1. PINHOLE CAMERA What do we need to know?
Light travels in straight lines
A pinhole is a tiny hole

2. Camera Obscura Camera Obscura (latin) > Dark Room
Projects a view of the outside onto the inside walls
The image is upside down

3. Collecting Place / Locked Treasure Room
The history…
5th Century BC:
Mo-Ti
322 BC:
Aristotle
965 AC:
Alhazen
1500s:
Leonardo Da Vinci
Collecting Place / Locked Treasure Room

4. Pinhole: Bright Object Light reflects off bright surface
Small Hole >> Sharper Image
Bigger Hole >>Brighter Image
Bright Object
Light reflects off bright surface
Pass through small holes
Light rays cross
Upside down image on wall
Small Hole

5. The history… Used for observing eclipses 1558 > Lenses and mirrors
Leonardo Da Vinci:
"When images of illuminated objects ... penetrate through a small hole into a very dark room ... you will see [on the opposite wall] these objects in their proper form and color, reduced in size ... in a reversed position, owing to the intersection of the rays". Leonardo da Vinci
Used for observing eclipses
1558 > Lenses and mirrors

6. 1558 1568 1700 1728 1558: Lens Based Camera Obscura, 1568
Correct for reversed image
1568
1700: Hooke described ‘picture box’ in a paper to the Royal Society
1700
1728: Reversed the specimen to overcome upside down image
1728

7. The history… 1700 – 1900 1898 1970 Silicon Image Detector, 1970
Translucent screen + 45° mirror: Override two inversions of image
But here’s the puzzle. How could the images projected by the camera obscura stir up the emotions
and widen the horizon of visual experiences of the likes of Huygens and, later on, Vermeer? After
all, versions of this instrument had been around long before this period. The pinhole camera, for
example, was known and used in classical antiquity in an astronomical setting, particularly for
observing solar eclipses. From antiquity up to the Renaissance, the camera obscura never fell into
total oblivion. Now and then, it was mentioned and occasionally used, mostly for astronomy. But
it did not attract very much attention. At the end of the 16th century, however, its fortunes
changed dramatically. The pinhole camera obscura was equipped with lenses and mirrors and
transformed into the optical camera obscura of the early modern period. 4
Although no single optical camera obscura has survived from the 17th century, we know from
written sources and a few book illustrations that at least four principal types of this camera were
developed and in use. The simplest arrangement, with a lens fastened in the pinhole, projected an
inversed and reversed image on a vertical screen opposite the aperture. A variation on this
employed a translucent screen, allowing the viewer to see the image from the other side, thereby
correcting the left-to-right reversal. These two types of camera projected the image directly and
could be combined in one device. There were at least two additional incarnations of the camera
obscura, which used a mirror oriented at 45 degrees to the path of light to achieve vertical
reversion. Without a translucent screen the projected image remained horizontally reversed, but
with a translucent screen this too could be overcome (Figure 2). Judging from contemporary
illustrations, standardized forms of these four types were slow to replace makeshift, ad hoc
constructions put together on site to meet a specific need. If the earliest optical camera obscuras
were indeed temporary devices, this could explain why none appears to have survived.
1898
Silicon Image Detector, 1970
1970

8. Digital Cameras/ SLR The history… 1888 Kodak handheld camera 1959
Camera sent back to Kodak for processing
Digital Cameras/ SLR
Reflect IR beam off subject + focus lens
But here’s the puzzle. How could the images projected by the camera obscura stir up the emotions
and widen the horizon of visual experiences of the likes of Huygens and, later on, Vermeer? After
all, versions of this instrument had been around long before this period. The pinhole camera, for
example, was known and used in classical antiquity in an astronomical setting, particularly for
observing solar eclipses. From antiquity up to the Renaissance, the camera obscura never fell into
total oblivion. Now and then, it was mentioned and occasionally used, mostly for astronomy. But
it did not attract very much attention. At the end of the 16th century, however, its fortunes
changed dramatically. The pinhole camera obscura was equipped with lenses and mirrors and
transformed into the optical camera obscura of the early modern period. 4
Although no single optical camera obscura has survived from the 17th century, we know from
written sources and a few book illustrations that at least four principal types of this camera were
developed and in use. The simplest arrangement, with a lens fastened in the pinhole, projected an
inversed and reversed image on a vertical screen opposite the aperture. A variation on this
employed a translucent screen, allowing the viewer to see the image from the other side, thereby
correcting the left-to-right reversal. These two types of camera projected the image directly and
could be combined in one device. There were at least two additional incarnations of the camera
obscura, which used a mirror oriented at 45 degrees to the path of light to achieve vertical
reversion. Without a translucent screen the projected image remained horizontally reversed, but
with a translucent screen this too could be overcome (Figure 2). Judging from contemporary
illustrations, standardized forms of these four types were slow to replace makeshift, ad hoc
constructions put together on site to meet a specific need. If the earliest optical camera obscuras
were indeed temporary devices, this could explain why none appears to have survived.
1959
J-Phone:
Cost: $ 500
110,000 pixels (0.1 MP)
2000

9. Ray diagrams:

10. Making a pinhole camera …
It can be very simple!
Dark box or tube + a tiny hole in the front
We’ll use a screen for viewing on the back instead of film

11. STEp 1
Roll a tube of black card OR
make a box with two open ends

12. STEp 2
Use the tinfoil to cover one end
(Blocks light from entering)

13. STEp 3
Make a tiny pinhole in the front

14. STEp 4 4
Add a screen to the back
The image will appear here

15. STEp 5 The image will be dark so you’ll need to cover the screen
Make a cover that wraps around the screen.

16. TEST IT!

17. STAR

18. SUN

20. Problems with pinholes
image plane
effective focal length, f’
optical
axis y x z
pinhole

21. Problems with pinholes
Pinhole size (aperture) must be “very small” to obtain a clear image.
However, as pinhole size is made smaller, less light is received by image plane.
If pinhole is comparable to wavelength of incoming light, DIFFRACTION
effects blur the image!
Sharpest image is obtained when:
pinhole diameter
Example: If f’ = 50mm,
λ = 600nm (red),
d = 0.36mm

22. Image Formation using (Thin) Lenses
Lenses are used to avoid problems with pinholes.
Ideal Lens: Same projection as pinhole but gathers more light! i o
Gaussian Lens Formula:
f is the focal length of the lens – determines the lens’s ability to bend (refract) light
f different from the effective focal length f’ discussed before! P P’ f

23. Two Lens System
Rule : Image formed by first lens is the object for the second lens.
Ray passing through focus emerges parallel to optical axis.
Ray through optical center passes un-deviated.
image
plane
lens 2
lens 1
object
intermediate
virtual image
final
Magnification:

24. The Eye The human eye is a camera!
Iris - colored annulus with radial muscles
Pupil - the hole (aperture) whose size is controlled by the iris
Photoreceptor cells (rods and cones) in the retina

25. PINHOLE CAMERA
How to Build It