Exposure

In Three Parts

Objective

» Know˃ What exposure is˃ What affects exposure

» Show˃ Define Exposure˃ Identify an over, under, and perfectly exposed photo˃ Use exposure compensation to purposely over and under expose an

image

» Level of Thinking˃ Understand/Apply

But first…

A Quick Review

What does this stand for?

What does this stand for?

What does this stand for?

What does this stand for?

Question 1

» Which of the PSAM modes would you use if motion was most important in your picture?

Question 2

» Name the six examples of “Scene” modes.

Question 3

» What are the two exposure modes used for simple, point and shoot photography?

Question 4

» Which of the P, S, A, M modes would you use if Depth of Field (DoF) in your photograph is most important?

Question 5

» Which of the P, S, A, M modes would you use if you want full control over all the settings?

Exposure

»Box (light-tight)

The important components of any camera are:

»Box (light-tight)

»Hole or Lens (to let the light in)

The important components of any camera are:

»Box (light-tight)

»Hole or Lens (to let light in)

»Shutter (to open and close to let light in at the right time)

The important components of any camera are:

»Box (light-tight)

»Hole or Lens (to let light in)

»Shutter (to open and close to let light in at the right time)

»Film / Sensor (records the light)

The important components of any camera are:

Measuring Light

» Three things affect how much light comes into the camera:˃ Aperture (opening that lets the light in)˃ Shutter (how long the light comes in for)˃ ISO (how much light is needed to make the picture)

» Your camera uses a light meter to measure the light coming in, and sets the aperture, shutter, and ISO so the image will be properly exposed.

Get just the right amount of light, and the image is “properly exposed.”

Too much light, and the image will be OVEREXPOSED

Not enough light and the image will be UNDEREXPOSED

Exposure= Total amount of light which hits the film

Film and sensors require the right amount of light to produce a ‘correct’ exposure.

The settings will be different depending on what you are taking a picture of.

Controlling Exposure

Try it Out

Try it Out

» You can purposely under or over expose a picture on your camera using Exposure Compensation.

» Use the exposure compensation controls on the compact cameras to take the same picture five times:˃ -2 stops˃ -1 stop˃ “properly exposed” (according to camera)˃ +1 stop (over exposed)˃ +2 stops

» Repeat this for FIVE different setups

The Three Parts of Exposure

Three Parts

» Three settings need to be considered when taking a photo:˃ ISO˃ Aperture˃ Shutter Speed

» All three affect the amount of light that reaches the sensor, and how much is needed to get a proper exposure

ISO

» “International Standards Organization”» Controls how sensitive the sensor is to light» The more sensitive it is, the less light it needs to

take the picture» CATCH: A high ISO causes grain in film

photography, now it causes NOISE in digital photography

Aperture

» Size of the opening in the lens» How MUCH light comes in at once

Aperture

Do big holes (apertures) let in more or less light ?

Aperture

F22 f16 f11 f8 f5.6 f4 f2.8What do you notice about the f number as the aperture gets bigger?

Each aperture is twice as big (or half the size) as the aperture next to it.

QUESTION: an f8 aperture lets in twice as much light as f___ and half as much light as f ___

Depth of Field (DoF)

» Aperture affects the DoF in an image» The bigger the aperture, the shorter the depth

of field» Think about the aperture setting as being how

much of the image is in focus» For instance: f/4, 4 feet in focus versus f/32, 32

feet in focus. Bigger number, more in focus.

Shutter Speed

» How long (or short) the shutter is open

» How LONG the light comes in for

Shutter Speed

Changes how long the camera lets light hit the sensor

A whole number of seconds …1 second … 2 seconds … 3seconds

Or a fraction of a second½ second … ¼ second …. 1/8 …. 1/15 etc

Shutter speeds are usually given as a fraction of a second and each shutter speed on a camera is normally about twice as long, or half as long as the next shutter speed.

Work out the missing shutter speeds in this list:

½ ¼ ___ 1/15 1/30 ___ 1/125 ___ ___ ___

SS & Motion

» The shutter speed controls how motion looks in a picture.

» The longer the shutter speed, the more blurred the motion will be.

Altogether

» The ISO, Aperture, and Shutter Speed work together to create a properly exposed image that looks the way you want it to.

How do you know?

Light Meter

Light Meter

» Indicates how much light you need to add or subtract for a “good” exposure

Too Much Light

» If your light meter says you have too much light, you will need to take some away by either making the aperture smaller or shortening your shutter speed.

Not Enough Light

» If your light meter says that you don’t have enough light, you will need to add some by opening up your aperture or lengthening your shutter speed.

Make it a little easier

A Metaphor

A Bucket

The Faucet

Turn it On and Off

Your light meter lets you know when your settings are going to work out,

and whether your bucket will be half full, overflowing, or filled to the brim.

Exposure

Try It Out

Try It Out

» Find a partner.» Study each situation and determine possible

solutions.» Record your solution on notebook paper.» Move on to next station when you are ready.» Return to seat when you are done.