If you dive into flash photography, it is said that manual flash is the only way to go. It offers full control over the amount of light. Although this is true, there are situations when TTL flash measurement is the better choice. I’m talking about on-camera flash photography.
Have you ever used on-camera flash? I’m not talking about the built-in flash, but a full-size flash with a unit that can rotate and tilt. If you did, how were the results? Were you using an on-camera flash as a last resort? Some refuse the use of a flash totally, calling themselves natural light photographers. I know a few personally, and I also know the reason why they refuse to use flash. They don’t know how to use it in the proper way.
Although flash can be used for many kinds of photography, like macro, sports, and nature, it is mostly for studio work. A studio offers full control over light and subject. You can also take your studio outside and combine ambient light with flash.
Using Flash for Studio and Outside
Studio and outside photography have one thing in common: the distance between the light source and the subject does not change. This means we can set the flash output at the required amount once and keep it there as long as the distance doesn’t change. Only when we change the light setup does a new flash exposure has to be done.
This all changes if the distance between subject and flash will be different for every shot. If we have to measure the flash exposure for every single shot, flash photography would become almost impossible. Weddings, receptions, and similar events are situations when this occurs. A fixed light setup is not possible, so we need to take the flash with us. Since we move through the room, the distance between the flash and the subject will never be the same twice. An automatic flash exposure measurement like TTL flash is the solution.
TTL Flash for Flexibility
If we put a flash onto the camera, TTL comes in handy. The system will measure the required amount of flash output every time right before the photo is taken. It fires off a pre-flash and measures the exposure through the lens; that's what TTL stands for. This way, the system knows exactly how much light is needed for a correct exposure.
The beauty of the system is its flexibility. You can choose whatever aperture or ISO you want within limits. You can also use any shutter speed you like, even beyond the flash synchronization, if you activate hi-speed sync. As long as the flash unit can deliver the required amount of light, your subject will have a proper exposure.
If the flash exposure isn’t to your liking, there is the flash equivalent for exposure compensation. This way, you can change the flash output by the desired amount of stops. The flash exposure value (FEV) allows you to correct any faulty flash output that is measured and set by the TTL system.
Although the exposure will be correct, it isn't flattering light. After all, you still have direct flash. So, you need to get better light. This is when flash technique comes in.
A Proper TTL Flash Technique Is Required
A photo will benefit from good light, always. If you use flash and strobes, you need to be sure this is the case as well. It basically means no direct flash, but from an angle. Unfortunately, there will be situations when you are forced to use direct light. But with the right technique, you can still create the best possible exposure.
Just a recap: if you use flash, it is imperative to know about the difference between ambient exposure and flash exposure. You need to dial in your ambient exposure first by setting the aperture, ISO, and shutter speed. Next, you dial in the amount of flash until your subject has a proper exposure. With TTL flash, this is done for you, but you might need to adjust with the flash exposure value (FEV setting). This way, you achieve the best possible balance between exposure of the subject and surroundings.
If you need to use direct flash, this is also the way to reduce the hideous flash look everyone hates. You will just add the required amount of fill light to highlight the subject. It’s not ideal, but you are no longer dependent on the available light.
A Better Way of Using On-Camera TTL Flash
What makes a good flash photo? Two things, basically. The first is a large light source to get soft light, the second is directional light. This is why studio strobes are often fitted with a large softbox and placed at an angle. It produces great shadows on the subject, creating depth.
You can achieve this with an on-camera flash by using the rotation and tilting of the flash head. Just turn the head towards a wall nearby and bounce the flash toward the subject. The wall will act as a large softbox, which often turns out to be bigger than the ones used in studios. At the same time, the light will hit the subject from an angle. In one simple act, you create soft and directional light.
Combine this with a proper ambient exposure and you end up with a photo that looks quite natural. In the ideal situation, you won't notice that flash was used.
Still, as long as the subject can see the flash itself, direct light will spill onto the subject. By adding a flag, you can prevent this spill light. The subject will only be lit by the directional light. If the wall you bounce off is colored in any way, a color cast can occur. In that case, you might want to forget about a flag. A bit of spill light can lift the color cast.
If you don’t have a wall for bouncing light, try to find something else. A window, a mirror, or even someone else who wears light clothing. Try to prevent bouncing the flash from the ceiling, because you end up with the risk of ugly shadows under the eyebrows, nose, and chin, unless the room you’re in is relatively small, so the light can fill the whole room.
Do You Use On-Camera Flash With TTL?
I’ve been using my on-camera flash for many years, always with the TTL system activated. There were times when it became difficult to get the best possible results and I had to rely on direct flash, especially in dark rooms, halls, and churches, when there was nothing to bounce the light off.
But with a good balance between ambient light and flash, I managed to get a good result. Thanks to the TTL system, I was flexible and fast enough to capture a lot of great moments.
But when I have time at hand, I do prefer to take the flash off camera and use it in manual mode. It’s using the technology that’s available when the situation asks for it. In the end, it's about getting the best possible result.