Camera Eyes Human Eye Anatomy Blind Spot Myopia Hyperopia near sightedness farsightedness Animal eyes Compound eyes Ommatididum

1. Section 4
Pages 230-238
Science InAction8
Lesson 7
Image Formation in Humans, Animals and
Cameras

2. I can explain how objects are seen by the eye,

and compare eyes with cameras.
I can investigate and describe the development

of new technologies to enhance human vision.
I can compare the function and design of the

mammalian eye with that of other vertebrates
and invertebrates.

3. IRIS
 colored part of
the eye
controls the

amount of light
entering, which
changes the
size of the pupil
Known as the

diaphragm in a
camera

4. The natural adjustment in

the size of the pupils is
called the iris reflex, which is
extremely rapid.
This iris reflex action the

pupil when you
automatically adjusts go
from a darkened area to a
well-lit area, or, from a well-
lit area to a darkened one.

5. Pupil
 Hole that
light enters
In a camera,

the hole is
known as the
aperture

6. Retina
 Photoreceptor
cells in the retina
detect light (rods
are highly
sensitive to light
and cones detect
color)
They produce

small electrical
impulses from the
retina to the
brain, by way of
the optic nerve.

7. The film at the back of The parts of a camera
 
the camera contains are housed in a rigid
light sensitive lightproof box,
chemicals, which whereas layers of
change when light hits tissue hold the
it. Like the retina. different parts of the
eye together.
These chemicals form

the image on the film.

9. Ciliary Muscles
Contract to

lengthen the
lens and relax
to shorten
the lens

10. In a camera, if an object
 As people become

moves closer to the film,
older, the lens stiffens
the lens must move away
and loses its' ability to
to keep the image in
focus. change shape (doesn't
bulge)
In the human eye, the

lens cannot move, so the
ciliary muscles change the Many people need to

shape of the lens.
wear (convex lens)
The process of changing reading glasses, so that

the shape of the lens is the images can be
called accommodation.
focused.

11. Vitreous Humour
The eyeball

contains fluids,
called humours,
which prevent
the eyeball
from collapsing
and refract the
light that enters
the eye.

12. The lens in the human

eye is a convex lens,
which focuses the light
rays entering your eye
to a point on your
retina .
Some people however

have eyes that are too
long or too short.

13. If the eye is too

long, the image
forms in front of
the retina
trouble seeing

distant objects

14. If the eye is too

short, the
image forms
behind the
retina
Objects that are

close to them
are difficult to
see

15. The shortest distance On average, an adult
 
at which an object is has a near point of
in focus is called the about 25 cm, whereas
near point of the eye. babies have a near
point of only 7 cm.
The longest distance

is called the far point The far point is

of the eye. infinite.

17. In 1966, Theodore H.

Maiman, a physicist at
Hughes Aircraft
Company in California
became the first person
to use the L.A.S.E.R.
Light Amplification by

the Stimulated
Emission of Radiation

18. Laser light is quite Lasers have many useful

different. applications:
 Scanners (bar codes in
It gives off a single retail shops are scanned

wavelength (frequency) to give the price)
of coherent light.  Digitized data are read
by a laser on a compact
disk (CD)
 Lasers are use by law
enforcement officers to
detect the speed of
vehicles.

19. Laser light can be In either form, it is so
 
released in pulses or in powerful, that it can
a continuous beam. make precise cuts
through metal
 Can also be used in
surgery, as a scalpel -
or, to instantly seal
broken blood vessels,
because it produces
such intense heat.

20. The surgeon cuts a thin flap of tissue covering the eye,

fold it over, then the cornea is reshaped with a laser.
The reshaped cornea acts like a corrective lens,

allowing the light to be bent so it will properly focus on
the retina.

21. Light is focused onto an

image intensifier.
Inside the intensifier, the

light energy releases a
stream of particles,
which hit a phosphor-
coated screen.
These glow green and

the person looking in the
goggles can view a green
image.

22. The point where the View this image at arm's
 
retina is attached to the length.
optic nerve does not Cover your right eye with

have any light sensitive your hand.
cells. This point is known Stare at x, slowly leaning

as the blind spot. closer to the image, until
the dot disappears (when
Page 233 for the activity you reach your blind

spot) and then reappears
when you have passed
your blind spot.

23. ... explain how objects are seen by the eye,
and compare eyes with cameras?
... investigate and describe the
development of new technologies to
enhance human vision?

24.  Page 235, 1-5
#1. Make a chart that lists the parts of the eye and the parts
of the camera, and their function. What do the camera
and the eye have in common? How are they different?

25. Page 235, 1, 3-5

#3. What does the laser surgery method of
vision correction have in common with
wearing glasses to correct vision?
______________________________________
______________________________________
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26. Page 235, 1, 3-5

#4. If you wish to take a picture of faint stars in
the night sky, how should you adjust your
camera?
______________________________________
______________________________________
______________________________________
______________________________________
______________________________________

27. Page 235, 1, 3-5

#5. Describe how night vision goggles enhance
human vision.
______________________________________
______________________________________
______________________________________
______________________________________
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29. Eyes that have a

cornea, a lens and a
retina are called
camera eyes.
Vertebrates (animals

with backbones) for
the most part have
camera eyes.

30. Fish have camera

eyes with a perfectly
round lens.
It bulges out from the

pupil, allowing it to
see in practically
every direction.

31. Birds have sharper

vision than humans
because they have five
types of cones (humans
have only 3).
All are sensitive to

different wavelengths
of light.

32. Nocturnal animals They also have many
 
have eyes that collect more rods than cones
as much light as in their retina making
possible because of their eyes more
their very large pupils. sensitive to low levels
of light.
They also have a layer,

called tapetum
lucidum, inside their
eye, which acts as a
mirror.

33. Insects and An ommatidium looks
 
crustaceans have like a long tube with a
compound eyes. lens on the outer surface,
a focusing cone below it,
Each eye is made up of and then a light sensitive

many smaller units cell below that.
called ommatidium.

36. The compound eye is

great for spotting
movement, but with
so many lenses it is
difficult to form a
single coherent image.
Instead it forms a

mosaic image (much
like a tv screen).

37. ... compare the function and
design of the mammalian
eye with that of other
vertebrates and
invertebrates?

38. Page 238, #1-3

#1. How is a human eye similar to and different
from a bird’s eye?
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______________________________________

39. Page 238, #1-3

#2. How is a compound eye different from a
human eye?
______________________________________
______________________________________
______________________________________
______________________________________
______________________________________
______________________________________

40. Page 238, #1-3

#3. How does an ommatidium help an insect
survive and thrive in its environment?
______________________________________
______________________________________
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