1. Unit 3 – Topic 4
Eyes & Cameras

2. Eyes vs. Camera
You can think of the eye & camera as an “image producing” technologies
1 is natural
1 is artificial
Cameras are built on the principles of human sight
Their components are very comparable!

3. Light Entering
Aperture

4. Light Entering
Eye Camera
Pupil Aperture
Allows light in

5. Light Entering Pupil Aperture Eye Camera Little = small
How much light depends on how much light is needed
Eye Camera
Pupil Aperture
Little = small
Allows light in
Lots = big

6. Light Entering Lots = big Little = small
How much light depends on how much light is needed
Lots = big
Little = small

7. Light Entering How is this all controlled?
Eye = tiny muscles around the eye called the iris
Colour of iris is your eye colour

8. Light Entering How is this all controlled?
Camera = cylinder or dial around the aperture that when turned increases or decreases the size of the aperture

9. Inside The Eye Light enters eye through pupil
Light goes into the retina
Retina is covered with photoreceptors

10. Inside The Eye Photoreceptors Rods Cones Two Types 3 Types Green Red
Blue
Two Types
Rods
Cones
Sensitive to Light
In low light only detect shades
Operate in Low light
Detect Colour

11. Inside The Eye

12. Inside The Eye Photoreceptors send messages to optic nerve
Optic nerve sends messages to the brain
Brain creates an image  film on camera

13. Light Entering

14. Focusing Light Eyes & Cameras have transparent lenses
Lens must be in right position to sharpen image (double convex)
Muscles attached to lens (ciliary muscles) contract to lengthen & relax to shorten

15. Focusing Light

16. Focusing Light

17. Focusing Light
Changing the shape of lens focuses the image on the retina
Cameras do this automatically when they have the auto-focus feature & can be done manually

18. Correcting Vision Issues
Most eye problems fall into two categories
Nearsightedness
Farsightedness
Cannot see objects far away
Cannot see objects close up

19. Correcting Vision Issues
Lens not fat enough
Lens not thin enough

20. Inside The Eye
Why is the image upside down when it reaches the brain?

21. Laser Eye Surgery Used to replace the need for glasses/contacts
Cuts flap in tissue
Covering the eye
Reshapes cornea
Which acts as the
new corrective
lens
Folded back so cornea
is exposed
Reshaped with UV light pulses

22. Laser Eye Surgery

23. Laser Eye Surgery

24. Laser Eye Surgery

25. Night Vision Goggles 2 Lenses and 1 Viewing Screen
In general they intensify
an image and project it
on to a screen
Which is why the
image is green
Screen is covered in phosphor
Phosphor glows green when hit with light (particles)

26. Night Vision Goggles

27. Camera Eyes We like to compare eyes vs. cameras If they have …
Roughly round in shape
Cornea
Lens
Retina
We call them camera eyes

28. Camera Eyes They can vary Bees see UV light
Can see different wavelengths
Fish
Birds
Large lens (goes through pupil)
Ultra sharp vision
Allows them to see all directions
More cones than humans

29. Camera Eyes Nocturnal Have more rods
Acts like a mirror which reflects light
Awake at night
Large pupils (Capture more light)
Tapetum Lucidum
Extra layer in eye

30. Camera Eyes

31. Camera Eyes

32. Made up of many individual “eyes”
Compound Eyes
Made up of many individual “eyes”
Each unit ommatidium
Focusing cone
Long Tube
Lens on
outer surface
Light sensitive cell

33. Compound Eyes These eyes tend to be convex
Makes them excellent at detecting motion

34. Compound Eyes There are some drawbacks Works like a TV / Pixels
Difficult to form a single image
Works like a TV / Pixels
More ommatidium better image

35. Digital/Stadium Images
Each card contains a coordinate
When pieced together they form an image

36. The image is made up of pixels
Digital Images
Digital Images
The process of creating an image using a computer
The image is made up of pixels
From the term
Picture Elements
Pic Ele

37. Colouring Digital Images
Each pixel is given
a value
Each value corresponds to a colour
That pixel then displays that colour

38. Many more small squares
Image Quality
Size of Pixel
Large
Small
Many small
squares
Many more small squares
Low resolution
High resolution

39. Capturing A Digital Image
Light Enters through aperture
This can be stored and transmitted
Converted to digital information
Reaches a CCD
(Charged-Couple Display)
Small electrical
current charges
squares
Like grid-paper

40. Transmitting Digital Transmission
Can also see different light spectrums
Information can be coded, transmitted coded, reassemble by a computer
Without this we would not be able to transmit information anywhere