In the first segment of the new Photo Basics series, we took a look at the role of the aperture. In this segment, we’ll look at the shutter and how it can be used for controlling action and movement within your images.
In combination with the aperture and ISO setting, the shutter forms part of what I refer to as the ‘exposure triumvirate’. That is, it’s one of the three components that work together to make up the overall exposure of your photos. We’ll look more at this in future instalments.
The shutter speed controls the amount of time the shutter curtains are open and how much light hits the film or sensor as a result. Modern SLR-type cameras have curtain shutters. Two metal or carbon fibre overlapping curtains that open and close in succession. With moderate to slow shutter speeds one curtain opens, exposing the sensor or film to light then the second curtain closes cutting off the light exposure. At higher shutter speeds the second curtain will begin to close before the first is fully open. This creates a slit that moves across the sensor or film. Another type of shutter that’s common in medium and large format cameras is the leaf shutter. In this type of shutter a set of blades in the lens opens and closes for the prescribed time. This difference in shutter types will be more important in a later instalment when we examine the basics of flash photography.
The shutter speed helps us control action. Faster shutter speeds help us stop action and slower shutter speeds will give blur or motion to action.
In a static scene, such as architecture, where there is no action or movement the shutter speed doesn’t really matter and can be set at anything, relative to the aperture and/or ISO setting desired.
When we have a subject or scene with movement; however, the choice of shutter speed becomes much more important. Do we want to freeze the movement or allow it to blur slightly to give a sense of motion? It depends. Sometimes freezing movement is the way to go and sometimes not. In many sports images, we see sharp, frozen images most often. The action in the play at the time the shot is being taken lets us know there’s movement going on. Sometimes though, it can be preferable to allow a bit of motion blur into the shot. A racing car on the track, for example can be given a sense of dynamism with a bit of blur – often in the wheels.
Let’s look at some examples.
This first shot was taken at 1/200 sec. We can see the wheel rotation is blurred which is good but other parts of the shot are blurred as well. The writing on the car isn’t as clear as it could be.
This second shot was made at a shutter speed of 1/400 sec. We still have motion blur in the tires but the writing on the car is clearer. The blur in the driver’s helmet is less as well. Still not quite where I’d like it though.
In the third shot a shutter speed of 1/800 sec was used. We still have the motion blur in the wheels but the rest of the car is quite clean and crisp. This is what I was looking for in this shot.
Let’s take a look at one more.
In this last shot, a shutter speed of 1/1000 was used. As we can see, the rotational blur in the tires is much less and, in my opinion, not enough. The rest of the car is still crisp but we’ve gone a bit too far with the action freezing of the shutter speed. If we get too fast with the shutter speed and freeze the action too much it would look like a staged shot taken on the track with the car sitting still. If there were more background in the shot to show the panning action of the camera and the background were blurred, this shot could work because we’d get the sense of action and movement from the blurred background. In this case I wanted a close up on the car so needed more movement in the car to convey the sense of action in the shot.
For a point of reference, the car, at this point on the track was coming off a slow hairpin curve, accelerating quickly and moving at about 130 km/h (80 mph). I was about 30 feet away shooting at ISO 160, 300mm and f4.
Let’s take a look at a much slower form of action.
Here again we’ve got an isolation shot. There’s no other action in the frame to give a sense of movement. If I’d shot this with a fast enough shutter speed to freeze the stick it would, again, look like a staged shot. Using a shutter speed of 1/500 sec I was able to get the player’s head and body stopped but have a bit of blur in the stick at the bottom of the shot. The bend in the stick also helps convey action.
This image, taken at a shutter speed of 1/400 sec freezes the action much more because the movement in the shot was much slower. In the full size shot you can read the writing on the puck quite clearly. Even though the movement is frozen, because there’s more going on in the scene we know that there’s action and movement. The puck being off the ice helps tell us that this isn’t a staged shot as does the position of the goaltender and the checking from the opponent player on the puck carrier.
The shutter speed can also be used creatively to enhance movement. A classic example of this is the silky, flowing water look. This is achieved by using a slower shutter speed (sometimes many seconds) to smooth out and blend the movement. The shot below is an example. This was taken on medium format film with a shutter speed of 8 seconds. Similar effects can be achieved with wind movement and trees, flowers or grasses.
So, to come back to our earlier point, shutter speed controls action. You’ll need to do some testing in your specific situations to determine what shutter speed(s) you’ll need to get the degree of movement freeze you want. The LCD on the back of the camera can be very helpful in that regard particularly when you can zoom in on the LCD to take a close look at the image. Over time, as you shoot different situations and in different conditions, you’ll develop a sense of what kind of shutter speeds you need it a specific situation and won’t need to do as much testing.
If the shutter speed gets too slow, you may not be able to hand hold your camera and get a quality image due to camera shake. The standard rule of thumb for hand holding is that the shutter speed should be at least 1/lens focal length. So with a 100mm lens, your shutter speed should be 1/100 sec or faster. With a 24mm lens, your shutter speed can be 1/24 sec or faster. This is a guideline and not a hard and fast rule. Some people can hand hold at slower shutter speeds and still get a sharp image. Some can’t even go as slow as the guideline. Do some testing of your own to see what your limit is. Other features such as image stabilisation in the lens or the camera body also can allow us to get sharper images at shutter speeds slower than the 1/focal length guideline. But stabilisation isn’t a silver bullet. It shouldn’t be relied on to rescue you from a bad exposure because it won’t. And in lens or in camera stabilisation only compensates for camera movement, not subject movement. The better option, when shutter speeds are getting too slow to hand hold is to put the camera on a tripod. A monopod can be useful in some situations such as where panning is needed.
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