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What's New: Canon Speedlite 600EX II-RT

Canon Speedlite 600EX II-RT with CTO Filter

Canon Speedlite 600EX II-RT

By: Rudy Winston

May 11, 2016

Canon’s engineers changed the digital SLR landscape with the Speedlite 600EX-RT and its revolutionary, built-in radio-based wireless flash capabilities.  Introduced in 2012, this flash has become a gold standard in the industry, and has enabled many serious photographers to “raise their game” in off-camera flash capability, while preserving the option of E-TTL automatic flash exposure control, through the camera. 

In the ensuing four years, Canon has listened to feedback from serious enthusiasts and professionals, and with that input has created the next-generation, top-of-the-line Canon E-TTL flash unit:  the Speedlite 600EX II-RT.

canon speedlite 600EX II-RT front canon speedlite 600EX II_RT back

Speedlite 600EX II-RT looks almost identical on the exterior to the previous 600EX-RT, which it replaces in the Canon line-up.  A rear view (with the flash on its included mini-stand) shows the control layout to likewise be identical to its predecessor. However, the 600EX II-RT provides updates in reliability and heat resistance, operational convenience, and accessory compatibility.  And, it provides the wireless, off-camera operation features that made the previous 600EX-RT such a significant development in the digital SLR marketplace.


In this document, we’ll give an overview of what’s new and different, and likewise paint a picture of what remains unchanged.  As the product name might suggest, this is an evolutionary update, and not a radical new product introduction.  The Speedlite 600EX II-RT will replace the 600EX-RT in the Canon line-up, upon its introduction to the market later in 2016.  Parenthetically, unlike the 600EX-RT, this newly-updated 600EX II-RT will not have a companion “non-RT” version for sale in limited parts of the world… only a radio-compatible 600EX II-RT is being introduced, world-wide, at this time.


Quick summary: what’s new and different

•     Increased flash reliability — more continuous flashes possible;  greater resistance from heat during rapid firing

•     Added continuous flash shooting possible if connected to updated Canon Compact Battery Pack CP-E4N — introduced along with Speedlite 600EX II-RT

•     Separate hard-type white balance filters (deep amber, and light amber color) replace the gelatin-type filters and dedicated holder of previous 600EX-RT

•     New, dedicated diffuser attachment, called Bounce Adapter, included with 600EX II-RT  (can be combined with either of the included hard-type amber color filters)

•     Revised, dot-matrix LCD interface:
   — Recycle indicator appears during recycle period, showing relative level of recycle
   — Flash Exposure Mode choices now displayed over larger screen area during selection
   — Wireless Flash Mode choices now displayed over larger screen area during selection
   — Button and Dial selection of Flash exposure mode and Wireless operation mode when the enlarged screen is dispalyed  (minimizes the risk of accidental setting changes which could occur with the previous 600EX-RT if a button was accidentally hit during shooting)

dot-matrix LCD interface

An example of streamlined operation: when the MODE or Wireless buttons are pressed, instead of having to cycle through small icons on the flash’s LCD panel, the Speedlite 600EX II-RT changes the display on its LCD panel to a larger one, clearly showing the available settings. And, instead of multiple button presses to select the user’s choice, when the appropriate button is pressed once and the display appears, turn the Select Dial on the flash to highlight your choice, then press the flash’s SET button to lock it in, and return to a standard flash LCD panel display.


•     Flash firing control modified — “Quick Flash” feature (allows flash to fire when partially recycled, during recycle process) now active if camera set to Continuous drive advance;  this can be disabled with a flash Personal Function (P.Fn 05–1)

•     Radio-based wireless master operation slightly changed:  with 600EX II-RT as a master unit, if camera is fired and one (or more) off-camera flashes have not fully recycled, those flashes that are recycled will fire.  (Previously, ST-E3-RT or 600EX-RT as master unit would not allow any flashes to fire until all had reported as fully recycled… any shot taken before all slave units fully recycled would be using ambient exposure only.)

•     Linked shooting:  600EX II-RT cannot be used with older “slave cameras” introduced before 2012*.  (600EX II-RT has no socket for optional SR-N3 connecting cord to camera’s remote control socket, which was required with older cameras and previous 600EX-RT.)

      * EOS cameras introduced in 2012 or later (compatible with Linked shooting and Speedlite 600EX II-RT):
     — EOS Rebel T4i and above;  EOS Rebel SL1
     — EOS 70D and above
     — EOS 7D Mark II
     — EOS 6D
     — EOS 5D Mark III;  EOS 5DS and 5DS R
     — EOS-1D X and above


What remains the same as in previous Speedlite 600EX-RT

•     Flash power level and guide numbers

•     Flash angle of coverage  (20–200mm equivalent, with full-frame camera;  separate ultra-wide 14mm equivalent angle of coverage with separate pull-down panel)

•     Bounce and swivel operation, including -7° down bounce option for close-up shooting with flash on-camera

•     AF Assist Beam operation, distance range, and coverage

•     Basic flash recycle time, using four alkaline AA batteries (for both normal flash firing, and Quick Flash operation)

•     Flash exposure mode choices 
   — E-TTL automatic flash exposure
   — “Off-the-film” TTL  (with older 35mm film-type EOS SLRs)
   — Manual flash  (full 1/1 thru 1/128 power selectable)
   — Multi mode  (stroboscopic flash)
   — External, non-TTL Auto  (“Auto” interaction with compatible EOS SLRs)
   — External, non-TTL Auto  (“Manual” interaction with all EOS SLRs)

•     Basic flash control and button layout, including Select Dial on rear of unit

•     Size and weight — not completely identical, but very similar to previous 600EX-RT

•     Weather-resistant design:  Speedlite 600EX II-RT matches the weather-resistance of Canon’s EOS-1D series cameras

•     AA battery compatibility in the speedlite  (four AA batteries:  alkaline or rechargeable NiMH;  please note that Canon recommends that disposable lithium-type AA batteries not be used in any Canon speedlites or battery packs)

•     Compatibility with previous Canon-brand external battery packs (eight AA batteries):  CP-E3 and CP-E4  (note:  these do not support the updated continuous, repeated flash firing of Speedlite 600EX II-RT, and are compatible for less-demanding flash firing applications only)

•     Radio-based and optical-based wireless flash operation

weather and dust resistant seals and gaskets on speedlite 600EX II-RT

One of the design features of recent top-of-the-line Canon EX-series speedlites is weather-resistance. Like the previous 600EX-RT, the updated Speedlite 600EX II-RT has a network of weather- and dust-resistant seals and gaskets, giving it a level of protection from harsh environments matching that of EOS-1D series cameras.



Wireless flash compatibility with existing Canon speedlites

Fear not — both radio-based Wireless E-TTL, and traditional optical-type wireless flash with the Speedlite 600EX II-RT are totally compatible with your existing EX-series Canon speedlites.  You can add one or more of the updated 600EX II-RT units to any existing combination of Canon speedlites and/or transmitters you currently use, and continue to use them in the same way.

For radio-based wireless operation, the 600EX II-RT operates as both an off-camera “slave unit” or an on-camera triggering device (“master unit”), and can be used in conjunction with the existing Speedlite Transmitter ST-E3-RT and recently-updated Speedlite 430EX III-RT, as well as any of the previous-version Speedlite 600EX-RT flashes you may have in your system.

There are no changes in basic radio-based wireless flash capability.  Briefly, these include:

•     Communication with off-camera flashes up to approx. 98.4 feet/30 meters from on-camera “master unit,” over 360° range

•     Up to 16 total radio-based Canon devices (master units and slave units) in a single wireless flash set-up

•     Master unit(s) can be Speedlite 600EX II-RT, Speedlite 430EX III-RT, Speedlite Transmitter ST-E3-RT, or previous Speedlite 600EX-RT

•     Wireless E-TTL automatic flash exposure with radio-based transmission to off-camera speedlites, with all EOS digital SLRs (except original EOS-1D — 4 million pixel version, and original EOS-1Ds — 11 million pixel version)

•     Same flash ratio options:
   — ALL  (all flashes fire at even power level)
   — Ratio  (A:B ratio between 2 groups of flashes, or A:B:C ratio between 3 groups)
   — Group Mode  (up to 5 independent groups of flashes — requires EOS cameras introduced from 2012 or later*)

•     Full flash sync up to camera’s fastest x-sync speed, and option for Hi-speed Sync up to camera’s fastest possible shutter speed (requires EOS cameras introduced from 2012 or later*)

•     Same 2.4 GHz radio transmission method  (15 available channels;  individual wireless system IDs from 0000 thru 9999 are user-selectable)

•     Same Remote Release capability (fire one camera, pressing a button on one of slave units in a radio-based wireless flash set-up)

•     Same Linked Shot capability (fire up to 15 “slave cameras,” with mounted radio-based speedlite or ST-E3-RT, when one “master camera” with speedlite or transmitter is fired);  note that 600EX II-RT will require mounting to an EOS camera introduced 2012 or later*

Simply stated, Speedlite 600EX II-RT changes almost nothing in operation and functionality for either radio-based wireless flash, or traditional optical-type wireless flash operation.  The only known restriction with the 600EX II-RT is the previously-mentioned lack of an external socket for connection cord SR-N3 to older EOS SLRs, for Linked Shot operation.

Likewise, optical-type wireless flash continues unchanged.  And, as with the previous Speedlite 600EX-RT, it is not possible to combine Canon’s radio-based Wireless E-TTL with optical-type wireless flash, for use in the same picture.


Continuous flash firing

Speedlite 600EX II-RT introduces a series of design changes to increase the number of continuous shots that can be fired, without interruption, before the advent of any heat-protection measures.  For example:  at full, 1/1 manual power level, with flash head zoomed to 35mm position:

•     Speedlite 600EX II-RT:  100 flashes before Level 1 firing restriction
•     Speedlite 600EX-RT:  74 flashes before Level 1 restriction

Changes that make this possible include a newly-designed flash head with a fresnel lens designed to resist heat build-up from the flash tube;  new heat radiating materials surrounding the flash tube;  and a change in plastic materials throughout the flash head to further resist heat build-up during repeated flash firing in demanding shooting situations.


Continuous flash firing with Compact Battery Pack CP-E4N

Along with Speedlite 600EX II-RT, Canon is introducing an updated external battery pack, called the Compact Battery Pack CP-E4N.  We’ll have a separate article about it on the Canon USA Digital Learning Center web site, but its chief design change is its own support for continuous firing with the Speedlite 600EX II-RT.

When the 600EX II-RT is combined with this new CP-E4N external battery pack, the relative increase in number of safe, repeated continuous flashes is even more apparent:  the electronics in older Canon Compact Battery Packs could not support this type of continuous, repeated shooting — even though they did speed up basic flash recycle time.  Please note that if the CP-E4 (previous-generation battery pack) is attached to the 600EX II-RT, the flash will limit continuous firing performance, to resist heat build-up within the external battery pack.

Again, at full, 1/1 manual flash power, and flash head zoomed to the 35mm coverage position:

•     Speedlite 600EX II-RT with CP-E4N:  100 flashes before Level 1 firing restriction
•     Speedlite 600EX II-RT with previous CP-E4:  70 flashes before Level 1 restriction


More flashes before reaching Level 1 flash firing restriction

With the previous Speedlite 600EX-RT, a built-in protection system could sense internal heat build-up at various locations within the flash, and once a certain threshold of internal heat was reached, it would enter “Level 1” flash restriction.  This would intentionally act to prevent further heat build-up by lengthening flash recycle time to 8 seconds, giving added time for heat dissipation between shots in high-demand shooting situations.  Users were warned on the 600EX-RT’s LCD panel, with an icon appearing, and a change in panel illumination to an overall red color.

This change would happen suddenly, upon the 600EX-RT sensing enough internal heat. 

With the updated Speedlite 600EX II-RT, a sophisticated algorithm now means that as internal heat is detected from repeated, high-volume shooting, the speedlite progressively lengthens flash recycle time between shots in stages, making subtle adjustments that don’t suddenly hit the photographer as he or she is trying to rapidly cover a critical moment at an event or in the studio.  This progressively lengthens flash recycle time up to four seconds. 

If heat continues to build within the flash (from continued repeated, high-volume shooting, and/or from external environmental heat), the unit will eventually enter Level 1 (and again, slow recycle time to 8 seconds, and display LCD monitor warnings)… but it now takes longer to reach this stage with the 600EX II-RT, and heat-protection occurs in a more subtle, less-intrusive fashion.

These changes are especially important for high-volume flash shooters who work with external power supplies, which by definition tend to reduce flash recycle time, and encourage both faster shooting, and more total shots.


Included accessories with Speedlite 600EX II-RT

Several new accessories now come packed in the box with the Speedlite 600EX II-RT.  And, one of these is a noticeably larger flash case, to hold not only the speedlite and its mini-stand for slave unit operation, but all the new accessories listed below:

•     Light amber Hard Color Filter  (SCF-E30R1)

•     Deep amber Hard Color Filter  (SCF-E30R2)

•     Flash diffuser — Bounce Adapter SBA-E3

speedlite 600EZ II-RT case

Speedlite 600EX II-RT comes with a new, larger case. This case holds all included accessories, with separate pockets for the flash head accessories, the mini-stand, and the speedlite itself.


Amber filter

New hard amber filters attach directly to the front of the Speedlite 600EX II-RT, for white balance adjustment of flash illumination. Both a dark amber filter (shown here) and light amber filter are included. The dark amber filter changes flash illumination to approximately 3200K color, to match that of typical tungsten illumination when shooting on location. The light amber filter is useful in situations where flash is a primary source of light, to slightly warm-up the otherwise blue cast speedlite illumination often has. Please note that these filters, and the Bounce Adapter (diffuser), cannot be attached to the previous Speedlite 600EX-RT or other Canon speedlites.


bounce adapter attached to flash head

The included Bounce Adapter functions very similarly to popular third-party diffuser attachments often used with previous EOS speedlites. It’s included with the 600EX II-RT, and attaches directly to the flash head, secured with two projections that lock into slots on the bottom of the flash head. When attached, the flash head on the Speedlite 600EX II-RT automatically zooms to a dedicated “bounce adapter” coverage setting, to optimize even light distribution — even if the flash had previously been set to manual flash head zoom control. Again, please note that this diffuser is dedicated to the Speedlite 600EX II-RT, and will not attach to the previous 600EX-RT or other Canon speedlites.


Important:  because of changes in the flash head design, these filters (which attach directly to the Speedlite 600EX II-RT) will not attach to the previous 600EX-RT (or other Canon speedlites).  While it might be theoretically possible to place them on the flash head of previous Canon flashes and secure them with gaffer tape or something similar, Canon officially lists these new filters and the Bounce Adapter as not compatible with any speedlites other than the 600EX II-RT, as of mid-2016.

Similarly, the previous gel holder and gel filter system used for white balance adjustment with the original Speedlite 600EX-RT are not compatible with the updated Speedlite 600EX II-RT.

On the plus side, two cool points about the new filter system:  the bounce adapter can be combined with either of the included amber color filters, and they all attach in such a way that light leakage from the sides of the flash head is essentially eliminated — often difficult to achieve with gel filters over the flash.


Changes in Speedlite Custom Functions and Personal Functions

There are a number of changes in the built-in Custom Functions and Personal Functions with the Speedlite 600EX II-RT, compared to its predecessor.  Among them:

•     C.Fn 06  (Quick Flash with continuous shooting)
This Custom Function is removed from the 600EX II-RT — operation changed so that Quick Flash is active by default when camera’s Drive mode is on “continuous” as well as single-frame advance.  Adjustment now moved to Personal Function P.Fn 05 to turn Quick Flash off — this on–off control applies to all Quick Flash operation, in single-frame advance as well as continuous.

•     C.Fn 07  (Test firing power level in E-TTL when pilot lamp button pressed)
This is removed from 600EX II-RT;  if a test flash is fired in E-TTL, it always fires at 1/32 power level… to get a full-power test flash, temporarily switch to Manual flash mode, with power level at full 1/1 setting.

•     C.Fn 09  (Auto zoom for sensor size)
This is removed from 600EX II-RT. 

•     C.Fn 13  (Flash exposure adjustment by turning only the rear Select Dial)
This one has a welcome new addition, for user convenience:  if C.Fn 13–1 is active (flash adjustment by turning speedlite’s Select Dial only), it allows changes in both E-TTL flash exposure compensation, and Manual flash power level.  With previous 600EX-RT, adjustment of Manual power still required pushing a “+/-“ button on the flash, then turning the Select Dial.

•     P.Fn 05 changed — now (Quick Flash operation — on/off)
Personal Function 05 has been changed, so that this numbered function now allows Speedlite 600EX II-RT users to turn off Quick Flash operation (Quick Flash allows the speedlite to fire during the recycle period — ready-light is green, rather than red — before flash is fully recycled.  This makes it possible to capture quick moments that may occur with nearby subjects in E-TTL).

With previous 600EX-RT, P.Fn 05 turned automatic detection of Canon color filters for flash off if user desired… this feature is deleted from updated 600EX II-RT, since color filter detection is mechanically activated when either of the hard color filters is attached.

•     P.Fn 06 changed — now Flash firing during Linked Shot operation
This is the same as P.Fn 07 on the previous Speedlite 600EX-RT.  During Linked Shot operation, flash firing of a shoe-mounted speedlite is normally disabled (although a flash or transmitter is required to receive a signal and fire a “slave camera”).  With P.Fn 06 active on the 600EX II-RT, the flash will fire during exposure on “master” or “slave” cameras.

The Wireless button toggle sequence, previously P.Fn 06 on the 600EX-RT, has been removed, since operation is now a much more streamlined dial-based selection on the speedlite.

•     P.Fn 07 is deleted  (Linked Shot operation moved to P.Fn 06)

Speedlite Custom Functions can still be accessed and changed or adjusted either using the controls on the 600EX II-RT, or with the External Flash Control menu on compatible Canon EOS digital SLRs (see the previous list of “2012 and later models” for which cameras allow flash C.Fn control via the camera’s menu screen).

As with the previous 600EX-RT, to access or adjust Speedlite Personal Functions on the 600EX II-RT, you will need to directly access them on the flash’s LCD panel… even with the most recent EOS D-SLRs, their External Flash Control menu won’t display speedlite Personal Functions.



In what is clearly an evolutionary new product, Canon engineers have taken a truly significant existing product — the Speedlite 600EX-RT — and refined its operation and enhanced its reliability under demanding conditions.  The 600EX II-RT retains essentially all of the outstanding radio-based wireless flash capabilities of its predecessor, and can be immediately added to any existing speedlite system a Canon EOS shooter may currently use.  The new dedicated color filters for white balance and bounce adapter (diffuser) make this speedlite ready to roll for many location shooters, whether they work with a single flash on camera, or use their speedlites with any type of modifiers off-camera. 

Demanding shooters who want to leverage the rapid shooting speed of today’s EOS models will find this a willing companion, especially if teamed up with the new optional accessory Compact Battery Pack CP-E4N. 

Intuitive operation, excellent performance, integrated radio- and optical-based wireless E-TTL compatibility with nearly any EOS digital SLR,** and a new level of durability and heat-resistance.  Speedlite 600EX II-RT is a product we’re confident will strike a chord with many Canon EOS shooters, across a wide range of interests and experience levels.

** E-TTL automatic flash possible with all Canon EOS digital SLRs, except first-generation EOS-1D (4 million pixel version) and EOS-1Ds (11 million pixel version)