Today's digital cameras do a lot for us,

but there's no replacement for the human eye.

It's important to learn

how cameras work with light to create an image,

that way we'll know what's going on

when it's time to capture a moment.

There are three variables

that determine if you're getting the right amount of light

for the correct exposure.

With a manual camera,

we're able to change any of the variable ourselves.

Different settings can result in really different pictures.

Let's look at the process together.

First, see this here?

This is the aperture.

It's the hole that light passes through.

If we make the aperture big,

we'll have more light, true,

but the sharpness of your photo will decrease

very quickly from your focus point,

backward and forward.

This is what we call shallow depth of field.

If we have a very small aperture,

we'll have less light but a deeper depth of field.

For portraits, it can be nice to have a sharp figure

separate from a somewhat blurry background

so I would suggest a large aperture.

Aperture is measured in f-stops.

This can get a little confusing

because lower numbers mean bigger apertures

and higher numbers mean smaller apertures.

Next, there's shutter speed to think about.

The shutter acts like a curtain

that covers the sensor,

and it only opens when you release the shutter button.

If we want less light,

we open the shutter for a shorter time.

If we want more light,

we open it for a longer time,

but we run the risk of getting

a motion-blurred picture.

The speed is measured in seconds

and fractions of seconds.

For shooting sports or anything with a lot of movement,

we'll need faster speeds.

For taking awesome night landscapes,

longer exposures will be better,

but we'll need a tripod to steady the shot

and prevent motion blur.

Another cool thing we can do with light exposures

is light painting,

drawing in the dark with a torch

or the light of a cell phone.

Lastly, ISO sensitivity controls

how sensitive the sensor is to light.

If we use low sensitivity,

we'll need more light to register a photo.

With a higher sensitivity,

we'll be able to get a picture

with less available light.

100 ISO is a low sensitivity,

while 6400 ISO is a high one.

If we increase sensitivity,

we'll be able to use faster speeds

and smaller apertures,

but we'll get noisier images.

Good thing we have something to tell us

if we're getting the correct amount of light

to get a good exposure,

the light meter.

Sound good to you?

Now it's time to get out there

and practice taking pictures

under different conditions,

so you know what to do

any time you want to take the best picture.