The Balancing Act
You’d slow down the shutter speed if you want motion blur, right? But that also means your image will get brighter...
ISO Side Effect
The image gets brighter when you raise the ISO, but the side effect is a more "noisy" or grainy image.
Aperture Side Effect
While slow shutter speeds create motion blur, the side effect of changing the aperture is the level of background blur.
Shutter Side Effect
The side effect of changing the shutter speed is the amount of motion blur. To convey motion, use a slow shutter speed (shutter open for a longer time).
When you hit the shutter button, the camera captures the scene for the duration the shutter is open (shutter speed).
A Bucket Full of Light
The camera needs a certain amount of light to create a perfectly exposed image--not too bright, not too dark. Your job is to ensure the camera gets the light it needs.
What is ISO
The aperture and shutter let light in (and you can change the aperture size or the shutter duration to control how much light you want in), but when the light ultimately reaches the sensor, the sensor decides how much of this light it wants to soak in.
How we Measure the Shutter
The shutter is a curtain that opens and then closes after a bit. The longer it's open, the more light that goes through, but we need to know precisely how long it's open, so we have a unit for it: shutter speed.
How the Shutter Works
The shutter is a curtain that's always closed. When you click the shutter button, the curtain opens for a bit to let the light in, and then closes again. You can control how long it stays open.
How we Measure the Aperture
Just as we measure weight in lbs or kgs, we also need a unit for the aperture--so, whatever camera you use, you'll know exactly how bright or dark the image will be when you change the aperture size.
How the Aperture Works
Aperture is just a fancy way of saying "hole." The lens has a hole in it so light can pass through. You can make the hole larger or smaller depending on your needs.
How the Camera Works
Light goes into your camera, through the aperture and shutter, and ultimately hits the sensor.