In this tutorial from the Intermediate Flash Photography course, we're going to be talking about how to use a slow shutter speed and a flash to get really cool images like this:
How to Freeze an Image With Flash
One of the first things that most photographers learn is that in order to get sharp photos with no motion blur, you have to use a shutter speed that is high enough to freeze the motion in the scene.
For natural light photographers, this is just a limitation they have to live with. The cool thing about flash photography is that the extremely short duration of the flash allows us to freeze action, even with a slow shutter speed. In fact, you can get a sharp photo of a moving person with a 30-second shutter speed.
Camera Shake vs. Motion Blur
In order to create images in this way, there are a few basic things that we have to understand. The first is the difference between motion blur from camera shake and motion blur from the subject matter.
In the photo above, the car is blurry because it moved through the scene during a long exposure.
In this next image, the camera is now handheld.
The blur we are seeing this time is coming from camera movement. You can usually identify this kind of motion blur by the fact that the whole scene is blurry.
If we get crazy with a really slow shutter speed or really fast camera movement, we can get pretty exaggerated motion blur from camera shake.
First Curtain Sync vs. Second Curtain Sync
The other thing to understand is the difference between a first curtain flash sync and a second curtain or slow sync flash.
First curtain sync is the default mode for most cameras and flashes, and it works something like this. When you take a photo with a shutter speed of 3 seconds, the camera and the flash work together to sync the firing of the flash with the opening of your shutter. Once the shutter is fully open, the flash fires. The amount of time that the flash is producing light is about 1/10000th of a second. After that, the shutter just sits open, collecting ambient light for the rest of the 2.99 seconds, until the shutter closes.
For the same photo with second curtain sync, the only difference is that the shutter would open first and begin taking in ambient light for 2.99 seconds. Then, at the end, just before the shutter closes, the flash would fire.
3 Ways to Freeze an Image With Flash
So with those two tools in our belt, let's see how we can use them to get creative and make some really awesome photos.
There are three ways that I generally use a slow shutter and flash together.
1. Still Camera and Still Subject
The first and most straightforward way I use them together is with a still camera and a pretty still subject. Even a person trying to be still is going to move a little bit and cause motion blur. But, by using a flash with a very short duration, we can freeze our subject and eliminate that motion blur.
I start by placing my camera on a tripod, which will hold the camera steady during the long exposure and eliminate any motion blur from camera shake. Next, we need to set the camera aperture, shutter speed, and ISO to capture the ambient light the way that we want it. Then we set our flash power to the correct level to illuminate our subject. Because everything is pretty much still, it doesn't matter if you use first or second curtain sync. It's when we introduce some motion to our scene that the fun really begins and you'll want to use second curtain sync.
Here's an example of an image taken in that way.
2. Still Camera and Moving Subject
In our next example, we're going to keep the camera locked down with the tripod, just like in the last image, but now our subject is going to be moving, and there's going to be a bit of ambient light hitting our subject as well.
In this first image, there's no flash, just a slow shutter speed.
As you can see, we get a great sense of motion, but the subject is blurred and it's hard to see what's going on. In order to get our subject to pop, we can add a flash.
In this next image, you can see that the flash has really cleared things up.
However, there's still something not quite right about this image, and that is that the action looks backwards. That's because we used first curtain sync, which lit up the subject at the beginning of the action, instead of at the end of the action.
Here's what it looks like when we change to a second curtain sync.
We get pretty much the same results, except now the action looks correct and pleasing, because the blur leads to the subject instead of away from the subject.
3. Moving Camera and Moving Subject
The third, and most common way that I use this technique, is to use both subject motion and camera motion to really bring the viewer into a scene and give them the feeling that they are there. I use this technique to shoot the dancing during a wedding reception because of its ability to make the motion and the emotion really shine during the party. Here are a few examples of what this can look like.
This is also a fun way to shoot a reception because the best results come from you setting your camera and then going out on the dance floor and dancing while you take photos. Since you're dancing along with your subjects, the photos really replicate what it was like to dance to that song on that night, and helps people feel what it was like to be there.
As you can see, there is so much you can do with slow shutter speed and a flash. There are so many other ways that you can be creative with these techniques. What I want you to do is play around with them and see what you can come up with!