UNDERSTANDING EXPOSURE

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Home    Lesson Plans    #1: Understanding Exposure

What is Shutter Speed?

While Aperture is responsible for controlling how much amount of light passes through the lens, the Shutter Speed is responsible for controlling the length of time that the light is allowed to hit the camera's sensor or film. The shutter speed controls the amount of time that the shutter curtain is left open. The shutter speed gives you, the photographer, control over how motion is captured in your photograph. Shutter speeds that are faster than your moving subject will create a photograph of your moving subject in a 'frozen' state. Your photograph will come out with your subject very sharp and in focus and seemingly in a stopped motion. You are basically capturing a split second image of your moving subject. If, on the other hand, your shutter speed is slower than your moving subject then you will create a blurred image of your subject which generally represents a subject in motion.

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How do we measure Shutter Speed?

Shutter speed is generally measured in seconds or fractions of a second. Below shows you a list of standard shutter speeds in full stop increments.

1/1000 sec
1/500 sec
1/250 sec
1/125 sec
1/60 sec
1/30 sec
1/15 sec
1/8 sec
1/4 sec
1/2 sec
1 sec
BULB

Note that some newer cameras allow you to set shutter speed increments in less than a full stop like 1/3 or 1/2 stop. Another important note - your camera's viewfinder may show the shutter speed as whole numbers. For example, it might show 500 or 250 but what it actually means is 1/500 or 1/250 seconds.

The example images below shows illustrations of the effect of shutter speed on the exposure of the photo. In this example, the ISO and aperture remain constant to isolate the effect of shutter speed on the exposure of the photograph.

Shutter Speed Effects
Figure 1: Effects of Shutter Speed on Exposure

In the photos above, the photo taken with shutter speed of 1/250 sec has the correct exposure. Do you notice anything diferent about the photos taken when the shutter speed was increased or decreased? Adding more time for the shutter to open while maintaining the aperture and ISO tends of overexpose the photo. If, on the other hand, the shutter speed is much faster, the photo will be underexposed.

Shutter Speed and Motion Blur

In the previous page, we discussed the unique effect of Aperture on your photograph which is Depth of Field. Shutter Speed also has the unique effect on a photograph and it has something to do with representing motion in a photo.

Shutter Speed allows you to either freeze movement or blur movement. If you set your shutter to open for a relatively long time, anything that is moving in your scene will cause motion blur in the image. If your shutter is open for a really short duration (split second), whatever is moving will generally become frozen.

The sample images below shows photos with different shutter speeds.

Shutter Speed and Motion Blur
FIGURE 2: Conveying motion using Shutter Speed

Notice that the photo taken with the slower shutter speed (1/60 sec) has the most amount of blur. The photo conveys movement or flow of the water. The photo taken with a fast shutter (1/1000 sec) speed has the effect of 'freezing' motion.

The aperture varies between the two photos in the above example. If you allow less time for the light to hit the sensor, then you need to adjust for a larger amount of light to pass through the lens to get a properly exposed image. This is the relationship between the shutter speed and aperture.

Keep in mind these general rule of thumb:

  1. Double your shutter speed for each full-stop decrease in f-stop
  2. Halve your shutter speed for each full-stop increase in f-stop

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Watch out for Camera Shake!

Motion blur can sometimes happen to a photograph even though the photography did not intend it to happen. This is unintended motion blur is caused by camera shake when holding the camera. As a general rule of thumb - to prevent camera shake when hand holding the camera, make sure that the shutter speed is greater than or equal to "1/focal length" of your lens. As an example, say you have a 60mm prime lens. To prevent camera shake while hand holding the camera, your shutter speed must not be slower than 1/60 sec. If you have a wide angle lens, say a 15mm lens. Your shutter speed must not be slower than 1/15 sec to prevent camera shake when hand holding the camera.

Camera Setting: Shutter Priority Mode

Shutter Priority Mode Dials

Shutter Priority Mode is a setting on your camera that allows you to choose a specific shutter speed value while the camera selects an aperture speed to match. Learning to use shutter speed properly allows you to create dramatic and creative photos.

The Shutter Priority Mode is usually represented by a Tv or an S on your camera dial. See illustration on your right. Consult your camera's product manual if you are unable to find the setting for Shutter Priority Mode.

  • It's time to tinker with your camera! This time, take a few minutes to figure out the Shutter Priority Mode setting on your camera. Become familiar with it and then set your camera to Aperture Priority Mode. Consult your manual if you do not know how.

Assignment 1.2: Get familiar with Shutter Speed

For this week, I would like you to spend time getting familiar with shutter speed. I want you set your camera to Shutter Priority Mode. Our goal for this assignment is to learn and see for yourself what the effect of varying shutter speeds on your photos. I want you to convey 'motion' on your photo. I want you to be able to freeze a moving subject in your photo. Experiment... discover... this is the only way to learn.

Assignment Instructions

  1. Set your camera to Shutter Priority Mode
  2. For this (indoor) exercise, set your ISO to 800 - 1600 depending on the light condition inside your home. Check your camera's manual if you do not know how to set the ISO.
  3. Find a faucet and turn on the water.
  4. Set your your shutter speed to the lowest time it would allow while still getting a proper exposure. Set it to 1/60 sec or less.
  5. Take a picture of your moving subject, the flowing water.
  6. Now, change your shutter speed setting to say, 1/1000 sec and take a picture of your subject again.
  7. Lastly, download your photo and view it on your computer. What's different about the 2 photos you took? How does the shutter speed affect the photo?

Project 365 or 52 Week Project for the serious hobbyist

If you are really serious about learning photography then I highly recommend that you try Project 365 or 52 Week Project. Both of these projects are great ways to practice and learn photography. For more detailed information about these projects and how to start, read my Project 365 or 52 Week Project blog. I have carefully organized a Weekly Theme Suggestions for this project to coincide perfectly with our step by step Lesson Plans.

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