Rudy Winston
Rudy Winston

Rudy Winston has over 14 years experience with Canon USA's Pro Products team, and has been responsible during that time for training Canon's staff on new products, creating presentations for customers and dealers, numerous writing projects, and providing technical assistance to professional and amateur photographers.

What's new in the Speedlite 600EX-RT

March 02, 2012

Canon's latest high-end flash, the Speedlite 600EX-RT, will make headlines for its world's-first built-in radio wireless capabilities. But even as a more orthodox flash-on-camera, there are a number of features which SLR enthusiasts and professionals should be aware of. We'll examine some of its highlight features here, with an eye (where possible) towards potential real-world applications where its new features and capabilities may be useful to working photographers.

Wireless E-TTL capabilities:

We explore its revolutionary radio transmission wireless flash possibilities at length in a separate article here on the Digital Learning Center. But to briefly summarize, the new Speedlite 600EX-RT gives users two fundamental options:

  • Optical Wireless E-TTL
    This is the same technology that Canon has used for off-camera, wireless flash since the 1998 launch of the Speedlite 550EX. Any Canon shooter who has worked with wireless flash up to now can simply add the 600EX-RT to their existing system, without any changes or loss of functionality. The 600EX-RT can act as a wireless "master" or "slave" unit, and can be mixed and matched with any other compatible EX-series Speedlite as an off-camera slave unit.
  • Radio Transmission Wireless E-TTL
    Here is an entirely new technology, separate from conventional optical-based wireless flash. With any EOS digital SLR except the original EOS-1D and EOS-1Ds models, full E-TTL automatic exposure flash is possible with anywhere from one to fifteen Speedlite 600EX-RT units positioned off-camera. Using radio transmission, they can be up to 98.4 feet (30m) from the "master" unit; the master can be another 600EX-RT on-camera, or the optional Speedlite Transmitter ST-E3-RT. And if combined with Canon's newest SLRs, such as the EOS-1D X or EOS 5D Mark III, the new "Group" mode can be used – allowing independent control of up to five separate groups of Speedlites off-camera.

Activating Wireless control is much easier, quicker and more intuitive on the Speedlite 600EX-RT. A separate, dedicated Wireless button is on the rear of the flash – each press (there's no need to hold it down for several seconds) toggles you through the following settings, in sequence:

Illuminated dot-matrix LCD panel:

Speedlite control is centered around a new LCD panel on the rear of the 600EX-RT. It's the first Canon Speedlite to offer dot-matrix LCD construction, allowing tremendous flexibility in terms of what is displayed, and integrating beautifully with the unit's wireless capabilities.

During wireless operation, by default, the color of the LCD panel's illumination changes when the Speedlite 600EX-RT is set as a master unit (green illumination) or slave unit (orange illumination) – so it's easy, at a glance, to tell with multiple flashes which has been previously set as a master or slave unit. This works for both optical and radio-based wireless operation; during normal flash-on-camera operation, by default, the illumination is also green. Using the Speedlite's new Personal Functions, it's possible to switch green or orange illumination during Normal, Master or Slave operation, as the photographer desires. There's also a Personal Function to adjust the contrast of the dot-matrix LCD display panel, further enhancing its potential depending on the situation that the 600EX-RT is being used in.

Contextual – and illuminated – button operation:

To handle its many functions, rather than encrust the rear of the flash with buttons, there are four primary buttons on the rear of the Speedlite 600EX-RT, positioned immediately below its rear LCD panel. On the dot-matrix LCD panel, the heading above each button labels its function, and changes depending upon how the Speedlite is set. In some instances, multiple functions require more than four buttons for access, so the far right-hand button becomes a "Menu" button, labeled "Menu 1", "Menu 2", and so on... pressing this button cycles through different on-screen settings and re-labels the remaining buttons as needed.

The Speedlite's buttons are illuminated; this is combined with the LCD panel's illumination. By default, the panel and buttons illuminate for about 12 seconds. Pressing any of the Speedlite's buttons, or turning the rear Select Dial, will activate the built-in illumination, making the buttons easy to find in total darkness. Via flash Custom Function 22, the user has three options:

  • 0: Default setting with 12-second illumination when any flash button is pressed
  • 1: llumination OFF (conserves a bit of battery power, or for situations where user is shooting in bright ambient light
  • 2: LCD panel and buttons always illuminated, as long as flash is turned on and is active
Beep when fully recycled:

When flash Custom Function 20 is activated (set to option "1"), Speedlite 600EX-RT will generate an audible beep when it is recycled. And, during radio-transmission wireless shooting, slave units will likewise produce a beep when recycled – one way to tell when a distant or hidden Speedlite in a wireless set-up is ready for the next picture.

Expanded flash zoom coverage:

Speedlite 600EX-RT now offers telephoto zoom coverage to 200mm, and on the wide end, will now cover a 20mm lens (with a full-frame camera; covers a 13mm or longer lens with APS-C sensor cameras) at its widest flash zoom setting. The separate pull-down panel for ultra-wide coverage with lenses as wide as 14mm (again, with a full-frame camera; full coverage with APS-C sensor cameras when a 9mm or longer lens is mounted) continues to be available.

The newly-expanded tele zoom coverage of the flash's illumination will be of particular interest to photographers using wireless E-TTL. Positioning one or more slave units well off-camera, and concentrating their illumination expands the range of possible effects a shooter can achieve on-location, especially when he or she is looking for a hard-edged lighting "look" mimicking sunlight. It can also be useful, when positioned closer to a subject, to achieve a bit of a spot effect.

And, the 20mm wide-angle setting will be of interest to press, wedding and event shooters, especially for flash-on-camera shots close to the subject(s), using wide-angle zooms like the EF 16-35mm or 17-40mm L-series lenses, or the EF-S 10-22mm lens with cameras like the EOS 7D. It will expand the possibilities for wide angle flash imagery, without requiring the separate 14mm pull-down panel (which broadens the flash beam beautifully, but cuts available power and distance).

Flash zooming, of course, offers a choice of automatic or manual operation. Pressing the Zm/C.Fn button highlights the zoom setting on the dot-matrix LCD display, at which point the control dial can be rotated to set the desired setting. As with previous Speedlites like the 580EX II, if the letter "M" appears next to a focal length number, it means the Speedlite is set for manual zoom operation; if no "M" is visible, the flash will automatically zoom to match the lens mounted.

Again, like recent EOS Speedlites, the 600EX-RT will by default accommodate the sensor size of the camera it's mounted to. The zoom position of the flash will automatically vary to account for the apparent increase in lens focal length when mounted on cameras with smaller than full-frame sensors. (This function can be turned off with flash Custom Function 9-1.)

Light distribution:
When set for automatic flash head zooming, users have a further control at their fingertips. The Speedlite 600EX-RT is the first Canon Speedlite to allow adjustments to light distribution at a given zoom setting. For example, assume the photographer is using a full-frame camera with a 50mm standard lens. He or she has these options:
  • Standard coverage (C.Fn 21-0)
    Flash angle of illumination will be virtually the same as with previous Speedlites, such as 580EX II. Normally, users can expect a slight degree of light fall-off from center to corner, although this usually is only noticeable when shooting straight into flat scenes or subjects, such as a wall.
  • Guide Number Priority (C.Fn 21-1)
    Flash will concentrate more power at center of the frame, and allow outer areas to fall-off more. This can actually be useful when shooting subjects with a telephoto lens, especially when outer areas are distant backgrounds that would tend to go dark anyway. The flash automatically zooms to a setting one step toward the telephoto end to achieve this; It's possible any time a lens from 20mm thru 135mm is used.
  • Even coverage (C.Fn 21-2)
    Here, the opposite happens – the Speedlite 600EX-RT automatically zooms its flash head one step wider than the detected lens actually is. The result is more even illumination, center to corner. This can be an especially useful setting for wedding and event photographers who take group photos, helping to insure well-lit subjects at the outer areas of the frame. It's available any time a lens 24mm or longer is detected on the camera (assuming a full-frame camera).
Color filters for flash:

Many pros have experienced shooting flash pictures on-location, and encountering yellow- or amber-colored backgrounds from tungsten ambient light in the scene. Putting a color filter over the flash head that matches the "color" of the background light, and then adjusting the camera's overall white balance for tungsten (or similar) lighting, is usually the answer. Until now, EOS shooters needed to use third-party gel filters, and apply any white balance adjustments manually – often, after some trail-and-error testing.

The Speedlite 600EX-RT makes the working pro's life a little easier here, too. It's supplied with a new, dedicated filter holder (Canon Color Filter Holder SCH-E1), which fits over the front of the flash unit. And, two separate pre-cut gel-type filters are also included, to assist in balancing flash with different levels of tungsten available light. Either gel filter can be fitted into the filter holder, and the pair then attached to the front of the Speedlite.

Two filters are included. One is a light amber filter, intended for mixed-light situations where daylight is a substantial part of the ambient illumination (but some tungsten indoor lighting also exists). And a deep amber filter, intended for indoor or night situations where the bulk of the lighting is tungsten artificial lighting, is also included.

The key new feature is that when an EOS camera is set to the FLASH white balance setting, the Speedlite 600EX-RT will communicate the new flash color temperature to the camera, and it will automatically adjust white balance to properly-render the flash (and presumably, the background) illumination. With the EOS 5D Mark III and EOS-1D X, the Auto White Balance setting can also be used. The filter holder and two sensors at the base of the flash head work in tandem to read and register any change in flash color with the filters in-place, and communicate it to recent EOS cameras.

A few points about the included color filters, and the automatic WB correction capabilities of the Speedlite 600EX-RT:

  • Using the filter holder does not change the flash angle of illumination
  • There's about a 1/3-stop light loss when using the light amber filter, and roughly a 1-stop light loss with the included deep amber filter. With E-TTL automatic flash, this is accounted for, but for manual flash exposure, be sure to allow for this reduction in effective flash guide number
  • Depending on ambient lighting conditions, White Balance Shift may need to be manually applied in-camera to fine-tune WB for optimum results
  • The automatic WB detection is intended only for these two Canon-supplied gel filters. Third-party 3x3-inch (75 x 75mm) gel filters can be cut to size by photographers and used in the Canon gel filter holder with the Speedlite 600EX-RT, but Canon strongly recommends turning off automatic WB detection of the filters (via flash Personal Function 5-1). Accurate WB detection (with the camera set for the FLASH WB setting) is not guaranteed with other filter colors, or with third-party amber-colored filters placed on the Speedlite.
  • The Canon filter holder for Speedlite 600EX-RT is required for any filter-on-flash WB detection; WB for flash with a filter cannot function if gel filters are simply taped or attached with velcro to the Speedlite 600EX-RT's flash head
  • Automatic WB correction, at the FLASH WB setting, is possible with the following EOS camera models only (as of March, 2012):
  • EOS-1D Mark III, Mark IV, EOS-1D X
    EOS-1Ds Mark III
    EOS 5D Mark II, Mark III
    EOS 7D
    EOS 60D, 50D, 40D
    EOS Rebel T3i, T2i, T1i
    EOS Rebel XSi, XS
  • Replacement Canon-brand amber gel filters are available through your Canon dealer. The set of two pre-cut gel filters is called Canon Color Filter Set SCF-E1.
Enhanced pro-level durability and reliability:

The new Speedlite 600EX-RT carries over design features seen in the Speedlite 580EX II, such as a metal flash "foot" and weather-resistant shrouding at the base of the Speedlite (no optional accessories are necessary for a weather-resistant hot shoe contact with cameras like Canon's EOS-1D Mark IV or EOS-1D X).

Furthermore, the Speedlite 600EX-RT is the most thoroughly weather-resistant Speedlite from Canon to date, with gasketing and sealing that matches the moisture- and dust-resistance of the EOS-1D X camera body. And, special attention has been paid to maintaining proper electronic contact at the hot shoe electronic connections. When the Speedlite's locking collar is rotated to secure it onto the camera's hot shoe, the plate with the five electronic contacts now literally moves forward and backward, rubbing the contacts on the hot shoe's contacts to insure that any dirt, dust or oily residue is "scraped" off and a solid electronic connection is achieved. This is the first time this has been done in an EOS Speedlite.

The shooting speed of many of today's digital cameras, and the widespread use of high-voltage battery packs for flashes to speed-up recycle times, have contributed to some photographers shooting flash pictures at rates more rapid than the Speedlite was designed for. While this can be done safely for brief periods, compact Speedlites simply don't have the internal space to allow heated components to adequately cool if they're fired repeatedly for prolonged periods – especially at or near full-power.

Speedlite 600EX-RT now has a sophisticated heat-detection system built-in to protect the flash tube, capacitors, and other internal components from damage from excessive internal heat. If heat sensors detect excessive heat, here's what happens:

  • "Level 1" – initial detection of excessive heat from continuous firing:
    The flash's recycle time will intentionally lengthen to about 8 seconds, allowing it time to cool off. Users are warned of this state by two means: on the LCD panel, above the Speedlite icon, two small "heat wave" icons appear. And, the illumination on the LCD panel continually appears in red. If the unit is allowed about 10 minutes of reduced firing or inactivity, normal operation will be restored.
  • "Level 2" – if flash continues to be fired continuously at high power levels:
    The flash recycle time is extended to about 20 seconds, allowing more time for it to cool between exposures. Three "heat wave" icons now appear above the flash icon on the dot-matrix LCD panel, and the entire LCD panel now blinks red as a clear warning that the Speedlite should be given a chance to cool off.
  • If Speedlite 600EX-RT's Custom Function 20 is active (BEEP enabled), the unit will also audibly beep when a firing restriction is active because of detection of excessive heat. In this case, the beep is three short, distinct beeps in a row.
  • These safety measures will be activated if the Speedlite 600EX-RT is fired repeatedly for approximately 30~35 times (when using an external battery pack); the precise number of flashes needed to trigger a Level 1 response will vary, depending upon flash duration, time between flashes, ambient temperature, whether the flash head is at a wide or telephoto position, and so on.

Unlike the previous Speedlite 580EX II, which also had internal heat detection sensors but would simply shut-down the flash entirely if they detected excessive heat (with no form of warning to the photographer), the 600EX-RT alerts the shooter as soon as excessive heat build-up is detected – allowing the photographer to continue shooting if he or she must, but providing a means to prevent costly damage to the Speedlite, and likewise giving the shooter notice that if circumstances allow, to either slow down their shooting, or switch the Speedlite(s) in use for a back-up unit if they must continue shooting at a fast pace.

Flash Custom Functions and – NEW – Personal Functions:

Speedlite 600EX-RT continues the tradition of excellent control by providing numerous Custom Functions built-in to the flash itself. Many of the Custom Functions in the 600EX-RT are similar or identical to those in previous high-end EOS Speedlites, and are numbered similarly.

Canon has added four completely new Custom Functions to the 600EX-RT, and these are numbered 20 through 23. For technical reasons, existing EOS cameras (such as the EOS 7D, EOS 5D Mark II, and so on) will be able to access all but these four new Custom Functions using the Flash Control Menu on the camera... the four new functions will require users to call-up Custom Functions on the 600EX-RT's LCD panel, and set them there. (New cameras, such as the EOS-1D X and EOS 5D Mark III, are able to access and control all Speedlite Custom Functions on the 600EX-RT.)

In addition, Canon has added seven new "Personal Functions" (P.Fn), allowing fundamental set-up of commands that aren't likely to be changed frequently in the midst of shooting – such as Speedlite LCD panel contrast or color, or whether the flash will fire or not during wireless radio "Linked Shooting". Regardless of the camera a Speedlite 600EX-RT is attached to, Personal Functions must be accessed and set on the Speedlite's LCD panel. The External Flash Menu on recent Canon EOS camera bodies won't be able to access Speedlite Personal Functions.

We'll discuss the Custom Functions and Personal Functions in-depth in a separate article on Canon USA's Digital Learning Center.

What hasn't changed:

Predictably, many significant features already present in previous high-end EOS Speedlites are carried over to the new Speedlite 600EX-RT. Some of these include:

  • Flash power
    The maximum guide number has increased, but that's because the Speedlite 600EX-RT now zooms to cover a 200mm lens rather than topping-out at 105mm, as the previous Speedlite 580EX II did. Zoomed to common settings, the guide numbers and effective flash power are virtually the same between the two flashes.
  • E-TTL features and capabilities
    Settings like Flash Exposure Lock (FEL), Hi-speed sync, Second-curtain sync, Flash Exposure Compensation, Flash Exposure Bracketing, and so on are all available and operated similarly in the Speedlite 600EX-RT.
  • Camera compatibility
    While some restrictions exist for Radio Transmission Wireless E-TTL, depending upon the camera being used, for ordinary flash-on-camera operation, the Speedlite 600EX-RT is compatible with every Canon EOS digital and film SLR ever made. It will also work on any Canon PowerShot digital camera having a standard hot shoe. E-TTL works with all cameras compatible with this flash method; with older film-based cameras, the Speedlite will revert to off-the-film TTL operation.
  • Battery and battery pack compatibility
    Speedlite 600EX-RT uses four AA-size batteries (alkalines, lithium, or rechargeable Ni-MH) in the Speedlite. It is also compatible with Canon's accessory Compact Battery Pack CP-E4, which holds an additional eight AAs. The connection socket for external power supplies is the same as previous 500-series EOS Speedlites.
  • Available flash shooting modes
    E-TTL (or E-TTL II, depending on the camera body), Manual, Multi (stroboscopic), and External Auto or "Manual" all remain available. When used as a single flash on camera, pressing the flash unit's MODE button toggles users through all the available flash modes; the External Auto modes no longer require activation in the Speedlite's Custom Functions.

To repeat, there are numerous functional improvements and added features that make the Speedlite 600EX-RT an appealing potential purchase to Canon EOS shooters. It's sensational radio-based Wireless E-TTL is truly an epoch-making feature to advanced photographers, but beyond that, it's the most capable and certainly one of the most intuitive units Canon has yet produced. Flash in general has become an increasingly important part of the work of many photographers, and here is a durable, reliable and capable Speedlite that stands ready to meet nearly any challenge that serious enthusiasts and professional shooters are likely to throw at it.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

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