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How to Use Your Canon Speedlite 600EX-RT

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Read Time: 14 min

The introduction of radio for flash triggering in Canon starts with the Speedlite 600EX-RT, a flash that opens new horizons but also forces users to learn a few new things. Here are the most important thing to know about your Speedlite 600EX-RT.

Meet the 600EX-RT

If you're in the market for a new flash system, are a Canon user and want to go to the top of the line, buying the Speedlite 600ES-RT may be your best bet. It stills "talks" with older Canon flashes in optical mode, but is a step into the future and the most reliable system for flash triggering: radio frequencies.

Canon has adopted the universal frequency of 2.4GHz, used almost everywhere without any problems. Chinese flash trigger makers, who pushed the market in the radio direction with a multitude of products, use the same frequency. So the new unit is the starting point of a new generation.


There's a steep learning curve when you move to this new flash system from Canon, especially if you come from the older models, like the 580EX II or 430EX II. These had cryptic interfaces that needed the manual close by to be decoded.

Fortunately Canon started to use the LCD on their recent cameras - as far back as the EOSD 40D - to control external flashes, so it was possible to create more user friendly interfaces that made the use of flash easier. This means that you also can control your new flash or flashes directly from your camera, although some limitations apply to cameras introduced before 2011.

A Larger, Better LCD

The 600EX-RT enters a new line of thinking, as the unit lets you work in two modes, optical and radio, offering multiple options within each type of control. This said, the interface is easier to understand, due to the bigger LCD, which permits the use of plain English to explain the functions (instead of codes you had either to remember or look up in the manual).

The new Speedlite 600RT really "speaks" to you, making for an easier use once you come to grips with all the new functions.

Also, Canon has ditched making users tap on different buttons multiple times to get functions, providing users with an interface that changes according to the mode in use, followed by a change on the way buttons behave.

The Mode button changes the interface and the functions each "soft" button activates. And that all is explained in a language understood by humans instead of just computer programmers from 1988. The new Speedlite 600RT really "speaks" to you, making for an easier use once you come to grips with all the new functions.

canon600ex_02The old Speedlite 580EX II and the new Speedlite 600EX-RT interfaces.

Five Working Modes

Let's look at the new unit, starting with the back, where the new, bigger panel dominates. There are almost the same number of buttons that you find on the previous top of the line, 580 EX II, but there are new ways to use them.

Once the unit is turned on (the lever on the right side) you can access the different modes using the large button on the left. It will take you through the ETTL, Manual, Multi (Stroboscopic), External Automatic and External Metering modes. Some of these modes people never knew about, simply because they were hidden in the submenus under the cryptic functions on the 580 EX II.

Because we're just looking at the essential aspects of using the 600EX-RT, we will not explore the three last modes, but center on those most people will want to use: ETTL, where the flash automatically defines the light needed, based on a meter reading done through the lens, and Manual, where you set the amount of light emitted and adjust exposure accordingly.

canon600ex_03You can choose the colour of the backlit LCD: green or yellow. It's good way to identify which unit is the master and which is the slave, for example.

Using ETTL

Once you choose the ETTL mode, the functions available to each button show up on the LCD. And they are Zoom/Functions, Exposure Compensation, FEB (Flash Exposure Bracketing) and Sync, with defines if you get 1st or 2nd curtain sync or if you go to the Hi-Speed mode. On the center of the LCD you get a scale for Exposure Compensation and at the bottom the distance the flash will reach, both similar to what you had before.

Besides choosing the zoom of the flash head (automatically and manually from 20 to 200mm), you can access both the Custom and Personal functions through the first button. These functions now have easy-to-understand menu descriptions, so you can leave the manual home after once you've read it once or twice.

Going Manual

Once you choose Manual Mode, the third button from the left stops letting you do FEB, which makes sense since you're working on manual and fully controlling the flash charge to be emitted. The scale in the middle of the screen changes to show you the power settings you can adjust, from 1/1 to 1/128 in 1/3 stop increments.

Press the button below the +/- sign and you can adjust the power using the selection dial in the center of the 600EX-RT.

Press the button below the +/- sign and you can adjust the power using the selection dial in the center of the 600EX-RT. Press the SEL/SET button to lock in your adjustment. This is the normal procedure to adjust many of the options on the 600EX-RT.

canon600ex_06The Speedlite 600EX-RT makes a nice pair with the Speedlite Transmitter ST-E3-RT and frees your flash from the camera hot shoe.


On the right side of the back of the unit, you'll find the ON/OFF switch, now with a new LOCK feature. Using it prevents the settings from being changed, a welcome option. To regain control of the buttons you need to UNLOCK the system again.

You also have the option to Save settings, a good option if you use consistently the same settings in your work. By pressing the two middle buttons on the back of the 600EX-RT you can CLEAR, any settings, returning the unit to the normal shooting mode, in ETTL.

Wireless We Go

Going back to the left side you'll find a new button there, for the wireless transmission. On the same side you'll find a flash ready lamp. Red confirms the flash is fully charged, and green shows it is ready for quick flash, which enables you to shoot even before the flash is fully charged while losing some power. This same button doubles has the test button.

The little light on the other side of the selection dial confirms the flash exposure each time you shoot. Knowing well what each button and dial on the back of your 600EX-RT does will be of great help to get the best shots. Once you learn the technique, you just need to care about the creative aspect.

Pressing the Wireless button you access the two modes available, optical and radio. The LCD will show, on the right side, either the usual icon for optical or an antenna, so you know you're using radio.

To fully explore these wireless options, you need to have two flashes, one on the camera to work as the master and a second unit or slave, that can be placed anywhere you need it.


Master and Slave

When you use two flashes you discover you have a new set of functions to control, mainly the different flash groups, which can go up to 5 with a total of 15 flashes in some configurations. You'll probably just start with two flashes, and then you'll discover that you can control the ratio between the two flashes, defining exactly the amount of light each delivers. But you can also set one flash or group to work in Manual mode, and the other in ETTL, according to your needs at the moment or preferences.

If you're using two 600EX-RT flashes, you just press the Wireless button on the unit to be used as Master, until you get the antenna for radio and "master" shows on the LCD. Then do the same on the slave unit (keep pressing the Wireless button), until you get the antenna and the word "slave."

The green LINK light above the LCD will show, meaning they're working and you'll hear a BEEP. If nothing happens, remember to check that you're using the same channel and ID on both units!

Take some time to explore all the possibilities of this setup. The interactive interface makes it easy to understand what is going on. Looking at the labels that appear next to each button will explain the options available. If you get lost, just press the Wireless button again to get back to normal shooting, and start again.

One nice feature of the 600EX-RT is that you can choose the color for the LCD backlight between green and yellow. It's not just a cosmetic option, because you can set your master to green and the slave to yellow. With just two flashes it is simple to remember which is which, but in complex configurations with multiple flashes is good to be able to just look at the LCD and know immediately the mode in which the flash is working. And yes, it looks cool!


Using the ST-E3-RT

Using two flashes is a viable solution, although a rather expensive one, especially if you are starting to learn to use flash or prefer to work with a single unit. What makes sense for many people is to buy a Speedlite Transmitter that sits in the hot shoe of your camera and communicates with the Speedlite 600EX-RT.

Canon has created exactly what you need with the ST-E3-RT, a control unit that has an LCD and controls exactly like the 600EX-RT, but does not have the flash head. Using the ST-E3-RT as a master, you can begin to play with your new toy. And once you've learned to use the 600EX, you know the ST-E3-RT by heart.

There is one thing that puzzles me and makes the ST-E3-RT problematic for photographers working in low-light situations. Contrary to the previous ST-E2, which had an AF-Assist Beam to help the camera focus in the dark, the ST-E3-RT does not.

Six Quick Tips on Compatibility

There are a few points that are important to remember about the new Speedlite 600RT:

  • It can only work in radio or optical mode, not both simultaneously.
  • With Canon EOS cameras before 2012 it lowers the maximum sync speed one stop, meaning that instead of 1/250 you get 1/125, or whatever is your sync is.
  • If you have a 600EX-RT and an EOS 7D, 60D, or 600D you can control your 600EX-RT wirelessly, in the optical mode.
  • If you've a 600EX-RT and a Canon EOS 1Dx or 5D Mark III you cannot control your flash without using another 600EX-RT or the ST-E3 transmitter on the camera.
  • You can use the 600EX-RT with older Canon flashes, but only in optical mode.
  • If you use the 600EX-RT and older flashes and do not want to use any of them on the camera, you need to buy the older ST-E2 optical transmitter, as the ST-E3 only works in radio mode.

Mapping the Speedlite 600EX-RT

Understanding the interface on a flash is the best way to make it easier to work with. The new Canon Speedlite 600EX-RT has a lot of new functions that made it necessary to have a complex menu, but the interface is easy, once you get to know it. We present here some of the most common functions.

The figure on the left (Green LCD) shows some of the information you see on the LCD when the flash is directly connected to the camera, either on the hot shoe or through a cable.

  1. The LINK light confirmation lamp only shows green when you're working in Radio mode and all your flashes are communicating. Otherwise, it will either be off or glow red.
  2. On the LCD, the first line of info shows the mode you're in (ETTL, Manual or any of the five modes mentioned in the article. The second block of information tells if the flash head is working in Auto or Manual, and the zoom in use.
  3. The flash icon on the left shows that the flash is working in Standard mode. According to the mode in use, you'll have different icons showing there. The scale to the right of it shows the flash exposure level. To adjust that scale you press the second button on the row just under the panel, and then rotate the selection wheel and press the inner area, SET (11).
  4. The line at the bottom is a scale (in feet or meters, defined by the user) showing the range of the flash according to the values in use. Under it you find the information for the interactive menu. These options change according to the mode in use, changing what each of the four buttons under the LCD do. The two center buttons CLEAR any settings when pressed at the same time.
  5. Press this button to activate the wireless mode or linked shooting (an advanced mode to use multiple cameras and flashes). Each new tap on the button shows a different option for both radio or optical flash communication.
  6. The mode button has a new position and is bigger. It gives access to the different shooting modes and changes the interactive menu accordingly.
  7. The flash ready lamp glows red when the flash is ready to fire. It doubles has a test button.
  8. The flash exposure confirmation lamp lights briefly after each shot to confirm the exposure was right. The flash on the right side of the image is working away from the camera, in slave mode.
  9. The flash icon on the left side of the LCD indicates the flash is working in slave mode. In the center of the LCD you see the word "slave." A master unit would have that "master" showing there.
  10. The lightning icon indicates the flash is working in the optical mode. For the radio mode, an antenna appears at the same place. Under it appears the channel number.
  11. The A on the left indicates the Group the flash belongs to. In normal conditions, you can have three different groups in Canon Speedlite system. The scale indicates if some flash exposure compensation is set for Group A.
  12. The interactive menu has changed compared to the LCD of the single unit on the hot shoe of the camera (see 4). The button on the right side gives access to the different menus of the Speedlite 600EX-RT.
  13. The Selection dial in the center rotates both ways to adjust values present on the LCD. To confirm your choices press the set button in the center.
  14. The On/Off lever has a new function: lock. It disables button and dial operations. Use it to prevent the flash settings from being accidentally changed after you've set them.

This short explanation of the Canon Speedlite 600EX-RT does not cover all the functions the unit offers, but gives you a good, solid understanding of the most common functions used by most photographers.

A Simple Example

canon600ex_07a The ambient light shot was interesting, but I wanted to get the bench lit, as the main point of interest in the picture.

The example published here is a good look of what the system does. The aim was to brighten the bench in the park while keeping the low light ambiance. With only one Speedlite 600EX-RT and the Speedlite Transmitter ST-E3-RT, you're able to free the flash from the camera and get a mix of ambient and artificial light that would not be possible to obtain with the flash on your camera.

The flash was hidden behind the tree on the left side, and that means that the line of sight needed for an optical system to work would not be available, meaning the shot could not be done. With a radio system like this, you're free to place your flash anywhere because the radio waves provide reliable communication between the camera and the external flash unit.

canon600ex_08aSo I placed a flash behind the tree, lowered slightly the exposure for the ambient light and introduced the flash exposure, just enough to simulate the look sunrays coming down through the trees would create.

This solution offered by radio systems to trigger flashes is a step forward in terms of freedom for photographers because you can hide your flashes anywhere: behind walls, outside to shoot through windows. The limit is around 100 meters in open space and about 30 meters in closed areas.

From my experience testing the system and my daily experience with radio flash triggers, the misfire associated with optical systems is gone for good. That is one of the reasons why I prefer to use radio triggers even if I have "line of sight" between the flashes and the camera. Why bother with optical if you can have a more reliable system?

One last note. There is a version of this Speedlite without radio. It is called the Speedlite 600EX. It offers all the options of the new unit with the radio triggering options.

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