Name: Canon ST-E3-RT Speedlite Transmitter, Version 3
Brand: Canon
SKU: CASTE33
Price: 319.00 USD
Availability: InStock
Rating: 4 (61 reviews)

Canon ST-E3-RT Speedlite Transmitter, Version 3

Canon ST-E3-RT

Canon

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Photography

Lighting & Studio

Optical Triggers

Camera & Flash Triggers

Canon Camera & Flash Triggers

Canon ST-E3-RT 

Get reliable TTL triggering with the Canon ST-E3-RT Speedlite Transmitter (Version 3). Long range, multi-channel, & fast recycle. Shop now!

For professional photographers seeking advanced flash control, the ST-E3-RT Speedlite Transmitter Version 3 is a powerful tool that supports Canon DSLRs with a standard hot shoe. This upgraded version maintains popular features from its predecessors, including wireless rear curtain synchronization, which captures stunning ambient light trails and conveys a sense of speed for moving subjects. The ST-E3-RT Speedlite Transmitter Version 3 boasts an impressive minimum output range, reaching as low as 1/8192 power, providing ample opportunity to work in low light conditions. The FE Memory feature is integrated into the radio transmitter, allowing you to lock-in an E-TTL flash exposure level even in complex multi-flash setups, and continue to use it for the same scene or subject.This device offers radio-controlled, two-way wireless transmission up to 98.4 feet, enabling control of up to five groups or fifteen individual Speedlites. The dot matrix LCD with backlighting, intuitive controls, and more, make this transmitter a user-friendly device for photographers at all levels.When used with the Speedlite EL-1, the ST-E3-RT Speedlite Transmitter Version 3 provides additional benefits such as wireless rear curtain synchronization, minimum flash power as low as 1/8192, and FE memory for storing E-TTL flash exposure. The ST-E3-RT Speedlite Transmitter Version 3 operates on 2.4 GHz frequencies, ensuring a reliable and robust connection among sender and receiver units. Unlike traditional wireless optical transmitters, it does not have directional limitations, making it a superior choice for ambitious photography.Supporting E-TTL II Flash, Manual Flash, Stroboscopic and Auto External Flash Metering, this transmitter allows control of up to fifteen Canon RT-compatible Speedlites in five groups from the camera, via a single transmitter. Each group can be set to a different flash mode, enabling multiple configurations for creative photography.The ST-E3-RT Speedlite Transmitter Version 3 features a dot matrix LCD panel that displays all pertinent information simultaneously. The backlit control panel and internal sound emitter make it easy to operate in both daylight and dark conditions. With eight types of custom functions and three types of personal functions, this transmitter can be configured to meet various shooting demands. The high-performance hot shoe contacts ensure reliable information transmission and operation. Its dust and water-resistant design ensures uninterrupted performance in harsh conditions, making the ST-E3-RT Speedlite Transmitter Version 3 a durable and versatile tool for professional photography.

I am not sure how three people gave bad reviews about having link problems. I have used this and the former model and the new R model and have never had a problem. I use the flashes in nature photography often in tough environments; sometimes with up to six flashes though normally with 2 or 3. They perform with great precision and never had a problem of any type. As a professional photographer I rely on this system and can highly recommend it for all flash uses.

Great reliability and features.

The canon radio "RT" system is completely useless. Whatever radio frequency they use is completely crowded now in 2025. You will get inconsistent connections. Their speedlites constantly loose "link" in the middle of events. This has been an issue for many years and there is still no fix.

Not reliable and constant dropped connections

Bought this a few years back, along with the 600EX II -RT. I didn't get a chance to use them much until recently. So far it's been terrible. I keep losing connection with them within minutes. I went online to see if this is a common issue, and BOY is it (go to message boards and YouTube and you'll see a LOT of angry photographers with the exact same problem). Worst part is Canon's 'customer service' has clearly shown that it could care less. You would think with this many dissatisfied customers Canon would genuinely address the issue, but nope. I will tell everyone I know NEVER buy a single Canon product again, nothing (I will be on social media telling my story as well). Any company that shows this kind of contempt towards it's paying customers, is NO company ANYONE should EVER do business with! I'm going with Nikon and Godox from now on.

ST-E3-RT w/Canon Speedlite Is a Complete Failure.

As the other reviews state it drops connection way too often. I expect better from Canon. HOWEVER that's on auto channel, if you pick one manually it works better (thus 3 stars) but it still drops it sometimes. Just did a 2 hour photo shoot and it dropped 2 times. If you don't already have canon flashes I would recommend the Godx System from B and H. Most professionals recommend it.

Drops signal

Why are they selling this garbage? Never holds a connection,  if you're lucky enough to get one at all.

do not buy

The whole flash system is unreliable.  They will lose connection in a newer wifi environment.  I used to rely on this system, but no more.  Canon will not even acknolwedge the issues, even though the customer forum has hundreds of posts on this topic.

Unreliable

Very inconstant. If you want to look bad by constantly having to apologize to your client for switching on and off the transmitter and hoping that the light turns green and the flashes finally fire than buy this.

Terrible

Flash trigger will drop connection with Canon Flashes at random times. The only way to fix this is to turn everything off and restart or by resetting the link again. The system will then go down again for a few minutes or not at all and in some cases I have to reset every couple of minutes making it impossible to use. Everything works perfect when testing but almost inevitably the link will drop again while shooting. When it works it works amazing but when it doesn't it's very unreliable. I hear Canon has known about this for over 1 year and has done nothing to fix the problem. Is there a software update that can fix this issue? a recall maybe? please help.

Radio transmission link drops VERY often.

These transmitters used to work flawlessly but in the past 1-2 years there have been multiple complaints that the transmitter signal is dropped by the flash and the flash will not fire unless you constantly turn the transmitter and the flash on and off. Canon has known about this problem for years and has done nothing to fix it!

DON'T WASTE YOUR MONEY

Flash trigger will drop connection with Canon Flashes after 1 minute. The only way to fix this is to turn everything off and restart. The system will then go down again in about 1 minute. Canon has known about this for over 1 year and has done nothing to fix the problem. I would give it zero stars if I could.

Worthless Piece of Junk

Works great. More compact than pictures make it seem.

Good buy

I purchased the Canon ST-E3-RT Speedlite Transmitter, Version 2 on a Sunday and received a package from Adorama on Monday!  Wow, that is great customer service!  I also bought a Canon EOS R6 from Adorama and it arrived surprisingly quickly and in great shape.  

The product works great with my Canon gear.  I am a hobbyist and found the product easy to use....really easy! 

I would also like to commend Adorma for the updates about the status of my order and expected delivery as well as their commitment to post support.

Great job, Adorama!

Great company, great customer support, great service - highly recommen,d

Well it works flawlessly with my 600ex-II’s.  I bit on the pricey side but I trust canon quality so I stayed with what I know.

Works like a charm

Awesome Canon transmitter.  Easy to setup and never fails.   Thanks Adorama!

Excellent and Reliable.

Works very well. Have had a little problem with it losing radio connection with flashes but since running a frequency scan and finding a stronger radio channel problem hasn’t returned!

Recommended Purchase

Be very careful about the ON/LOCK/OFF switch. This tiny snap-in part can pop-off and be lost, thus  disabling your ST-E3-RT and Canon does not provide a spare part. Canon repair estimate runs about 1/3 price of new transmitter. Mine must have popped off when I was putting the transmitter back in its case. Once this lever is off, the switch contact is free floating inside. Not just free to rotate, but free to slide around in any direction. So even if you try to set it using a paper clip, any movement can cause it to power off, or lock, or come back on. For the price, I would expect something more robust. Very disappointed Canon doesn't even provide the spare part. I have used the Chinese knock off with the focus assist. It was OK, but 10% of time it didn't trigger my flash. I would recommend this over the knock-off with the caveat about extra special care when operating the switch or putting the unit back in it's case. I do shoot mostly available light or with studio flash. If i had to use this a lot, I would look to switch brands to Nikon or Sony (Cameras and lenses) if they make something sturdier. My 5D mkII and 1Dx are very sturdy and reliable, my telephoto lenses were rock solid. This is unit is a fragile, throw-away, plastic toy.

Fragile plastic toy

Canon you did it again, great , simple and easy to work with

Transmiter

Canon should quickly bring the next version and without cutting down any of the exsting features, must add focus assist also. Usually this product gets used in low light situations and this is a must feature. Also, please do not cut any features, instead add more. Otherwise Canon should not complain that the "market is declining".

Good, but need focus assist

I was surprised how easy it was to establish great connection between my camera and my flash. It was also so easy to do that with my three flashes at the same time. Either easy connection all on one group, or group each one on it's own group from A to C. It works without interoption every sigle time. I love the abilities it gives me. My small portable studio weights less than 30 lb and it has background stand, backgrounds, two flashes stands with umbrelas and three flahes as well my camera. Thanks to Canon's RT Wireless Flash System everything works together. I really enjoy working with Canon RT Wireless Flash System and definetely would recommend to proffeesionals and hobbysts alike.

Robust connection, easy to use

I use the ST-E3 to fire (2) 430EX III-RT speedlights mainly in manual flash mode.  I assign each speedlight to a separate "group" and am able to control output from each light separately.  Nice to be able to remotely adjust light output.  It pays to read the manual and set the custom functions to suite you.  I prefer the orange light on the display rather than the default green which can be a little difficult to read.  Like having transmitter oriented with horizontal display/controls so it doesn't stick up too high above camera hot shoe.  Considered the Yongnuo alternative but decided to keep all my equipment Canon.  Unit is Canon quality as expected.  Have not had too many opportunities to use in actual shoots but so far so good.

Works Great!

Easy learning curve. Tons of tutorials on utube. I like how easy it is to control my flashes.  Yes it is pricey.

Great transmitter

Having been behind the camera for over 45 years I have made my share mistakes. When I started out as a teenager, sure the cheaper options fit better into my meager budget, if there ever was such a thing as a budget. One had to scrimp and save up for what you wanted to purchase and by the time you were able to afford it, it was already at the end of it's life cycle and something new was introduced to take its place. Although these devices do have their application, I have since learned for me, it is less costly in the long run to stay with one brand and run with it. Hey either you are a dedicated Canon shooter of a dedicated Nikon shooter. That was a choice we make when we are faced with the decision as to which system is best to fill our own specific needs.  

O.E.M. manufacturer's sometimes have issues with their gear performing up to claimed specs which require tweaking, how much more for third party manufacturer's trying to emulate the original product. At least when one stays with one brand, troubleshooting becomes so much easier and there is less finger pointing trying to blame other manufacturer's for causing the problem. When everything is all under one roof, the problem is more likely to get resolved and one can get on with being productive once again. 

In today's day and age with information sharing so readily available, did you ever notice how radio frequency devices all appear to be "proprietary" having their own "special" frequency. This often makes things complicated for devices to communicate with one another and if they do, results can be erratic and unpredictable. With optical triggers, if the trigger was not in the direct line if the flash , it simply did not fire until it was brought into range. Who knows what really is happening in cyberspace with radio devices??? If it were not for flexible store return/exchange policies, the junk draw would overflow with incompatible tools that don't work as we need them to. 

Now about the ST-E3-RT Speedlite Transmitter. Things could not be easier to use. It consistently fires. It is basically a 600EX-RT but without the flash head. There is also no learning curve to try and figure out how the device operates or to try and program it to emulate the flash so that they can try to communicate. It's like plug-n-play. How much simpler can you get. 

When time is money, the time saved is money saved. In addition, Canon devices are often often engineered to be backwards compatible, albeit like everything else, to a point. With the return of film, I can't wait to take my trusty old Canon A1 out of retirement and have some fun. I anticipate the results will be just as spectacular even if some modes of operation may not likely operate on such a vintage camera in which the technology was not invented till decades later. If only we had something like this way back then.

C.Y. R.

Great range!  Syncs with the speedlite seamlessly.  Light weight, easy to use.  Little pricey but totally worth it.

Great Transmitter!

The speedlite transmitter worked great so far with the430EX III-RT. I only used it twice just to check it out. I like it hope to use it more offend.

st-e3-rt speedlite transmitter

This transmitter is so incredibly easy to use. It is just what I needed to get my flash off of my camera and get my light source where I need it.

Sppedlite Transmitter

I love the Canon ST-E3-RT! I can do much more as well as get better and more fun results!

Wanna make your life easier?

This is a "Radio" transmitter for higher end Canon Speedlites. It is phenomenal!  It's easy to use and can trigger multiple speedlites.  You do not meed line of sight like infrared triggers.  This can work anywhere where radio signals work. It's a must have for off camera flash shots.

A Must have for Serious Canon Photographers

Very happy with this purchase.  Makes using a remote flash extremely easy.

Excellent Tool

I do photostacking of flowers, and at times I need more light for my macro lens, since I shoot a lot in the morning to keep the wind down! This is THE transmitter for my Canon 600EX RT flash- they work well together! Very easy to set up and use, and lots of wonderful features!

Canon ST-E3-RT Speedlite Transmitter, Version 3

Key Features

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