Motion blur can be a photographer's worst enemy or best friend. The key is learning to control it.
Motion blur occurs when the camera's shutter speed is too slow to freeze motion of the camera or subject. There is no perfect shutter speed to freeze motion -- it all depends on the speed and direction of the movement, distance of the subject from the camera, and the focal length of the lens you are using.
In the early days of photography, portrait photographers always used a tripod, and quite often their subjects had to have their head movement restrained by a clamp in order to allow exposures lasting a number of seconds or even minutes. With faster film, and now digital, hand-held shots of moving subjects are quite possible without introducing motion blur.
Motion blur of the subject is most noticeable when the movement is across the frame, close to the camera, and with a longer lens. Conversely, distant movement towards or away from the camera and with a wider lens is less noticeable.
One of the hardest subjects to photograph without motion blur is close-ups of flowers when there is a breeze. Here, other than restraining the flowers' movement, the only solution is a fast shutter speed and lots of exposures in the hope of getting one when the wind slows.
Avoiding Motion Blur
Achieving a faster shutter speed typically requires you to use a wider aperture and to increase your ISO, both of which impact your image in other ways. A wider aperture (lower number) will reduce your depth of field, or range of distance from the camera that's in focus. An increased ISO will tend to introduce digital "noise."
Adding natural or artificial light also gives you greater flexibility to increase your shutter speed.
While camera movement can be avoided by using a tripod, or resting your camera on a stable object, this isn't always possible. Traditionally, the rule of thumb for the speed at which you could hand hold shots was based on the number of millimeters in the focal length of your lens.
This means that a shutter speed of 1/60 second or faster was required for a 50mm lens, whereas you could get away with 1/30 second for a 28mm lens. A 200mm telephoto, however, required a shutter speed of at least 1/200 second to avoid introducing blur from the camera's movement.
Crop Factor
This "reciprocal" rule of thumb for hand-held shots has been changed somewhat with the advent of smaller APS-C sensors on many consumer-level DSLRs, which introduce a "crop factor." Thus, on many digital cameras, a 50mm lens produces an image covering the area that a 75mm lens would cover on a 35mm film camera or full-frame digital camera.
This means your 50mm lens requires a shutter speed of at least 1/75 second, and your 200mm lens, which covers the same angle as a 300mm lens on a full-frame camera, needs a shutter speed of at least 1/300 second.
Image Stabilization
The other game changer is the advent of image stabilization in cameras and lenses. This is technology usually built into the lens, but sometimes right in the camera, that compensates for the camera's movement and reduces or eliminates motion blur. Different manufacturers use different initials to identify lenses with this technology: on Canon it's IS, on Nikon it's VR; Sigma calls it OS; Tamron calls it VC, etc.
With an image-stabilized lens, you can often hand hold your camera at speeds up to four stops slower than traditionally possible. For example, with my Tamron 17-50mm, it is quite easy to hand hold shots at 50mm at 1/8 second, and I have often achieved stable hand-held shots at 1/4 second.
Using Motion Blur to Show Movement
Often motion blur is desirable to show movement in your subject. Common examples are panning shots to show the movement of a runner or a car, night shots showing movement of car taillights, or images of waterfalls where the movement of water appears soft and silky. These techniques are dealt with in greater detail in other articles here, but the following tips should help.
You usually want your camera to be still so that a moving subject shows against a sharp background, and for this, you generally need a tripod. An exception is panning, when you want to follow the movement of your subject by moving your camera so that the subject is sharp and the background shows motion blur. Here a monopod or pivoting your body works better.
Neutral Density Filter
For outdoor subjects such as waterfalls in daylight, you will often find that you cannot slow the shutter speed enough to produce the motion blur you want. Setting your ISO to the lowest possible, and closing down your aperture (using a higher number) will help, but often this isn't enough. A neutral density filter is the answer. This grey, transparent glass or plastic filter goes over your lens and darkens the image by several stops, allowing you to reduce your shutter speed. Note that a circular polarizing filter will also darken your exposure by one or two stops.
A great way to show motion in low light is to use a flash, but "drag the shutter." This means you use a slower shutter speed than the normal minimum sync speed for flash of 1/60 second. Your subject will show motion blur due to the slow shutter, but the flash, which occurs in milliseconds, will add a second sharp, blur-free exposure of your subject. To achieve the most natural looking result, with the blur behind the subject, use second or rear curtain sync.
When it's uncontrolled, motion blur has ruined many photos. When you learn to control it, and make it your friend, you'll get more exciting photos that seem to come to life.
Join the Conversation