Exposure VariablesISO and Shutter Speed

IntroExposure and composition are dependent on three variables:

ISO settingshutter speedaperture setting

ISO setting The ISO “speed” determines how

sensitive the camera’s image sensor is to light.

A high ISO speed requires less light, but produces a grainier image.

A low ISO speed produces a clearer image, but requires more light.

Source: http://camerasim.com/slr-camera-explained/

Common ISO Settings100 – bright, sunny day outside200 – cloudy day outside400 – well-lit indoor800 – darker indoor situation1600 – night/low light

Shutter speed setting Shutter speed is how long the shutter

“curtain” stays open to allow light into the camera.

A fast shutter speed allows you to “freeze” action in a photo, but reduces the incoming light.

A slow shutter speed lets in more light, but can cause motion blur in the photo

Source: http://camerasim.com/slr-camera-explained/

Shutter Speed settingSetting number represents a FRACTION (250 = 1/250 of second)

Big number = less lightSmall number = more light

Common Shutter Speed Settings

Common settings: B, 1 (1 sec.), 2 (1/2 sec.), 4, 8, 15, 30, 60, 125, 250, 500, 1000, 2000, 4000

Any number with “ behind it indicates seconds

Exposure VariablesAperture

Intro The aperture is the size of the hole light

passes through at the moment a photo is taken.

Source: http://camerasim.com/slr-camera-explained/

Aperture The aperture setting is also referred to

as f/number or f/stop. A high f/number makes more things in

focus, but reduces the amount of light entering the camera.

A low f/number makes backgrounds blurry and allows more light into the camera.

Source: http://camerasim.com/slr-camera-explained/

Common Settings 2, 2.8, 4, 5.6, 8, 11, 16, 22 (every other

setting is twice as much or half as much light as last setting)

Depth of Field Depth of field is the range of focus. A long depth of field means more will

be in focus – the foreground, middle ground and background.

A short depth of field means less will be in focus – the foreground only, for example.

In a nutshell… The larger the f-stop (bigger number),

the longer the depth of field. The shorter the f-stop (smaller number),

the shorter the depth of field.

Discussion Time Get into groups of three. Everyone in a group will receive a sheet of

paper. Everyone will get 30 seconds to write down

important phrases about their word. Each person will share what they know about

the subject using only the words written on their sheet to help them.

Mrs. Bass will call on someone from each group to summarize what each group knows about the topics.

Equivalent Exposure

IntroFor each photo, there are multiple

settings that will give proper exposure. This concept is equivalent exposure. A photographer chooses the settings based on the desired look of the photo.

Motion/Blur If motion or blur is the biggest concern,

the photographer sets the shutter speed first, and then sets the aperture setting.

Explanation For each shutter speed increase, the

aperture setting must decrease to give same amount of light. Less time open, so opening needs to be larger.

For each shutter speed decrease, the aperture setting must increase to give the same amount of light. More time open, so opening needs to be smaller.

Depth of Field (DOF) If depth of field is the biggest concern,

the photographer sets the aperture first and then sets the shutter speed setting.

Explanation For each aperture setting decrease, the

shutter speed setting must increase to give same amount of light. Larger opening, so less time is needed open.

For each aperture setting increase, the shutter speed setting must decrease to give the same amount of light. Smaller opening, so more time is needed open.

In a nutshellWhen one goes up, the other goes

downWhen one goes down, the other

goes up

Exposure VariablesReading the Light Meter

Intro The lens light meter is built into the

camera and reads the light that passes through the lens.

The meter displays the amount of light reaching the film based on the ISO, shutter speed and aperture settings.

Goal The goal is to have the arrow in the

center value, which is zero on our light meters, because this indicates proper exposure.

To reach this goal, the photographer will have to change the exposure settings until the indicator reaches zero.

Remember: Because of equivalent exposure and that there will be multiple settings to achieve proper exposure.

Explanation The numbers below zero indicate that

there is not enough light and that the image will be underexposed.

The numbers above zero indicate there is too much light and the image will be overexposed.

Underexposure If the light meter shows underexposure

no matter how much you change your aperture or shutter speed, both settings need to go down and the ISO needs to increase.

Overexposure If the light meter shows overexposure

no matter how much you change your aperture or shutter speed, both settings need to go up and your ISO needs to decrease.

Discussion Time Get into groups of three. Everyone in a group will receive a sheet of

paper. Everyone will get 30 seconds to write down

important phrases about their word. Each person will share what they know about

the subject using only the words written on their sheet to help them.

Mrs. Bass will call on someone from each group to summarize what each group knows about the topics.