I presented Photo Basics to a room full of pizza eating designers, researchers, and engineers as part of a series of lunch time presentations at Insight Product Development. The focus was on covering the basics that would lay the groundwork for a specialized lighting workshop targeted at improved photography for each discipline's needs.

1. Photo Basics

3. FOCUSING RING
ZOOM RING
FOCUS MODE
SHUTTER BUTTON
MAIN DIAL
SETTING CONTROLS
LCD DISPLAY
MODE DIAL
HOT SHOE

5. VIEWFINDER
CONTROL DIAL

7. PC TERMINAL
REMOTE CONTROL
TERMINAL
LENS RELEASE

10. Light through the lens is
redirected by the reflex mirror.
PENTAPRISM
A pentaprism flips the image
and redirects it into the
viewfinder.
VIEWFINDER
FILM / SENSOR
REFLEX MIRROR

11. When the shutter release is
pressed, the reflex mirror flips
up, sealing the chamber (from
light from the viewfinder) and
allowing the light from the lens
to expose the sensor.
PENTAPRISM
VIEWFINDER
FILM / SENSOR
REFLEX MIRROR

12. Understanding exposure

16. OPTIMUM
EXPOSURE

17. Exposure
DEFINED:
Exposure is the total amount of light that film or
an image sensor is allowed to be exposed to.
Depending on the amount of light you’re photographing and
the camera’s dynamic range (useful exposure range) there’s an
optimum or correct exposure.
Anything else, unless intentional, is either
over or under exposed.

18. Exposure
UNDEREXPOSURE
Shadows are “blocked up”,
losing their details and
rendered as all black or at tones
undistinguishable from black.
“CORRECT” EXPOSURE
OVEREXPOSURE
Highlights are “blown out”
or “washed out”, losing their
details and rendered as all
white.

19. Exposure
CONTROLLING EXPOSURE
There’s a number of interdependent variables that can be
manipulated to get to the right amount of light for a correct
exposure.
ISO
SHUTTER SPEED
APERTURE
LIGHTING

20. ISO
Think: size of the bucket.
LOW ISO
NUMBER
HIGH ISO
NUMBER

21. ISO
DEFINED:
ISO is the standard system for measuring film
speed, a film’s sensitivity to light.
Lower ISO numbers represent lower sensitivity (a larger bucket),
thus requiring more light; higher ISO represent higher sensitivity (a
smaller bucket), thus requiring less light.
The ratio of two ISO numbers represent their relative sensitivity
(e.g. ISO 200 will take half as long to achieve the same exposure as
an ISO 100, all else being equal).
Digital cameras have an ISO-equivalent adjustment option, which
determines the sensitivity of the image sensor.

22. ISO
Consequences?
Grain in film, noise in digital.
Film emulsions are made up of silver halide grains.
Faster films have larger grains that are more sensible
to light, but easier to notice in prints.
Faster ISO speeds in digital are instead achieved by
amplifying the image signal, which unfortunately
amplifies noise as well. Ironically, slower ISO
speeds require longer exposures, which are likely to
introduce the noise to begin with.

23. ISO
LOW ISO
HIGH ISO
Noise is less perceptible, but
needs more light exposure.
Noise is amplified, and most
evident in dark areas, but
needs less light exposure.
Use low ISOs (100, 200) for
sunny shots (outdoors or a
well lit room), or when using
lighting equipment.
Use high ISOs (400) for low
light conditions (e.g. cloudy
days) or night-time shots
(800+).

24. Shutter speed
Think: time the valve is left open.
FAST SHUTTER
SPEED
SLOW SHUTTER
SPEED

25. Shutter speed
DEFINED:
Shutter speed is the time the shutter is left open for
light to hit the film or image sensor.
This is often referred to as “exposure time”, where a faster shutter
speed (less time open) creates a shorter exposure time.
Shutter speed is measured in seconds: 30+ seconds to about
1/4000 second, and are directly proportional to light (e.g. 2 seconds
will allow twice the light to hit the sensor as 1 second would, all else
being equal)

26. Shutter speed
Consequences?
Motion blur.
Slow shutter speeds can create motion blur from
moving subjects, while faster shutter speeds can
“freeze” moving subjects.
Also, there’s camera movements (shakiness), making
it hard to hand-hold a long exposure.

27. Shutter speed
FAST SHUTTER SPEED
SLOW SHUTTER SPEED
Movement is “frozen”, but produces less light
for exposure.
Movement is blurred, but produces more light
for exposure.
Use faster shutter speeds (1/250 - 1/1000
second) to freeze slow movement like
walking; faster (1/500 - 1/2000 second) for
fast movement like running.
Use slower shutter speeds (1 - 4+ seconds) to
capture motion, but use a tripod or similar
support.

28. Shutter speed
HOW DO SHUTTERS WORK???
Conventional camera shutters have a slit in them (technically,
the gap between the two “shutter curtains”), which travels from
one side of the sensor to the other, allowing light to hit it. Shutter
speed is determined with the width of this slit and the time it takes
it to travel the length of the film/sensor.
LIGHT
SHUTTER
FILM/SENSOR

29. Aperture
Think: the diameter of the spout.
SMALL
APERTURE
LARGE
APERTURE

30. Aperture
DEFINED:
An aperture is an opening that controls the “area”
over which light can pass through the lens.
Aperture settings are measured in f-numbers or f-stops, which
correspond to the focal length to effective aperture diameter.
An f-number of f/1 would mean the aperture is completely open,
while f/2 would be half that diameter (think 1/2 = 0.5). The larger the
aperture (smaller number, if not thinking in fractions), the more light
allowed to pass through the lens.
The working aperture range is generally determined by the lens:
commonly somewhere between f/1.4 and f/22.

31. Aperture
Further, every time an f-number is halved (e.g. f/2 / 2 = f/4), the
resulting f-number has a fourth of the aperture area, hence a fourth
of its relative light.
LARGE APERTURE
SMALL APERTURE
AREA
F-NUMBER
f/1.4
f/2
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22
RELATIVE
LIGHT
256x
128x
64x
32x
16x
8x
4x
2x
1x

32. Aperture
Consequences?
Depth of field.
Depth of field (DOF) refers to the distance between
the nearest and farthest objects in a scene that
appear acceptably sharp or focused in an image.
Small apertures produce larger DOFs, while large
apertures produce smaller DOFs.
DOFs are also affected by focusing distance. The
closer the subject you’re focusing on, the narrower
the DOF becomes. Focusing to greater distances
(hyperfocal distance) makes the differences between
small and large aperture DOFs negligible.

33. Aperture
SMALL APERTURE
LARGE APERTURE
Larger DOF with more of the scene in focus, but Smaller DOF with less of the scene in focus
produces less light for exposure.
(appears blurry), but produces more light for
exposure.
Use smaller apertures (f/22 - f/8) to capture
sharper images. This is especially useful for
image compositing (easier to match blur
profiles).
Use larger apertures (f/5.6 - f/1.4) to create
emphasis and isolate subjects from the
background.

34. Aperture
HOW DOES DEPTH OF FIELD WORK???
A lens can precisely
focus at one distance
at a time. On each side
of that point, sharpness
decreases gradually and
imperceptibly. The DOF
limits are defined when
the “circle of confusion”
(a perceptibly blurred
point) becomes
apparent.
POINT
IN FOCUS
DOF
POINT
IN FOCUS
LENS
APERTURE
FILM/SENSOR

35. Aperture
HOW DOES DEPTH OF FIELD WORK???
Because light rays
projected through a
smaller aperture are
relatively more parallel
to each other, the DOF
is greater because
points are rendered
acceptably sharp in the
film or sensor.
POINT
IN FOCUS
DOF
POINT
IN FOCUS
LENS
APERTURE
FILM/SENSOR

36. Lighting
Think: an aerator or other flow modifier

37. Lighting
Lighting is in essence all the other non-camera, non-lens, non-film
techniques you can do to affect exposure. Some of these include:
BLOCKING
ADDING
INTENSIFYING
MODIFYING
Eliminating
light sources
completely or
partially, like
using flags to
control light spill.
Introducing new
light sources
or redirecting
more light into a
scene, like using
flashes or bounce
reflectors.
Manipulating the
amount of light,
like using neutral
density filters.
Changing the
apparent size and
character of light,
like diffusing it or
concentrating it.
More on lighting in the Lighting Basics Lunch & Learn.

38. Determining
the right exposure

39. Exposure
EXPOSURE MODES
There’s three ways to determine exposure in a camera:
AUTOMATIC
Camera does
everything for you.
SEMI-AUTOMATIC
MANUAL
You control certain
settings, and the
camera determines the
rest for you.
You determine all of the
settings.
These can be selected using the camera’s mode dial

40. Automatic exposure
AUTO
Automatic exposure is determined using the camera’s built-in light
meter, which measures the light that is reflected by a scene.
The other automatic modes (in the example above: sports, portrait,
night, landscape, macro), are an attempt to “set the camera in the
right direction” in case AUTO by itself isn’t giving good results.

41. Semi-automatic exposure
Av or A, Tv or S, P
Semi-auto is often the mode of choice, since you get to input what
matters for you (e.g. slow shutter), and the camera does the rest.
It’s having your cake, and eating it too.
• Av: Aperture Value, or Aperture Priority
• Tv: Time Value, or Shutter Priority
• P: Program, essentially AUTO but with exposure compensation

42. Auto and Semi-automatic exposure
HOW DOES BUILT-IN METERING WORK???
Metering works by averaging the luminance determined by the
metering mode and trying to approximate it to middle gray, or
18% gray. The most common selectable metering modes are:
CENTER-WEIGHTED
Evaluates 60-80% of
the scene, feathered
towards the edges.
The default.
PARTIAL or ZONES
10-15%, feathered,
based on the camera’s
focus zones or
evaluative matrix.
SPOT
1-5%, centered and
feathered. Used when
re-composing.
AVERAGE
Averages the
luminance of the entire
scene.

43. Manual exposure
M or Manual
Manual is used by purists and hobbyists, or when using older lighting
equipment that can’t be synchronized with a camera.
There’s two commonly used ways to determine exposure manually
without using a built-in meter:
• External Light Meters: Much more precise than camera built-in
meters. Usually only used professionally, and generally outdated.
• Histograms: Graphs that show the luminance distribution of an
image.

44. Histograms
DEFINED:
Histograms show the frequency of pixels across a
tonal range, from black to white absolutes.
Histograms can be found in nearly all digital cameras (usually
through the info button when previewing an image). They’re a great
way to determine correct exposure, as well as the overall character
of the image:
• Key: Low-key, predominantly shadows; High-key, predominantly
highlights.
• Contrast: Low-contrast, a concentrated tonal range; Highcontrast, a spread out tonal range.

45. Histograms
SHADOWS
MIDTONES
HIGHLIGHTS
FREQUENCY
(# pixels)
0
255
Each pixel in an 8-bit depth image is a combination of red, green,
and blue values (RGB). Each of these colors can have a brightness
value between 0 (black) and 255 (white). The histogram shows
vertical bars that count the frequency of these values.

46. Histograms
UNDEREXPOSURE
Values are concentrated on
the shadows, and blacks are
clipped (dark tones are blocked
up).
“CORRECT” EXPOSURE
Values are more distributed.
Shadows and highlights taper
off at the edges, with little to
no clipping.
(Because of the spread, it’s a
high contrast image)
OVEREXPOSURE
Shadows are distributed across
midtones and highlights, and
whites are clipped (light tones
are blown-out).

47. Exposure
SETTING THE EXPOSURE
SHUTTER SPEED (1/8000)
Usually set through the
main dial.
APERTURE (f/5.6)
Usually set through the
control dial.
ISO (6400)
Usually set by pressing
“ISO” button, then using
the main dial.

48. Exposure
Main dial, shutter speed
Control dial, aperture

49. Some of the
other stuff

50. Focal length
DEFINED:
Distance in mm from the optical center of the lens
to the focal point when focused on a sensor.
The focal length of a lens determines its angle of view. This
determines how much the subject will be magnified.
A lens with a focal length about equal to the diagonal size of the
film or sensor format is known as a normal lens. Shorter focal
lengths are called wide-angle, while longer focal lengths are called
telephoto.
Further, prime lenses have a fixed focal length, while zoom lenses
have variable focal lengths (e.g. 24-105mm).

51. Focal length
WIDE ANGLE
NORMAL
TELEPHOTO
<20mm - 35mm
~50mm
80mm - >300mm

52. Focal length
HOW DOES ANGLE OF VIEW WORK???
The angle of view gets wider the closer the optical center is to the
sensor (creating a shorter focal length). A narrow angle of view,
on the other hand, “crops” part of the image, magnifying it in the
sensor.
WIDE ANGLE
OF VIEW
SENSOR
SHORT
FOCAL
LENGTH
OPTICAL
CENTER
NARROW ANGLE OF VIEW
SENSOR
LONG
FOCAL
LENGTH
OPTICAL
CENTER

53. Focal length
Consequences?
Perspective distortion.
If you’re framing a shot the same way with a wide
angle and a telephoto (you move closer to your
subject with the wide angle, move farther with the
telephoto), perspective is significantly different in
one and the other.
Wide angles exaggerate or stretch perspective.
Telephotos compress or flatten perspective.

54. Focal length
WIDE ANGLE, STRETCHED PERSPECTIVE
Wide angle stretches perspective, so objects
are rendered progressively smaller the farther
they are from the optical center. The distortion
is also strongest the closer the object is to the
optical center (giving it a fisheye effect).
(Image was shot at 24mm, close to the subject)
TELEPHOTO, FLATTENED PERSPECTIVE
Telephoto flattens perspective.
(Image was shot at 300mm, farther away from
the subject)

55. Dynamic Ranges
DEFINED:
Dynamic range is the luminance range that a
camera might be able to capture.
It affects exposure in that certain scenes might have a large
dynamic range that can’t be captured by a single exposure (like
an interior shot with sunny windows in it), thus rendering certain
areas of the image under or overexposed.

56. Dynamic Ranges
INTERIOR EXPOSURE
EXTERIOR EXPOSURE
Exposing for the inside blows
out the highlights from the
outside.
Exposing for the outside
underexposes the entire
interior.
Decreasing window intensity
using neutral density filters or
waiting for a darker exterior
would produce an acceptable
exposure.
Using flashes or strobes to
light the inside of the room
would produce an acceptable
exposure.
EXPOSURE COMPOSITE (HDR)
Alternatively, multiple
exposures (a “bracket”) can
be combined to create a
single image. High Dynamic
Range (HDR) composites
do this through automatic
tone mapping, or it can be
accomplished by using oldfashioned masking.