Have you tried out slow sync flash yet? If your flash has been at the bottom of your camera bag or in the cupboard for a long time, you should get it out and have a play with 1st and 2nd curtain sync flash. It’s a really creative photography technique that can produce some very interesting images. The look you can achieve can be like an extended exposure, but with a few extra bits of magic that can make an image really look different from the norm.
Using this technique you can create effects that combine motion blur, together with the frozen motion you get when using flash.
There are two ways to use slow sync flash mode. You can have the flash fire at the beginning of the long exposure, or you can have it fire at the end. Whenever you hear someone talking about 1st curtain and 2nd curtain flash modes, this is what they’re referring to. Depending on the shot, one might look better than another.
Here are two examples of different flash techniques.
Why is the process called 1st and 2nd curtain? The process has to do with the way the SLR shutter mechanism works and is built. Your DSLR cameras shutter is composed of two shutters, one that opens at the beginning of the shot and another that opens at the end of the shot. Every time your camera takes a picture, the first curtain opens to start the exposure, and the second curtain closes to end the exposure. This is how it’s possible to get shutter speeds as fast as 1/1000s and above. It’s really two separate mechanisms firing on their own.
So, when we talk about 1st curtain flash and 2nd curtain flash, we mean the curtain that triggers the flash. If you’re using 1st curtain flash mode, the flash will trigger after the first curtain opens the shutter. In other words, it will trigger at the beginning of the exposure. If you’re using 2nd curtain flash mode, the flash will trigger just before the second curtain closes the shutter. That happens right at the end of the exposure.
Which type of should you use, 1st or 2nd sync flash? It all depends on the effect you’re trying to create, but the best tip I can provide is experiment with both types; try also panning with your camera too. You will need to practice before you start to get images that will look good and like everything it takes time and practice and I am still learning and improving this technique myself.