Office hours are posted on the website.

1

• Office hours are posted on the website.
• Molly Tuesdays 2-4pm
• Dr. Keister Wednesdays 10am-12
• Prof. Goldman Wednesdays 2-330pm
• All office hours are in the help room downstairs.
• I have unclaimed homework at the front.

2
Homework Policies

• Homework is due at the beginning of class. It
  will be collected 15-20 minutes after the start
  of class.
• Homework will be accepted until the end of class,
  with points deducted for lateness.
• No homework is accepted after class is over,
  because the solutions are posted on the website.

3
Exam 1!

• First exam is next Thursday, October 4th.
• It will be in class.
• It will cover chapters 1-3.
• There is no homework due next week.
• We will try to post a practice exam this week.
  Check the website.

4
Chapter 4 Cameras and Photography

• Pinhole Camera
• Review image formation
• Focusing
• Lens-based Cameras
• Essential parts
• Focusing the image
• Depth of focus
• Depth of field

• Types of cameras
• View camera
• Single lens reflex
• Rangefinder

5
Pinhole Cameras
Pinhole camera
Object
Image

• Light rays from each point on the object reach
  one point on the screen, and no rays from other
  points on the object reach that same point on the
  screen.
• This produces a focused image.

6
Clicker Question

• Which camera will produce the smallest image of
  the light bulb?
• A
• B
• C
• D, they are the same size

A
B
C
7
Clicker Question

• Which camera will produce the smallest image of
  the light bulb?
• A
• B
• C
• D, they are the same size

A
B
C
8
Pinhole Cameras
Pinhole camera
Object
Image

• Remember that the object does not have to be
  self-luminous. The rays reflected from a light
  source will also enter the pinhole and can image
  the object.

9
Pinhole Camera
Object
blurry image
If we increase the size of the hole in a pinhole
camera, we get more light, but the image gets
blurry, because rays from each point on the
object hit more than one spot on the screen, and
rays from more than one point on the object reach
the same spot on the screen
10
Camera with Lens
Object
Image

• Adding a lens bends the rays so that rays from
  each point on the object reach only one point on
  the screen, and no rays from other points on the
  object reach that point. This produces a focused
  image on the screen.

11
Image Size and Zoom

• To produce a larger image with a pinhole camera,
  you can either decrease the distance from the
  object to the camera, or increase the distance
  from the pinhole to the back screen of the
  camera.
• The image stays in focus because only one ray
  from each point on the object gets through the
  pinhole and reaches the screen

12
Camera with Lens Zoom

• Just increasing the distance between the lens and
  the back of the camera does not increase the size
  of the image. The image no longer focuses on the
  back of the camera.

13
Camera with Lens Zoom

• To produce a larger image, in focus, with a
  camera that has a lens, you have to both move the
  position of the screen and change the focal
  length of the lens.

14
Focusing

• As weve seen, objects at different distances
  from a lens will result in focused images at
  different distances behind the lens.
• This means that a camera has to allow the lens to
  move so that the image will be focused to the
  plane of the film for different object distances.

15
Essential Parts of a Camera
diaphragm
film or screen
shutter
lens

• The components are all mounted in a light-tight
  box. The bellows allow the photographer to change
  the distance between the film and the lens.

16
Focusing

• We have thus far been drawing lens diagrams as if
  the lens focuses to exactly one spot.
• In reality, film and digital sensors have
  limitations that prevent them from recording a
  perfectly focused image.
• In addition, there is some amount of blurring
  that is not detectable even by your eyes.
• Thus there will be a range of image locations
  that will be acceptably focused.

17
Depth of Focus

• In a pinhole camera, the object is in focus at
  any plane behind the pinhole. This is an infinite
  depth of focus

size of acceptable blur
depth of focus
18
Depth of Focus
depth of focus

• If we reduce the size of the lens, but do not
  change the focal length, the depth of focus that
  generates the same size blur becomes larger.

depth of focus
19
Depth of Field
size of acceptable blur
depth of field

• Depth of field refers to the range of object
  distances that will produce an acceptably focused
  image at a given film position
• It is a measure of how far apart two objects can
  be and still both be in reasonable focus on the
  film

20
Depth of Field Object Distance

• As the distance to the objects increases, the
  depth of field increases.
• Here the two objects are farther apart than
  before, but they focus to almost the same film
  position.

21
Finding Focusing Distance

• A camera is focused by changing the distance
  between the lens and the film or CCD at the back
  of the camera
• Lets say our camera has a lens with focal length
  1 cm.
• We want to take a picture of a friend 100 cm from
  the camera. Where should we put the film?
• Note that the image distance is very close to the
  focal length. This is because the object distance
  is much larger than the focal length
• What if we are looking at a flower 5 cm from the
  camera?

22
Camera Examples View Camera
23
Camera Examples

• Some old cameras did not have an adjustable
  diaphragm, and could only be used in bright
  outdoor conditions

24
Camera Examples
25
Rangefinder and Viewfinder Cameras
26
Single-lens Reflex (SLR)
27
Point-and-Shoot Digital