What is TTL in flash photography?

(Last Updated On: 26. May 2019)

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If you would like to shoot photos with a flash, you need to know your gear. Otherwise, it will happen that your pics look ugly and flat even with an expensive external flash. Luckily, there is a method beginners can use to train the skills in flash photography. This method is called TTL and in this blogpost I’ll give you some explanations about TTL. You will also get some information about the pros and the cons of TTL. In total, the whole topic TTL is about how much control of your camera you want, or how much control you want to give your device.

What is TTL and how does it work?

TTL means Through The Lens. This is a method a camera can determine, how much light a speedlight has to fire to expose the picture in the best way. Using the TTL method, there are two flashes are involved in every shot. First, the camera is “communicating” with the flash by sending out a pre-flash. Doing this, the camera discerns the information that it views through the lens, and then the actual flash is fired.

So the job of the pre-flash is to illuminate the field of view of the camera to provide what the camera needs: information about the brightness, colors, and so on. In other word, all that kind of stuff your camera needs to ascertain to tell the flash how to behave, or how much light the speedlite has to send out to the subject.

In this case it can be said that the camera and the flash have a kind of conversation if you will. The pre-flash pops out and the camera judges that. Then the camera sends a signal to the flash tellig it how much (or how less) light the flash has to fire.

On the picture below you can see the difference. I made these two pics with exact the same settings. But on the first one I used the manual adjustment. On the second one I let camera communicate with the flash.


Focal length: 58 mm
Aperture: f/9.0
ISO: 100
Speed: 1/160, tripod

E-TTL vs. i-TTL: Different terms for the same method?

TTL is a general term for a method of light evaluating. Therefore, terms E-TTL and i-TTL might seem a complete different things or at least, advanced methods. But actually these terms are just names given by manufacturers. It’s like the terms speedlight and speedlite (you might know it from my article about flash photography basics).

E-TTL is the name for a metering method developed by Canon and it means Evaluated Through The Lens.

i-TTL stands for Intelligent Through-The-Lens and it comes from Nikon.

Those two terms came up with the digital photography and since that time, the term TTL became slightly a generic term. There are surely technical metering differences between E-TTL (Canon) and i-TTL (Nikon). But in my opinion, it’s not really important for us who like to photograph and not to develop those devices, right?

So the only thing you need to know is that E-TTL and i-TTL are just different names for the same method (generally speaking). It’s important to know about this when you decide to buy speedlights from a third party manufacturer, like Metz* or Yongnuo*. You need to look exactly for which manufacturer the flash was produced.

TTL vs. manual usage of the flash

As the TTL method makes the usage of flash so easy, it can be assumed that’s the best way to make photos using a speedlight.

And indeed, for me, this is the biggest advantage of the TTL technology. Another advantage of the TTL method is that it’s a great opportunity for beginners to start using speedlites in photography and make their first steps within this discipline. For as a beginner, the manual mode could be pretty challenging and sometimes frustrating or disappointing. Using TTL, you would get the right approach, not only regarding the correct exposure but also consistent results while you shoot one scenery.

But here is the catch: you don’t always want a perfect lighted picture! Why? Because a perfectly lighted photo doesn’t always look great.

Light is one of the most important composition elements in photography. Especially, when you decide to make some emotional photos, you will need to work a lot with different lights to create an atmospheric mood. And this is not achievable with a perfect lighted photo!

When to use TTL?

As mentioned, one of the greatest benefits of TTL is the automatic metering of the environment and as a result, a correctly exposed photo. And that’s why TTL is very good for shootings in situations where you need to be quick. Therefore, it’s great for event situations, like a party, press events or other circumstances where you just need a sharp and correctly lighted photo without any creativity.

In situations where you want to be creative, the manual flash mode would be the better choice of flash photography. Using the manual mode, you have the full control of the light and can use it in the way which is best for your creativity. Therefore, using the manual mode would be rather for someone who already made the first experience with the TTL-mode.

Okay folks, this was a brief overview about the TTL method. Now it’s your turn. Get your TTL flash*, grab your DSLR* and start to practice. Also read my article about flash basics, if you need some more information about photography tips.

*Affiliate link: when you click on this link, no additional costs would arise for you and the product or the service will not become more expensive. When you decide to buy the product or use the service, I’ll get a little benefit from the provider which I would reinvest to keep this blog alive.

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