When it comes to flash photography, there seems to be a constantly recurring question: manual or TTL flash? So at the end of the day, which one should you really be using?
Throughout Facebook groups and photography forums, you will see the same battle carried out over and over. Someone will ask if they should use manual or TTL flash when they are shooting. One user will come in and say “always shoot manual.” They will go on to explain that manual flash is the most consistent way to expose your image. When you use manual flash, you set your flash power and it will then use that same power for every exposure. But then, another user will chime in and say “TTL is the only way to go.” They will inform everyone that TTL is the fastest way to light an image. TTL uses a quick flash before the shutter is opened to know what the power of the flash should be and then automatically sets your flash to that power.
So who is right and who is wrong? Unfortunately, both are sort of right and both are sort of wrong. The real answer is, it depends on what you are shooting. Let me explain. Manual flash and TTL both have advantages and disadvantages depending on the situation. The key is to know when and where each one is at its greatest advantage.
Because manual flash is basically set it and forget it, this setting works best when you know exactly where your light will be, where your subject will be, and what your camera settings will be. Once you have your camera and flash power set, you can feel free to shoot as you please. You can get close, move far, change lenses (as long as your aperture does not change), etc. Your flash will consistently fire at the power you set and your subject will remain the same exposure.
The drawback to using manual is that, in general, there is a bit of a guessing game to figure out what your flash power should be. You set everything up, take a test shot, adjust flash power, and repeat until your flash is dialed in. I say “in general” because, with practice, it’s possible to get pretty good at knowing what power you need given different situations. But even then, it can still require some fine-tuning pretty often.
Another drawback is when you are dealing with situations where the distance from your subject to flash is unknown or constantly varying. Depending on your setup, even a one or two-foot change can cause a drastic change in exposure. So if your subject is moving through a scene and your light is stationary, the amount of light on your subject will constantly vary.
Where manual flash struggles with a varying subject to flash distance, TTL shines. Because the flash emits a quick burst of light to measure what the light power should be set to, it knows when the subject has moved a bit closer or further from the light. This is especially useful for event photography. If you are using direct flash and don't know how far or close your subject will be, TTL will get you close or spot on to a perfect exposure. Same for if you are roaming around a venue bouncing the flash off a wall or ceiling. As you move closer or further from a wall, that will require you to raise or lower your flash power, which TTL will do automatically.
The drawback here is that TTL is not perfect. It will get you pretty close, but the metering system is similar to the metering system on your camera. Throw in a subject with bright clothing and the flash will compensate by making the flash power lower than it needs to be. Give it a dark subject and the power will be too high. Similarly, If you have the light off camera and the light is perfect on your subject, even a small change in composition can change the output of your light.
So What Is the Answer?
In the case of event photography with on-camera or bounce flash, close is all you need. The power output that TTL calculates will normally be better than what you can guess. Even if you can guess just as close as TTL gets you, both will still require a bit of fine-tuning in post-processing. So in my opinion, might as well let the flash do the guesswork to save you some mental capacity so that you can concentrate on the moment and composition. If you are doing event photography and you know the subject to flash distance will remain constant (same height ceiling to bounce off of for example), then you might as well shoot manual and remove all the guessing.
For portrait work, I think that manual flash is the way to go. You will normally be dealing with a posed and staged situation where you will know exactly where your subject will be and where your light will be. So save yourself from having to deal with small variations in the light output you could get from using TTL. Where TTL could work well for portraits is when your subject is moving through a scene and that flash to subject distance is constantly changing. Although, it’s possible to get around this with some good direction to your subject and using the inverse square law to your advantage.
Manual Plus TTL
There are some flashes where you can use TTL to get you close, then when you switch to manual, the flash will remember that power output. This minimizes some of the work by letting TTL take care of the initial guess. If the guess is good, then switching to manual just locks in that power for you. If the guess is a bit off, switching to manual still locks in that power and then you can simply fine-tune your settings from there. This is great when starting out with flash because you may not have any idea where to start. So simply let TTL get you close, switch to manual, and then take it the rest of the way from there.
TTL is not better than manual or vice versa. They are simply tools that get you the results you are looking for depending on the situation. So when someone asks if they should use TTL or manual flash, the answer isn’t so simple. It depends on the situation and how they are shooting. Although manual flash can work for any situation, TTL has the ability to save you a lot of time and headache when used correctly. So if you understand both and how they work, then you will know what to use and when.
Are you “team TTL” or “team manual”? Or are you like me and think they are just different tools for different situations?