So whats new with Canons E-Ttl system? Well, here is a fast overview of some new features. If you don’t know much about E-Ttl you may want to check out an older post on the basic system as it was/and still is with all current and previous EX flashes. Click Here! If you want to see some quick examples of what can be done with speedlites Click Here!
So what has changed? Well, first you should know the 600EX-RT works with all previous EX flashes just as the 580EX2 did. It can be a master or slave and work with Canons optical wireless system as always. Now for whats new. First, the 600EX-RT and ST-E3 are a radio controlled system, (the ST-E3 is radio only, whereas the 600 can also communicate with the optical E-Ttl system) When working with the new radio system and newer body cameras (5D3, 1DX, 6D, T4i) You can control up to 15 600EX-RT lights in 5 groups. The radio signal is good in all directions for about 100 feet.
What else is new? Well, now the control you have over the groups has been expanded. 1st, you can set individual groups to be either E-Ttl or Manual simultaneously. Why would you want that? well, lets say you have certain lights on the background, or room lights, once you set the exposure for a given aperture those lights need never change power, and there is no need to use E-Ttl to set them again in that situation. So you can have the main lights and hair or rim lights on E-Ttl while the background or accent lights are set to manual. In manual, the speedlites have control from full power to 1/128th power, that is easily changed through the camera menu (as long as you have a ST-E3 or 600EX-RT on the camera), or you can use the ST-E3 or a master 600EX-RT controls directly. You also have a flash ready light visible on the main that reports when slave units are ready to fire (recycled)
What else? Well rather than the older A:B ratio you have full control of each group. The older system had 3 groups and you had individual control in manual, but in E-Ttl you had A:B ratio from 8:1-1:8 and C was a plus or minus 3 stop range adjustment. Now you can set each group to plus or minus 3 stops in E-Ttl, and combine that with some groups in manual if you choose.
Also, you can turn off a group, something you could not do from the camera before.
So now you have groups A, B, C, D, E, and they can be used in E-Ttl or manual or turned off from the camera position. All can work in High speed sync, rear curtain sync and multi mode.
You still have an overall plus and minus 3 stop flash exposure compensation that effects all groups in E-Ttl mode. You still have flash bracketing, and flash exposure lock, as well as a modeling light function.
If you have an older body or want to mix in an older EX series flash (580, 580II, 550, 430, 420) you can using the optical system and the older 3 group system with ratios. And if using the radio system (ST-E3, 600EX-RT) you revert to the older 3 group with ratio system. Read more about that system here Canon E-Ttl System
Another new feature, not directly E-Ttl control related on the 600EX-RT is the new gel holder and the flashes ability to set the auto whitebalance for the use of color correcting gels in use. Its a nice new feature that used to be manually, is it the reason to buy the new system, no, but its a great thing to have available, I know, I use gels on most all my flashes, so it was a nice addition to have.
Linked shooting is also new. You can connect the flash to the camera via hotshoe (newer bodies) or with a Canon cable and fire remote cameras. This is very useful when you have several camera angles to cover and no other shooters. You can set one master to fire the other camera bodies and have their flash either firing or not. This can work with the 600, and ST-E3.
So the big question: Should you upgrade? I would say Yes, but I am aware that money is often a factor, I would strongly suggest that any new flash purchase you consider should be investing in the new radio system. If you have an older body and cannot take advantage of the newer 5 group system, you can still use the 600’s with your current gear and will be building toward the day you upgrade your body. If you get a ST-E3 and 600 you can use the radio feature in the old 3 group system until you get an upgraded body and if you have many older EX flashes you can still use the 600’s with them and again be building toward the future when you go radio and gain access to all 5 groupings. Is there a downside to the new system? well, I see one, but not many will care or ever notice, and that is the fact that the new system is limited to 15 total speedlites, where as the older system was not limited to total number of lights used, this is not the groups, but the actual number of lights that will be controlled in any or all groups. If you will often be using more than 15 lights you have some options, use the older system, use the newer system along with manually controlled (not through the camera but through a pc sync (likely to a radio transmitter) connection that is not figured into the E-Ttl exposure or able to be controlled from the camera directly, or go all radio without using the canon system (all Pocket Wizards or similar, as you would with strobes or non dedicated flashes) Truthfully, while it is a limitation, its an easy workaround, and one that I think anyone who would be using 16plus lights will have no issue figuring out .
None of this is to say there is anything wrong with the older system, it has been working well for years and produces great work as it always has, and will continue to do so for many, many years to come, but the newer system offers many advantages. Not everyone will need, want or take advantage of the new features, so you have to decide if its worth the upgrade to you, but I can say that having more choices has rarely ever stopped me from being happy, it may have made things take longer to do while I was playing with all those features, but that’s more me being a gadget freak than anything else. 😀
Another note, some have asked why not use the older EX flashes with a radio trigger, and I will tell you I have and do still use them (I am currently using a Yongnuo 622c radio system on the older speedlites) but the range is growing, I can name the Pocket Wizard TT5 and Mini, the Radio Poppers, Pixel King has several versions. All those mentioned can wirelessly control your off camera E-Ttl system and have slight variations on the original 3 group theme. The difference is in the newer 5 group system, to move up to controlling 5 groups independently the only current system I know for the Canon is Canons own. That may or may not be the deal breaker for you, but look into what the other radios offer and compare directly, they work, some great some soso, but they are not as advanced as the current Canon system.
To Learn more Check out some of my workshops here, or look into some of the great workshops that Canon puts on at http://www.learn.usa.canon.com/live_learning/workshop_main.shtml