Just Got your First Flash? Here’s What you Need to Know

So, the holiday season brought you your first flash. Whether that was by some self-gifting or the kindness of family and friends (lucky you!) doesn’t matter—your next step is figuring out what all those buttons do and how to use that speedlight.

Shutter Speed (Almost) Doesn’t Matter

One thing that will trip many flash beginners up is that shutter speed gets weird. If the flash is too strong, no amount of shutter speed adjustment is going to change how it appears in your final image. A flash will provide a burst of light that only lasts for a fraction of a second, somewhere in the realm of 1/1000 second or faster for most flashes. If your shutter speed is at 1/250 second or 1/50 second, both exposures will receive the full power of that flash. The speed with which flashes operate also explains how they can be used to freeze motion as the flash duration can be faster than the shutter speed.
Aperture is where you will need to go if you want the exposure to change without adjusting the power settings on the flash itself. This is because aperture actually limits how much light can enter the camera, so even though you are getting the full flash blast you can control how much of the blast is captured. This will impact all aspects of your exposure, not just the flash, so set up your aperture as you need it for a scene as a whole. Another option is to adjust the ISO.
Now, you can’t ignore shutter speed. Due to how focal-plane shutters work, you will generally only be able to use shutter speeds up to 1/250 second or slower, unless of course you have high-speed sync capabilities, but more on that later. Shutter speed will affect the amount of ambient light captured. Imagine you are shooting at night without a flash and the image comes out dark. Add a flash and your subject and foreground are perfectly exposed, but the background is still very dark. If you choose a slower shutter speed you may be able to brighten the background while keeping the exposure on your subject the same. This can be used for unique effects, such as light painting or combining long exposures with a sharp foreground subject.