Here we have an interesting variety of images that utilize a motion blur effect in very different ways. In the first image, a slower shutter speed is employed in order to capture the moment of a weightlifter at work, with the motion blur enhancing the effect of the physical action. In the second image, we get a sense of chaos from the motion of lottery balls colliding with each other. The last photo is the slowest shutter speed example we’ve shown so far, since the photographer was attempting to capture star trails.
Motion Blur vs. Camera Shake
Camera shake is technically a form of motion blur, but not all motion blur is due to camera shake. In fact, camera shake is the least desirable form of motion effect in photography. You’ll see it a lot, but you’ll rarely see it done on purpose.
You may be thinking to yourself, “Good thing I don’t have shaky hands!” and we really hate to burst your bubble on that. But no matter how steady-handed you are, leaving your shutter open for a longer time (even by a few fractions of a second) while holding your camera will almost definitely result in camera shake. That’s why it’s advisable to use a tripod once you get around or below 1/125th of a second, even if you’re intentionally trying to capture motion. The idea is to get your effect from objects that are moving in front of your camera, not from the movement of your camera itself.
If it sounds like we’re being a little over the top with this, just give it a shot. Get into a low-light situation, open up that shutter to maybe 1/60 or 1/30, and see what happens. You may even find that a tripod isn’t enough! The action of your finger pressing the shutter button may still create camera shake with a long enough shutter speed. In this case, you’ll want to look for a remote trigger to get everything looking exactly right.
Don’t judge the crispness of your motion based solely on how it appears on the back of your camera. If you want a completely frozen effect, be sure to zoom in on the image preview or bracket your shutter speeds. Don’t let there be an unpleasant surprise waiting for you when you see it for the first time on your nice, big computer screen!
Balancing the Exposure Triangle
In our previous installment, “Understanding Aperture: Controlling Light Based on the Exposure Triangle,” we took an in-depth look at a variety of different ways that proper light exposure can be achieved by adjusting the camera’s aperture. This time, let’s consider some examples of how this balance can be achieved in relation to shutter speed.
A Note on Aperture
Aperture is the variable size of the opening in the lens when an image is being captured. It not only controls how much light enters the camera, but also determines the depth of field of an image.
Briefly stated, a wider aperture allows a great deal of light to reach the camera sensor, but will result in a shallow depth of field. A shallow depth of field basically means that areas of the image that are farther away from the point of focus will appear blurry, while subjects or objects nearer to it will appear crisp and sharp.
The opposite is true for a narrower (more closed) aperture. Less light will reach the camera sensor, but it will provide a wider depth of field. A wider (deeper) depth of field will keep areas of the image that are farther away from the point of focus looking sharper.
A Note on ISO
ISO (discussed in greater detail in our dedicated guide to ISO) refers to a camera sensor’s relative sensitivity to light, or in other words, its “ability” to capture light. The higher sensitivity setting you choose, the more light there will be available to you. Unfortunately, a higher sensitivity will also increase the amount of digital noise you should expect to see in your image.
A Practical Example
Let’s use an example to demonstrate how we might balance the triangle under a particular circumstance:
Imagine you have a subject you wish to photograph and you adjust your aperture to a wider setting, which provides you with a great deal of light. However, it also provides you with a shallow depth of field, and you’re not content with this as you wish for a greater area of the image to remain in focus.
You then adjust to a narrower aperture setting, which corrects your problem regarding the depth of field and image clarity. Only now, your image appears far too dark for your liking, and another adjustment needs to be made. But what do you adjust?
You remember that a slower shutter speed allows for more light to reach the camera sensor, so you adjust the speed down the scale to a longer exposure time. But in doing so, you’re also reminded that this allows for greater motion blur, and in this case, that simply won’t do.
You want to eliminate that undesired motion blur, so you adjust back to a faster shutter speed so that you can freeze your subject in time. But now the image is back to being a bit too dark.
This is where you turn to the third and final part of the exposure triangle: the ISO. At this point, you’ve achieved both a satisfactory depth of field and your desired amount of motion capture, but you still need more light. The solution here is to raise the ISO to a higher setting in order to increase the camera’s light sensitivity, achieving a brighter exposure without compromising on your depth of field or range of motion.
Below is an example of an image noticeably improved in quality by increasing the ISO level:
Tying It All Together
As we like to remind you, experimenting with the settings on your camera is part of the joy of learning photography. Shutter speed is particularly fun to play around with because of the dramatic difference you can get from just a small adjustment. Remember to practice balancing it with your aperture (and depth of field) and ISO to get a good overall exposure.
There is always more to learn and the journey is half the fun! So as you continue to explore and develop your craft, make sure to enjoy the moment and keep an open mind.