Modern photography is full of fantastic equipment that can be used in many ways, but having the equipment is meaningless if you do not know how to use it well. This means that understanding the differences between ETTL and TTL systems is critical for everyone who takes photography seriously, be professionally or as a hobby.
ETTL and TTL are flash metering systems to determine exposure when taking a photo. TTL activates the flash and closes it only when the sensor receives enough light. ETTL executes a pre-flash to determine the required light and adjusts the main flash accordingly.
Knowing the difference between ETTL and TTL can mean the difference between a great photo and a mediocre one. It is essential to understand these flash metering system types and how to use them to get the most from your gear. Let’s explore ETTL and TTL to identify their differences and when to use which system.
What Is The Difference Between TTL and ETTL?
An external flash is considered essential equipment for many photographers. The type of flash you use and how the flash interreacts with your camera determines how effective it is, how easy it is to use, and how the flash affects your shot.
If you want softer light from that setup, a flash diffuser can help shape the result.
ETTL and TTL are both camera flash metering systems used for Canon cameras that integrate with the camera to change the flash parameters and how the camera uses the flash for a photograph.
Understanding the differences between ETTL and LTT flash metering systems is essential to get the most from your gear and use these flash types to your advantage.
Let’s explore what these systems are to better compare them and identify their essential differences.
TTL Flash Metering System
TTL stands for “Through The Lens.” This flash metering system is among the oldest and was initially developed for film cameras.
A basic description of how this system works is that when this type of metering system is used with flash photography, the camera initiates the flash at full brightness and measures the amount of light brought in through the sensor.
When the camera receives enough light for a full exposure for the required photograph, it turns the flash off.
This system uses the same flash intensity regardless of the scene being photographed and the ambient light in the area; it only adjusts the length of time that the flash is active based on the amount of exposure the camera requires to capture the image.
TTL cannot adjust the flash level according to reflective surfaces in the scene and always uses the same flash brightness. This brightness can sometimes be changed, but it is usually set to the maximum brightness of the flash.
TTL for film and digital cameras works slightly differently, but it is essentially the same process.
ETTL Flash Metering System
ETTL, sometimes written as E-TTL, stands for “Evaluative Through The Lens.”
This flash metering system allows the camera to engage the flash and release a pre-determined amount of light into the scene. This is called the “pre-flash.”
The camera then calculates how much light the sensor received during the pre-flash, where the focal point of the lens is, and the amount of light required to capture a full exposure.
The flash is then adjusted based on the calculations made by the camera, and a second flash is released to take the photo.
This system enables the camera to adjust the brightness the flash uses and the length of time that the flash is active. The camera can make the necessary calculations with this system so quickly that the total time required for the pre-flash and the main flash is so short that they are indistinguishable from each other and appear to the eye as a single flash.
ETTL is a very accurate flash system and allows modern cameras to very accurately determine how much light they require to fully expose a particular photograph.
Cannon has released a system called E-TTL II, which is essentially the same process as standard ETTL, but it has an upgraded calculation system and better sensors for more accurate light metering.
What’s The Difference?
Now that we have explored these flash metering systems more deeply, we can accurately assess their differences.
The difference between ETTL and TTL is that the ETTL metering system pre-exposes the scene to a known amount of light and adjusts the brightness and length of the flash according to what the camera requires.
TTL, however, fully opens the flash to full brightness, providing light for the camera sensor, and turns the flash off when the sensor has received enough light to capture the image.
Which Flash Meting System Is Better?
Both flash meting systems are useful, and they are both still used on cameras today. However, there are some significant advantages to ETTL over TTL.
Most photographers prefer using ETTL over TTL, as this metering system provides superior control over the flash and how it can be used.
TTL is more difficult to use, as it is very easy to over-expose a shot, and it is very difficult to control how the flash affects the scene.
ETTL also has systems built into it to ignore reflective surfaces in the scene, while TTL does not. This means that ETTL accounts for external light sources far better than TTL and usually produces a more reliable result than TTL.
Most photographers agree that ETTL is better than TTL, but there are still uses in the photography industry for TTL flash metering systems; they only need to be used correctly.
Conclusion
ETTL and TTL are both useful in their own right, but ETTL is more useful on a day-to-day basis. ETTL is easier to use, more effective, more controllable, and usually yields a better image with more consistency.
Be sure that you understand which flash metering system you are using, and learn everything you can about it to get the most from it. It is not wrong to use TTL or ETTL over the other, but you must understand when to use them to get the best shot with these systems.