1. Understanding Exposure: Shutter Speed + Aperture + ISO
Photography
Understanding Exposure:
Shutter Speed + Aperture + ISO
Kam Mistry
July-2013

2. What you need:
Camera that has a manual mode

3. What is Exposure: Definition:
Exposure is the amount of light collected by the sensor in your camera during a single picture

4. What is Exposure: Light hitting the sensor Simple, right?
Generates the image

5. An analogy, please: And light as rain
Think of the camera senor as a bucket
And light as rain

7. Question: How do you know that you that you are correctly exposed?
Use the light meter

8. The light meter is built into your camera
Think of the light meter as being a temperature gauge – hot: over-exposed, cold: under-exposed, just right: correctly-exposed
Use the light meter to “guide” your exposure setting

9. So, how do I set the correct exposure setting?

10. Before I explain that, we need to understand three variables that make up exposure.

11. The Exposure Triangle:
Just kidding!

12. The Exposure Triangle:
Three parts: Exposure = ISO + Shutter-Speed + Aperture
Exposure = Shutter-speed + Aperture + ISO

13. Shutter-speed There is a curtain in-front of the camera senor
The length of time the shutter curtain is open is called shutter-speed
The “curtain” can be open for a long time (1s, 5s, 10s, 30s, etc.)
The “curtain” can be open for short time (1/60s, 1/120s, 1/500s, 1/1000s, etc,)

14. Shutter-speed Slow Shutter-speed (5s)
Fast shutter speed = less light – freezes a subject
Low shutter = more light – blurs a moving subject
Senor is exposed to light for a longer period of time

15. Shutter-speed Fast Shutter-speed (1/1000s)
Senor is exposed to light for a short period of time

16. Shutter-speed
Comparing Shutter-speed:

17. Aperture
Aperture is “the size of the opening in the lens when a picture is taken”
It’s located on the lens
The Aperture opening can be small = less light on the senor
The Aperture opening can be large = more light on the senor

18. Aperture Aperture is measured in ‘f-stops’
Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens
F16 very small opening – less light on the senor
F1.4 very large opening – more light on the senor

19. Aperture
Aperture controls the “Depth of Field” of the image

20. Aperture
Large Aperture (F2)

21. Aperture
Small Aperture (F16)

22. ISO ISO measures the light sensitivity of the image sensor
The lower the ISO number less sensitive the senor is to light
The higher the ISO number the more sensitive the senor is to light

23. ISO ISO Similar to Sensitivity 100 Newspaper Low 800 Sponge Medium
Analogy:
Pouring water on:
ISO
Similar to
Sensitivity
100
Newspaper
Low
800
Sponge
Medium
1600
Tissue paper
High

24. ISO
Low Medium High
No Grain Little Grain Grainy

25. ISO
Use low ISO when in “good” lighting situation (ISO 100)

26. ISO
Use high ISO when in “poor” lighting situation (ISO 1600)

27. ISO
Comparison

28. ISO Question: What ISO should I use? Am I hand holding the camera?
Is my subject moving?
Can I get away with Grain?

29. Recap: The Exposure Triangle:
Three parts: Exposure = ISO + Shutter-Speed + Aperture
Exposure = Shutter-speed + Aperture + ISO

30. Example:
Camera Simulator:

31. Where to start? Use the 4-4-4 rule:
Aperture: F4
Shutter-speed: 1/400th
ISO: 400
Adjust the exposure so that your meter is zeroed:

32. References
Book:
Understanding Exposure, 3rd Edition: How to Shoot Great Photographs with Any Camera by Bryan Peterson
Web:

33. Questions?