This is Lesson 10 of 10 in “The Ultimate Guide to Shutter Speed” Series. If you missed any of the prior lessons, go to davidmolnar.com/shutter-speed for a comprehensive look at how shutter speed affects your photos - and how you can use it creatively for stunning images. There are tutorials, infographics, cheat sheets at more, so go check it out now.
When using a flash, there are some things you need to think about, including the ambient light in the situation.
Ambient light is any available light, and flash is supplemental light.
Shutter speed does not affect how much light hits your subject (will not change the exposure.) The amount of light that hits your subject in flash photography is due to the power of the flash, the aperture of your lens and the ISO setting of your camera.
Your camera and flash communicate with each other. The maximum shutter speed they can communicate with each other is 1/200 of a second for most cameras. This shutter speed (1/200) is known as maximum sync speed.
What happens when you shoot at shutter speeds about 1/200 with a flash is that you’ll see a black line in your photo. This is actually part of the shutter that gets caught in the frame.
You can combine flash and shutter speed creatively at slow shutter speeds in a technique called light painting. The flash will freeze the subject, but leaving the shutter open after the flash fires allow you to introduce secondary light sources in the background. This is a great way to convey motion and energy in a room.
Using a flash in bright sunlight will light the subject’s face but will also seem to darken the sky because of the short time the shutter is open.