The difference between E-TTL & TTL for Canon flash
E-TTL flash
Canon’s DSLR cameras use a pre flash to determine the correct flash exposure, a system known as E-TTL. Way back in time, Canon EOS film cameras used a system called TTL flash where the flash was metered off the film surface during the actual exposure.
Several of the Speedlite EX series of flashes are possible to be configured for either kind of flash metering system. By default Speedlite EX series flashes are set to E-TTL, but a custom function allows them to be changed to the older TTL system.
How to spot E-TTL and TTL
Same flash, but C.Fn 05 determines E-TTL or TTL operation
If you’ve been messing with the flash custom functions (C.Fn) then it’s possible to set your flash to TTL, then on most DSLR cameras you get a lot of trouble. Fortunately the LCD display on the flash shows different indications, ETTL for ETTL mode and TTL for TTL mode – kind of obvious.
If you incorrectly set TTL mode; the flash will fire at full power all the time, or not fire at all. You also won’t be able to set wireless flash operation.
The problem is that when the error is relayed via the internet the E is often left out of the ETTL and so TTL and E-TTL become interchangeable in a discussion but they are not interchangeable in use.
So why does this function even exist?
It’s to do with compatibility; Canon DSLR cameras only have E-TTL metering, some* of the film cameras have E-TTL and TTL to allow them to be used with either more recent flashes or older ones. Older Canon flashes from before the Speedlite EX series only provide TTL flash, not E-TTL.
* Film cameras with both E-TTL and TTL flash capability – EOS-1 V, EOS 3000, EOS 300, EOS 30, EOS 33, EOS 3000N, EOS 3, EOS IX 7, EOS IX, EOS 500N, EOS 50, EOS 50E
E-TTL / TTL confusion solved
If you have a Canon DSLR NEVER set C.Fn 05 to 1 on your Speedlite 600EX-RT, 580EX II or MR-14EX II
[tweet this]If you have a Canon DSLR NEVER set C.Fn 03 to 1 on your Speedlite 580EX, 550EX, MR-14EX or MT24-EX
Canon Speedlite flashes that can be set to TTL mode
- Speedlite 600EX-RT – via C.Fn 05, 0 = E-TTL, 1 = TTL
- Speedlite 580EX II – via C.Fn 05, 0 = E-TTL, 1 = TTL
- Speedlite 580EX – via C.Fn 03, 0 = E-TTL, 1 = TTL
- Speedlite 550EX – via C.Fn 03, 0 = E-TTL, 1 = TTL
- Macro Twin Lite MT-24EX – via C.Fn 03, 0 = E-TTL, 1 = TTL
- Macro Ring Lite MR-14EX II – via C.Fn 05, 0 = E-TTL, 1 = TTL
- Macro Ring Lite MR-14EX – via C.Fn 03, 0 = E-TTL, 1 = TTL
External Auto Metering & External Manual Metering
Most photographers would not venture in to C.Fn 05 / 03, but with the release of the Speedlite 580EX II Canon added External Auto and External Manual metering modes – kind of like the old thyristor metering in old flashes.
Canon opted for C.Fn 05 to have four possible values and so some people may be confused when switching back from the External metered modes as to which is the right mode TTL or E-TTL.
Find out more about external flash metering…
Many thanks to Devon based photographer Scot Baston for asking the question that gave me the content to write this post. Scot further added the complexity of Pocket Wizard TT5 and a Sekonic L-478DR meter to the problem. It should have been possible for Scot to set the power of a flash directly from the Sekonic meter, but with the Speedlite 580EX II having C.Fn 05 set to 1, it never could.
More fantastic information Brian. You’re such a wealth of knowledge and you’re very generous in sharing it. You’ve helped me in so many ways – including opening up a whole new ‘Speedlite world’ to me – thank you!
Jules
Thanks for the kind comment Julia, glad that the Speedlite world is less of a scary place for you nowadays.
Brian / p4pictures
I’ve not yet run into this issue which says, I don’t use my flash enough 😉
It’s a good tip to have in the back of my noggin if this occurs.
Cheers
JT
Jonathan I think the phrase is “messing with the custom functions” combined with not reading the manual [NRTM].
Brian / p4pictures
they have manuals??
Brian, I have accidentally set my flash (430EX II) to TTL and am trying to get it back to ETTL mode. Can you please help me? Thank you so much in advance, Aimee
Hi Aimee,
It’s a challenge to accidentally set the 430EX II to TTL instead of E-TTL. Basically the flash detects the type of camera and for older ones it shows TTL, for newer ones it’s ETTL. When I say older cameras I’m talking film-era EOS.
What camera are you using it with?
Brian / p4pictures
Hi Brian,
I have the same problem. I have a Speedlite 600EX-RT on a Canon 70D.
I have wiped down the connections, so hopefully it wasn’t that.
It has worked on ETTL for a couple of years.
Many thanks
Tracy
You saved my bacon!!! My granddaughter has asked me to photo her prom date and several other couples this evening, and it is over-cast, so I’m going to need the flash as back-up and I remember since I war experimenting with it, it got possessed by demons, high on full power, totally uncontrollable, and in TTL not ETTL. Panic was setting in as I have to leave in minutes, out of desperation I searched and found you. cf 5 on my 580-ex-II was the culprit. Thank You !!! got to run
Hello Brian Worley
I went to buy my first flash Yesterday at Best Buy, but I am very confuse
and I didnt because I don’t know if the 430 is the correct one and the guys in there dont know nothing about nothing
please can you help me?
I bought last month camera Canon 80 D
Thank you so much
Hi Eunice,
The Speedlite 430EX III-RT would be a great match for your EOS 80D. You can use it on the camera hotshoe, set to E-TTL for simple automatic flash with more power than the cameras’s built-in flash. You can move the flash head to bounce the light from a ceiling or wall for more flattering results.
When you’re ready you can use the flash off-camera set to optical receiver (slave) mode and configure your EOS 80D built-in flash to control it. IF you get really in to off-camera flash and want to work in brighter sunlight – where the optical system is not so good – you could add a ratio trigger such as the Speedlite Transmitter ST-E3-RT.
Hope this helps.
Brian/p4pictures
Hi Brian, I have a Cannon EOS 7D, which ETTL Speedlite would you recommend. I don’t really want to pay more than 200AUD
Hi Issy,
For 200AUD then you might want to take a look at the Yongnuo YN600EX-RT II flash. It’s $169 on Amazon Australia.
It’s a clone of the Canon 600EX-RT but not weather sealed, and the build is cheaper quality. But it’s a lot of flash functions for the money and does work with the Canon radio flash units if you need it to later.
Brian / p4pictures
Thanks, I recently bought a Canon EOS A2 to shoot B&W film, and had wondered if my 430 EXiii-RT was compatible. Thanks to your answers to others I see that the answer is Yes.. Many Thanks, Richard
Hi Brian. Please help. I have a Canon 100d.. I want a ttl speed light however not sure if it would be ettl or ttl . And what speed lights would you recommend? So confused, I know the type of photo I’m trying to achieve but minefield getting the right equipment.. Please can you simplify things for me with my make of camera x
Hi Amy,
E-TTL is Canon’s acronym, meaning evaluative through the lens. TTL is the generic through the lens abbreviation. Your EOS 100D can work with any Canon Speedlite flash with the letters EX in the name. When on the camera, the flash will show E-TTL in its LCD display.
Given the compact size and weight of the EOS 100D I’d avoid a big Speedlite as it makes the camera somewhat top heavy. The most obvious Canon Speedlite is the 430EX III-RT, though several other older versions also work fine, including Speedlite 430EX, Speedlite 430EX II or slightly lighter Speedlite 320EX.
Hope that helps,
Brian/p4pictures
Brian,
I have a Canon 430EXIII-RT speedlite. My camera is a Canon 5D Mark IV.
I’d like to use my speedlite remotely. In order to do this I understand I need a transmitter…
I was advised by someone that I should buy the GODOX Thinklite TTL TT685C Camera Flash 2.4GHz High Speed 1/8000s GN60 for Canon EOS DSLR E-TTL II Autoflash (TT685C) and the Godox Xpro-C TTL Wireless Flash Trigger for Canon 1/8000s HSS TTL-Convert-Manual Function Large Screen Slanted Design 5 Dedicated Group Buttons 11 Customizable Functions. I would love to know what your thoughts is on this before I buy something that I might regret. Please help me understand if this is a wise choice other than price. Thank you so much. As you can probably see I don’t know much of anything about external flashes.
Hi Lisa,
You only need a transmitter as your 430EX III-RT includes a radio and optical receiver inside. The Canon option for a radio transmitter to go on the cameras is the Speedlite Transmitter ST-E3-RT. You could also use a Speedlite EL-100 as the optical transmitter on your camera. From the independent makers, try looking at the Yongnuo YN-E3-RT II as a lower cost version of the Canon ST-E3-RT transmitter.
Brian / p4pictures
Hi Brian,
I’d like to continue on this topic of remote use of a flash.
I have the Canon 100D. I’d like to buy Yongnuo transmitter and flash that support ETTL. I wonder if the Yongnuo YN 560II TX transmitter and the Yongnuo YN-685EX flash would work together with my camera. What is your opinion on such a system?
Hi Peter,
I don’t have experience of the Yongnuo YN 560II TX transmitter, but when I searched for information it appears to only provide manual flash operation, not E-TTL. I think you’ll need the YN-622C TX to be able to do E-TTL flash.
Hope that helps,
Brian/p4pictures
Hi Brian. Greetings for the new year.Recently acquired the MTT1 and the MTT5.for the canon 60D.and 580EX.following instructions ETTL shows on the window and then changes to TTL from then on the flash only fires on the test button External flash C.F setting External flash C.Fn stting flash power is tutned off !!
Please help
Chers
Peter
I forgot to mention I’m using a Canon 5D Mark II and have been using that camera with these flashes for a few years now so it’s not an old camera. Thanks!
Hi Brian I’m so pleased I stumbled upon you & this discussion. I bought a 2nd hand 580exll a few years ago to use on my 6DMK2 but I could never get ETTL on it only TTL. I seldom used it except on Multi mode but it was very hit & miss. I’ve recently purchased an R6 & decided to give the flash another try & found this post & have changed Cfnc5 from 1 to 0 & I now have ETTL set on the flash & instead of nothing but blown out shots I now have control over what I’m doing. I’ve still got so much to learn but I’ll now be taking my flash on holidays to Canada & Alaska in 9 days time. Cheers. Steve
E-TTL vs. TTL: Clarity Is Key!
This post is such a gem for clearing up the confusion between E-TTL and TTL flash systems, especially for Canon users. It’s amazing how something as simple as the omission of “E” in discussions can lead to so much miscommunication and frustration for photographers.
Your explanation of the historical context—TTL being for film cameras and E-TTL for modern DSLRs—really ties everything together. It’s also great that you included specific examples of compatible cameras and the custom functions for different Speedlite models. Those details will be lifesavers for anyone troubleshooting their flash settings!
The warning about never setting C.Fn 05 (or C.Fn 03) to TTL on DSLR-compatible Speedlites is critical. I can imagine this saves countless photographers from hours of confusion and troubleshooting.
Quick question: Would you recommend external metering modes (like the External Auto Metering) for specific types of shoots? It seems like a powerful option but might be daunting for less experienced users.
Thanks for taking the time to break this down so thoroughly! It’s an invaluable resource for Canon users navigating the world of Speedlites.