There are three settings that determine exposure - shutter speed, aperture, and ISO (film speed). Let's begin by looking at the first two, then we'll add in ISO later.
Let's start by looking at shutter speed. If you select Tv (time value) on your mode dial then you are most interested in controlling the amount of time that the shutter is open. This will generally be true for action shots where you want to freeze motion or artistic shots where you want to blur motion, as is common with moving water or water fountains.
Measuring shutter speed is relatively simple. Shutter speed is generally measured in fractions of a second. A shutter speed of "5000" means that the shutter will open for 1/5000th of a second. Shutter speeds of 1 second and longer are generally marked with a ', or other similar mark, after the number. This means that 16' on your camera's display would stand for 16 seconds.
Slow Shutter Speed
Shutter speed is considered to be "long" or "slow" when it is slower than 1/60th of a second. (Remember, this is marked as 60 on your camera dial or display). Most people can only hold a standard lens (between 35mm and 70mm) steady for 1/60th of a second or less. This is different from the commonly used term "long exposure" which usually refers to shutter speeds of over 1 second.
Fast Shutter Speed
Fast shutter speeds are generally considered to be those shutter speeds faster than 1/500th of a second. These shutter speeds are used to freeze or stop motion for a clear image when shooting fast subjects.
Rule of Thumb
A good rule of thumb for knowing the slowest shutter speed you can use with a particular lens, without using a tripod, is to use the number of the lens size. For example, a 300 mm lens can be hand held at shutter speeds of 1/300th of a second and faster. Note that the minimum hand held speed should never be below 1/60th of a second without image stabilization assistance from your camera or lens. If your lens does have OIS (optical image stabilization), you can use shutter speeds as slow as 1/15th of a second.
Here are some photography tips for shutter speeds in specific situations. The speeds listed are the needed speeds to freeze the action under normal conditions. If you want to blur the action, decrease the shutter speed. To adjust for a very fast situation, increase the shutter speed.
· Football - 1/400
· Baseball/Softball/Hockey - 1/350
· Kids Running - 1/350
· People Jumping - 1/250
· Golf Balls - 1/3200
· Water Splashing - 1/350
The process of exposure revolves around the concept of stops (or f-stops).
A stop is defined as doubling or halving any value.
2 things determine the exposure for any photo:
- The shutter speed – Length of time the shutter blades are open, allowing light to fall on the sensor. Expressed in seconds.
- The aperture of the lens – Measurement of the size of the lens opening when the shutter is open. Expressed in f-stop numbers.
They both work in the doubles and halves progression of stop increments.
If you change one you must change the other.
Analogy: You need to fill a bathtub. You can fill it very quickly with a large hose or very slowly with a small hose. Either way it gets filled with the same amount of water
Shutter Speed = how long the water is running
Common shutter speeds:
2', 1', 2 , 4, 8, 15, 30, 60, 125, 250, 500, 1000 (2 is 1/2 of a second, 8 is 1/8 of a second, etc)
Each shutter speed is half or double the one next to it, which is a 1-stop change
Autoexposure uses “stepless” shutter speeds – shutter can be set at any speed.
Faster shutter speed = image will appear more frozen in time
Slower shutter speed = blurrier image
You need bright light for fast shutter
You need low light for slow shutter
Use a tripod for slow shutter
For an easy to understand tutorial on the difference between aperture and shutter speed go to the SimCam.
For some great examples of how shutter speed can be used to capture great images, visit this Flickriver page.
Now that you understand shutter speed, you are ready to tackle the more complex subject of aperture.