The 60D has two flash synchronization modes: first curtain and second curtain. The term curtain relates to the opening and closing of the shutter—the first curtain refers to when the shutter is being opened, and the second curtain describes the point just before the shutter is closed (try to visualize a curtain on a stage opening and closing; the amount of time it’s opened is how long your shutter speed is).
FLASH SYNC
The basic idea behind the term flash synchronization (flash sync for short) is that when you take a photograph using the flash, the camera needs to ensure that the shutter is fully open at the time that the flash goes off. This is not an issue if you are using a long shutter speed such as 1/15 of a second, but it becomes more critical for fast shutter speeds. To ensure that the flash and shutter are synchronized so that the flash is going off while the shutter is open, the 60D implements a top sync speed of 1/250 of a second. This means that when you are using the flash, your shutter speed cannot be any faster than 1/250. If you used a faster shutter speed, the shutter would actually start closing before the flash fired, causing a black area to appear in the frame where the light from the flash was blocked.
The built-in flash on your camera can be synchronized to fire during the first curtain or the second curtain. This only applies to shutter speeds of 1/30 of a second or slower, since a faster shutter speed moves so quickly that the mode wouldn’t really matter. But for longer exposures, I find that using the second curtain flash is usually the best option.
For example, imagine you are photographing a person running (let’s say from left to right) in a race. It’s somewhat dark outside, maybe at sunset, so you can get away with a slower shutter speed of 1/15 of a second, but you also want to use your flash to freeze the subject in place. If you take their photo in 1st Curtain Sync mode, the flash will fire right away, and the person will run across the frame during the rest of the exposure. Because you used a slower shutter speed, you will see blur in front of the runner, as the flash froze them in place at the beginning of the exposure. If you change your flash setting to 2nd Curtain Sync and take the same photograph, you’ll see some blur across the frame after you press the Shutter button, but the flash will fire at the end of the exposure, making the blur appear behind the runner.
SETTING 2ND CURTAIN SYNC
- Press the Menu button and use the Main dial to navigate to the first camera setup menu tab, select Flash Control, and press Set.
- Use the Quick Control dial to select the Built-in flash func. setting, and then press the Set button (A).
- Use the Quick Control dial to select Shutter Sync., press Set, and select 2nd Curtain (B).
Now, when you are using a slow shutter speed (slower than 1/30 of a second), once you press the shutter, you’ll notice a quick burst of light from the flash to measure exposure, then the full burst at the end of the exposure to light your subject.