TTL flash lets the camera measure the scene and decide how much power the flash fires, while manual flash fires the same power every time until you change it. Use TTL when conditions change fast, and use manual when you want repeatable, consistent results.
How TTL Flash Works
TTL stands for through the lens. Before the main shot, the flash sends a short pre-flash, the camera measures how much light returns, and it calculates the power for the actual exposure. The flash and camera then work together without you setting the output.
- It adapts when your subject moves closer or farther away.
- It handles quick changes in distance and angle.
- It lets you adjust with flash exposure compensation, usually written as plus or minus stops.
Names and exact behavior differ between camera makers, so check your flash manual.
How Manual Flash Works
In manual mode you choose the power directly, such as full, half, one quarter and so on. The flash does not use a pre-flash to measure anything. If you keep the flash distance, the aperture and the power the same, each frame gets the same amount of light.
Key Differences
| Trait | TTL | Manual |
|---|---|---|
| Power setting | Automatic | Set by you |
| Consistency | Can vary by scene color | Same every frame |
| Speed of use | Fast | Slower to set up |
| Learning curve | Easy | Moderate |
| Pre-flash | Yes | No |
When to Use Each Mode
Choose TTL for events, weddings, family gatherings and street work, where you move around and the distance to your subject keeps changing. Choose manual for studio portraits, product shots, multi-flash setups and anywhere the lighting should match from frame to frame. Manual is also useful when a pre-flash would make people blink or trigger other flashes early.
How to Move From TTL to Manual
- Set your camera to manual exposure and choose an aperture and shutter speed that suits the ambient light.
- Switch the flash to manual and begin at a mid power such as one quarter.
- Take a test frame and check the brightness on the screen.
- Raise or lower the flash power by one step at a time.
- Keep the distance steady, or adjust power when you move.
FAQ
Why does TTL give uneven results on white or dark subjects?
The system tries to make the scene medium bright, so very light or dark scenes can fool it. Flash exposure compensation usually corrects this.
Can I mix both modes?
Yes. Many systems let you put one flash on TTL as a fill and another on manual as the main light.
The Short Version
TTL is fast and forgiving when things move, and manual is steady and predictable when you control the setup. Learn both, and switch to manual when you need identical frames.
