Comment by Brian — June 6, 2012 @ 7:54 pm
hey Neil,
You dont have problems removing the 600EX flash off the Frio? takes me years to get them off. what’s your trick?
Comment by johnlo — June 6, 2012 @ 10:24 pm
Comment by Neil vN — June 6, 2012 @ 10:37 pm
So amI right that this new Canon system is basically Nikon’s system + radio + 2 more groups?
Comment by Ted — June 6, 2012 @ 10:47 pm
Comment by Neil vN — June 6, 2012 @ 11:06 pm
Great review. When I first purchased my three 600EX-RT units I was a little hesitant about them, since I’d heard they weren’t fully compatible with my 5D2 cameras. Allegedly the 600EX-RT units can’t use HSS when used in wireless trigger mode (ie, the reason I bought them in the first place!). Also, the manual says my max sync speed would be reduced to 1/100th. This was completely unacceptable so I made sure to test them out in the store before I bought them. No problems at all using HSS with the OCF units, nor was my max sync speed reduced. And, unlike the setup between my 580EXII units and my Pocket Wizard TT5 units, these new Canon 600EX-RT speedlights worked EVERY SINGLE TIME, whether they were on-camera or off-camera.
I didn’t buy the ST-E3 since there’s no focus-assist (similar to the drawback of the PW AC3 Zone Controller), while the 600EX-RT units themselves offer all the functionality of the ST-E3 and I can use one on-camera to achieve focus-assist in low light if I want. It’s also very easy to disable the on-camera unit from firing.
Comment by photomatte — June 6, 2012 @ 11:16 pm
Comment by Neil vN — June 7, 2012 @ 3:05 am
Photomatte, I’m glad you mentioned about HSS with the 5D II. I often wondered if it was possible as I would need this to work for me on my 5D II. You also answered my other concern in regards to AF-assist. Now I know to buy another flash instead of the transmitter. Glad I read the comments! And Neil, your reviews are what keep my camera bag top notch :-)
Comment by laura n. — June 7, 2012 @ 9:55 am
@Mike – in addition to the AC3 controller advantage, one other minor advantage to the pocketwizard ControlTL system is that it’s capable of rear-curtain sync (perhaps not a big deal to most), whereas the new Canon system cannot do rear-sync. I now have both systems and the Canon setup is certainly much easier to deal with in terms of less gear to carry, connect, fewer batteries to maintain, etc. And that green LINK confirmation light on each of the canon devices is a beautiful confirmation that the thing is going to fire.
Comment by Chris D. — June 7, 2012 @ 10:15 am
Great video using the Nikon D4. Thanks for providing us with beautiful clear crisp sounds. Many others do not produce the quality sound found in your videos.
I am almost ashamed to ask but knowing the answer helps me arrive at the AH-HA moment. I assume the camera was set on manual ( you mentioned the settings ) Can I correctly assume that the three flash groups were set to TTL ???
Comment by RON LEMISH — June 7, 2012 @ 6:54 pm
Comment by Neil vN — June 7, 2012 @ 7:01 pm
For those not wanting to trade-in their 580 EX IIs for 600EX-RTs and an ST-E3-EX, the Phottix System (whose interface Canon seems to have copied) works great.
Comment by dbltapp — June 7, 2012 @ 7:02 pm
Another great review. The only essential photography blog IMHO.
I was sitting on the fence about the 600s until I read your earlier review. I purchased two the next day. Loving them. A third will be on the way soon.
Comment by andrew — June 8, 2012 @ 6:10 am
I can’t let the Gang of Four reference go unchallenged. Entertainment wasn’t a bad debut, but I prefer The Clash, The Only Ones, The Sex Pistols, The Saints, The Birthday Party, The Dead Kennedys, or a couple of New York’s finest: The Ramones and The New York Dolls. Then there’s the Stooges….
Comment by andrew — June 8, 2012 @ 6:13 am
PLease don’t forget Stiff Little Fingers. b.t.w. great system works like a charm.
Comment by paul — June 9, 2012 @ 8:46 am
Good review and I’m glad Canon is going in this direction. I invite you to look at Phottix Odin triggers. Very similar functionality (including Gr for older camera + eTTL flash), HSS, and Odin LED looks very similar to 600EX-RT. And did I say that Odin is extremely easy to use?
Good seeing and assisting you at After Dark CLT. Love your blog.
Comment by Jim Pierson — June 9, 2012 @ 4:27 pm
Hi Neil
I always look forward to your monthly newsletters. Love to attend one of your seminars in NY but the bus service from here is not all the hot.
We have invested in a black foamie thing which we have found to be invaluable. Your description at the end of review of the New Flash and Transmitter listing the equipment you used, brought a smile to my face when I saw you listed the “black foamie thing”
regards
Derek
Comment by Derek Salter (NZ) — July 2, 2012 @ 4:16 pm
Hi everybody, i have a question:
last week i purchased a couple of 600ex and a st-e3-rt and i am very happy with them, especially for letting me say goodbye to Pocketwizard…
The only thing not clear to me: with the st-e3-rt mounted on the camera in E-TTL mode, if i change the flash exposure from the transmitter it does not seem to have any effect to the slave flashguns, or at least the values on the flash display remain the same.
When in manual mode instead every change made on the transmitter also correctly affects the flashes.
Am i missing something..?
Cheers,
Carlo.
Comment by Carlo — July 10, 2012 @ 3:34 pm
Sorry, i forgot to say that i am using a 5D Mark II…
Comment by Carlo — July 10, 2012 @ 3:37 pm
Comment by Neil vN — July 10, 2012 @ 3:41 pm
Hi Neil, no i am not in Gr Mode, just in simple, good old E-TTL. One flash slave A, the other one is slave B. The ST-E3 display says ETTL, and the “ALL” field is visible: when i dial on flash exposure compensation on the transmitter there’s no response on any of the flashes, although on the transmitter i can see that the values change. I made a few test shots against a grey background but the results were not helpful at all…
Thanks..
Comment by Carlo — July 10, 2012 @ 3:55 pm
Ehm, when i say ” there’s no response on any of the flashes” i mean that the exposure values scale does not change…
Comment by Carlo — July 10, 2012 @ 3:57 pm
Problem solved.. well it was not a problem actually, but this morning i test-shot a few pics at a model on a black background, the camera on a tripod with the transmitter and a single external 600 EX on a tripod too. The model was not moving and so the camera settings and lens zoom were the same all along the quick session. I just changed the FEC values from -3 to +3 shooting a single picture for every different step.
Everything worked out right, which means that the amount of flash burst did varied according to the different FEC values that i set on the ST-E3, although on the flash LCD screen the FEC value always remained at the neutral position.
After all i was just worried for this lack of communication between the ST-E3 and the flashes, and although the most important thing is that they DO communicate, it wouldn’t be a bad idea for Canon to mention this kind of behaviour somewhere on their user guides…
That’s all, now i go wasting some tenths of GigaBytes on this warm sunny day here in Sestri Levante…!
Cheers,
Carlo.
Comment by Carlo — July 11, 2012 @ 6:19 am
Hello Neil, I wonder if you did some testing on the shooting distance.?
very good your video, and I have his book released here in Brazil. Dedicated Flash, it changed my way of shooting, thanks.
Comment by Eric Cravo — August 7, 2012 @ 8:17 pm
Comment by Neil vN — August 8, 2012 @ 2:50 pm
Thanks for responding Neil, congratulations on your work and for his book, I’m always showing to friends who have problems with flash … big hug.
Eric Cravo.
Comment by Eric Cravo — August 8, 2012 @ 7:40 pm
a question posted with the Vimeo clip:
Neil, I am learning SO much from your blog and videos. Thank you! Quick question though – what power are you using on the flashes? After you zoomed the light on the wall, you had to go from f/5.6 to f/7.1 – could you have also reduced the power? Same thing for the softbox – you said it wasn’t recycling fast enough so you put in a battery pack. In the video it looks quite far from the model, could you have also moved it closer and reduced the power, or would that also affect the lighting pattern on her? Was this a specific choice that you made? Thanks again! Beautiful work, I’m getting so much inspiration from you.
Michael Johnson
See the video:
http://vimeo.com/43553260
Comment by Neil vN — November 11, 2012 @ 2:36 am
Comment by Neil vN — November 11, 2012 @ 2:38 am
Hi Neal,
Great reviews and great that you reply to all of these questions.
I did read that you say that the pw with ac3 is quicker to setup. But I wonder if the transmitter menu still works fast enough to switch channels on and off and change the intensity during a wedding ceremony
Comment by Roy — December 9, 2012 @ 4:29 am
Comment by Neil vN — December 10, 2012 @ 11:50 am
Hey god review
I just bught a 600ex and the st-e3 and it is a grait system. Now i godt the eos 6D and tryed it out words perfekt.
But i am trying the Collor filters, and can’t realt se what is going on, When I shout indoors with ambient light at about 2700K i put the collorfilter on the flash. On top off the camere it works fine, but with the off camera with the st-e3 it dosn’t. But if i set the whitebalance manualy there is no difference.
Comment by Jan — January 4, 2013 @ 6:50 pm
Great review Neil thank you. I have just switched over to Canon and your reviews and information on their flash range has been hugely useful to me.
Paul
Comment by Paul Donovan — February 7, 2013 @ 4:31 pm
Neil,
Thanks for a great review. I just purchased two 600′s and an ST-E3 from B&H through your website link to help support this fantastic Tangents blog. You’ve got the best photog website on the planet!
-Lew
Comment by Lew Tarnopol — February 20, 2013 @ 1:55 pm
hey is anyone try 600 ex rt +st-e3 with canon 6d ?
is the HSS work with 6d?
because i want to shoot in outdoor at the sunlight with over 1/2000ss
Comment by aldy — March 3, 2013 @ 4:44 am
Comment by Neil vN — March 5, 2013 @ 1:05 am
Neil,
I am hoping you can answer my questions. Would you know if I can use the st-e3 and 600ex-rt for manual output on “non-Canon” bodies, e.g. Leica R8, etc? I very much like the ability to change the manual flash power on the 600ex-rt using the st-e3. As you might have guessed, I don’t have a 600ex-rt and st-e3 available to check them out.
Thank You,
Kit
Comment by kit — April 29, 2013 @ 6:10 pm
Comment by Neil vN — April 29, 2013 @ 6:45 pm