The biggest reason photographers want to use the flash on camera is to get better photos in low light situations. What most people think, is this:
“If I get a flash and I put it on my camera, then I won’t get the slow shutter speeds and all these motion blurry photos when I shoot in low light!”
But then when you put your flash on the camera, and you start taking pictures in low light, the flash fires, but you still end up with blurry photos with long slow shutter speeds.
The reason this happens is because of how you’re shooting and how you have to think about flash photography. See when you’re shooting with the flash, you’re always shooting with two different light sources.
The first is the ambient light, which could be the sun or the lights in the room that you’re shooting in, like my studio lights.
The second light source is the flash, and these two light sources are different kinds of light.
The ambient light is a continuous light source, meaning that the light is always on and always being recorded the entire time you take a photo, while the flash is an instantaneous light source, meaning that the light flashes very brightly for a very brief moment.
How long the flash bursts varies, but it’s usually something like 1/8000th of a second.
What that means is that if the shutter speed is set to something like 1/10th of a second, the flash fires on and off long before the camera finishes capturing all of the ambient light.
So when you mix these two different kinds of lights together, you have to set your settings on your camera differently.
If you want the flash to do what most people think it should do, to allow you to shoot in low light, but use fast enough shutter speeds to get a sharp photo, if you just throw your flash on the camera and then do everything like you normally do, you’ll still get those long slow shutter speeds and all the blurry photos that comes with them.
This is because the camera treats the flash as what’s called a fill light, when you want the flash to be the main light.
In any lighting situation the main light is the dominant light source in the scene, and the main light is always given priority in the exposure settings.
The fill light is treated as a secondary light that is meant to add a little bit of light in the scene to fill in the shadows.
So if the ambient light is being treated as the main light, then the camera’s going to use that long slow shutter speed to expose the ambient light correctly. If you want to use the flash as the main light and use your ambient light as fill, then you have to set the settings on the camera to do that.
Fortunately, doing this is actually very simple. If you’re shooting in manual mode, all you do is set your exposure settings so that your exposure indicator reads in the negative, under exposing the ambient light.
How underexposed the ambient light is will depend on the shot you’re taking, but regardless of the exposure reading, you want to make sure that your shutter speed is fast enough to give you a sharp photo.
Now if you’re shooting in a priority mode, you would use your exposure compensation to underexpose the ambient light and set it as fill, and if you’re shooting in a priority mode, you’ll still need to check your shutter speed to make sure it’s fast enough to give you a sharp photo.
Once you’ve set your settings for the main light, you can now set your flash. If you’re using a manual flash you will need to set the flash power.
This will likely require a few test shots at different power levels until you find the power setting that works best for the photo you’re trying to take.
If you have a TTL flash, you can use the TTL function to let the camera and the flash work together to set the power level for you.
I used to be scared of my flash, and I understand how intimidating flash photography can be, but a flash is just a tool. Once you understand how that tool works you’ll be using your flash to create photos that used to seem impossible.
If you want to master your flash and take those amazing photos, check out my Understanding Flash Photography Video Course.