1. The document discusses various aspects of exposure in photography including the exposure triangle of aperture, shutter speed, and ISO. 2. It describes how aperture, shutter speed, and ISO affect the amount of light that reaches the camera sensor and therefore the exposure and brightness of the photo. 3. Metering modes, exposure compensation, histograms, and tools like zebra patterns are covered as ways to measure and help achieve proper exposure.

1. Lecture 3: Exposure
For beginners
By
Dr. Mostafa Hassan

2. Exposure What is Exposure
Exposure triangle
iso, shutter, Aperture
How the digital cameras see the exposure
Metering modes in digital cameras
Exposure Tools (zebra, false colors,
Histogram, wave form
Exposure modes in cameras
M,A,S,P

3. What is EXPOSURE IN PHOTOGRAPHY?
Exposure is the foundation of and one of the most important basics in photography.
Understanding what is exposure on a camera and how photography exposure works are the first
and fundamental things you need to learn when taking your first steps in digital photography,
and it’ll be the key to being successful when you start shooting in manual mode.
In this exposure photography guide, you’ll find exposure made simple. Not only are the basics of
photography exposure explained but also examples are given so you can learn, practice, and
have the perfect exposure on your photos.

4. EXPOSURE DEFINITION:
Exposure in photography can be
easily explained as the amount
of light collected by your camera.
When the light passes through
the camera lens to the camera
sensor for a determined period of
time, the amount of light that
reaches the camera will
determine the final look of the
image.

5. Correct exposure
The main effect of photography exposure is
to capture the image with a determined
brightness. When you shoot a perfectly
exposed photo, you are capturing all the
details in the highlights and the shadows
The exposure effect when the camera
sensor doesn’t receive enough light is
called underexposure.
In contrast, the exposure effect when the
sensor captures too much light is
called overexposure

6. WHAT IS EXPOSURE VALUE?
THE BASIC PHOTOGRAPHY
EXPOSURE SETTINGS
Exposure is not applied through a series of
rules, but, rather, through three basic settings
that are the key for understanding exposure in
photography and learning how to master
exposure in your images.
Exposure value is the result of the interaction
of the three main exposure
basics: aperture, shutter speed, and ISO. It’s
measured by the light meter

7. EXPOSURE AND
APERTURE
In a few words, aperture is the opening that determines how much light
passes through the camera lens to the sensor.
For this reason, exposure and aperture are completely related. If you use a
wider aperture, the camera lens will allow more light to reach the camera,
and the image will be brighter (more exposed). If, conversely, you close
down your aperture and block the amount of light that passes through the
lens, the image will be darker (less exposed).

8. Expose using A
Notice Increasing the F: No reducing the
aperture opening and vice versa

9. Aperture movement

10. EXPOSURE AND SHUTTER SPEED
Shutter speed: is the length of time
that the shutter of the camera
remains open, collecting light
Exposure and shutter speed are also
directly correlated. The longer you
leave the shutter of your camera
open capturing light, the brighter the
image will be, and the quicker the
shutter is opened and closed, the
less light will hit the sensor, which
will result in a darker image

11. Shutter speed and
sharpness
Your shutter speed determines how blurry or sharp
your image is

12. Shutter movement again

13. Iso and exposure :
Iso: International Organization for Standardization
Asa: American Standards Association
*Both referee to the film or sensor speed but when digital became the dominant in photography
the ASA as a unit diminished
because America prefers always to be different all the world uses the metric system America
uses the imperial system

14. ISO in photography
can be explained as a way to increase the light
information captured by the camera sensor.
How?
By the setting that can change the brightness of the
image without physically changing the amount of light
entering the camera. It defines the degree of digital
amplification of available light hitting the sensor
that’s why when we increase the sensitivity of the
sensor the (digital noise increase)

17. Exposure Triangle

18. Balancing elements
When shooting in manual mode, the best tip to learn how to expose in photography is to think first about the settings that you need
according to the light of the scene and your photography goals. Normally, there are one or two settings that you’ll know in advance, and
then you’ll need to play with the other or two others to get a well-exposed photo.
For instance:
Are you shooting a landscape in broad daylight? You know that your aperture must be around f/11 to ensure a great depth of field, and
the ISO must be 100 to ensure that you have no digital noise, so the exposure adjustment to balance and get an EV of zero will be
the shutter speed.
Are you shooting a night scene? Your aperture will be the widest to capture as much light as possible (f/2.8) and the time will be 25
seconds in order to capture sharp stars and not trails, so the exposure adjustment to balance and get an exposure value equal to zero will
be the ISO.
Are you shooting a flying bird? To freeze the movement of the bird, you know that you need a fast shutter speed around 1/2000th of a
second and a low ISO to avoid digital noise (100), so the setting to balance the exposure and get an EV of zero will be the aperture in this
case.
These are just three examples, but there are more depending on each situation. My recommendation to maximize your exposure control
is to practice and shoot as much as you can in all kinds of light situations. At some point, you won’t even think about which exposure
setting you need; you’ll just set it automatically.

21. HOW TO MEASURE
PHOTOGRAPHY EXPOSURE:
THE EXPOSURE METER
Luckily, digital cameras have a built-in tool
called a light meter or “metering
sensor” that will help you measure the
exposure value of the image for the
selected settings. That way, you can adjust
them to get a well-exposed image.

22. Reading the internal light
meter

23. Exposure metering modes
To evaluate the exposure and calculate the exposure value (EV) through the light meter, digital cameras use
several metering modes.
The most popular exposure metering modes in photography are:
Matrix metering: This is the most popular meter mode and consists of an evaluation of the light across the entire
image. The frame is divided into multiple areas, and the exposure value is calculated according to the general
brightness to strike a balance between highlights and shadows.
This exposure metering mode is called Evaluative metering in Canon cameras.
Center–weighed metering: In this mode, the camera uses the center of the frame to evaluate the general
brightness and image exposure.
Spot metering: In the last mode, cameras uses a single focus point that you can manually adjust to measure and
calculate the exposure value.

24. Matrix mode

25. Center weighted

26. Spot metering

28. Exposure compensation
When you shoot in automatic (P) or semi-automatic (A) and (S) mode, or in manual mode with Auto-ISO, the
camera will adjust one or more of the basic exposure settings so that the exposure value is zero in order to get a
perfectly exposed photo, as we explain in our camera modes guide.
However, there are some light and color situations that are tricky to balance for most digital cameras, where an
exposure value equal to zero will result in an overexposed or underexposed image.
If, for example, there is high contrast in the image between whites and blacks, the light meter will try to make a
balance, but if one of the high-contrast areas is bigger than the other, the final image will probably be
overexposed or underexposed.
If you’re shooting manually, it’s totally fine, since you can decide to take the photo with settings that result in an
exposure value that’s different from zero. However, to solve this problem in automatic modes, there’s another
tool incorporated into digital cameras called exposure compensation.

30. Why the camera Auto
mode reads the
exposure wrong
Because light meters can only understand the
gray, and reads the correct exposure
18% grey because of how the gamma works
(we don’t want to go extreme techy here)

32. Exposure Tools (zebra, false colors, Histogram, wave
form
False color and wave form are exposure
tools used in cinema and tv (we will discuss
them later)
Histogram and zebra
Histograms can be found in almost any
camera and any modern image editing
software.
A histogram is a graphical representation of
the tonal values of your image. In other
words, it shows the amount of tones of
particular brightness found in your
photograph ranging from black (0 brightness)
to pure white (255 brightness)

33. Understanding
histogram

34. Zebra
Zebra Pattern is a camera feature that overlays some stripes onto the image that indicate
exposure levels. It is a function that aids exposure by showing a striped pattern over the areas
that are close to overexposure
To avoid a white object become dark (underexposed)
Set a Zebra setting between 90 and 95, and adjust the exposure so that the Zebra pattern
appears on the white subject you want to shoot.
To take a photo of people with optimised brightness
Set a Zebra setting between 70 and 80, and adjust the exposure so that the Zebra pattern
appears on the face of the subject.

35. How zebra works

36. !!! Applications
-If the correct exposure is at F: 2.8 shutter 1/50 iso 500
-Change the f No to 5.6 and deduct the shutter speed and iso
-change the shutter speed to 1/100 and deduct the F: No and iso
-change the iso to 800 and deduct the F: No the f no and the shutter speed