This is the second in a series of Intel and if you are familiar with the first couple of paragraphs, please just skip down to the start of the section on Shutter Control. This Intel for camera owners whose cameras have a series of letters on the dial, but have never been off the Automatic setting. By “Automatic setting” I mean both the “just point and shoot” position and also the so called “scene modes” that the camera maker labels with little icons for close-up (usually a flower), portrait (head), sports (running man), landscape (mountains) and the like. I have one camera with dozens of these scenes available, even down to settings for parties, snow and food!
Now, whether you set these by turning a dial or through a menu, they all work by altering just 5 settings in your camera: White Balance, Focus System, Shutter Speed, Aperture Value and Flash. Most cameras control White Balance even in manual mode: you have to choose to override it, so I won’t deal with it in this Intel beyond mentioning what each is.
White Balance adjusts for the colour of the light falling on it. It is the equivalent of human sight’s ability to see paper as white even if we turn off the fluorescent light and turn on the tungsten light…fluorescent is green, tungsten is red, yet the paper is still white to us.
Focussing Systems move elements in the lens until the part of the subject in the focusing area attain maximum contrast. They can operate in various modes, the main ones being “single shot” which locks the lens as soon as focus is found; “servo assisted” which continuously attempts to keep the lens focussed on the subject as it moves. Oter modes tend to be variations and combinations of these two.
Flash is offered on most cameras and usually includes settings to reduce red-eye (reflections from the retina of the eye), general flash and some modes to allow “night portraits”, where a flash exposure to record the foreground is followed by a longer exposure to capture the darker background. Most cameras will also allow the flash to be disabled, and some cameras with a particular type of shutter will also allow you to choose whether the flash fires as the shutter begins to open, or as it closes.
The most important control, however, are the Shutter Speed and Aperture settings. Understanding these two aspects of photography marks the difference between a snap-shooter and a photographer.
Having covered aperture control in previous Intel, I’m going to take a look at the other main exposure control - shutter speed. As well as affecting exposure, shutter speed can also be adjusted to produce a number of amazing effects – it can even let you control time!
Shutter priority mode (usually ‘S’ on the mode dial) is a semi-automatic exposure mode in which you set the desired shutter speed, and the camera’s exposure system then sets the appropriate aperture to produce the correct exposure.
As pointed out elsewhere (see Pinhole Camera Intel) a camera does not have to have a lens. Nor does it need a fancy aperture: a box camera lets the light through a neat hole of fixed size. But without a shutter you just don’t have a working camera.
Most cameras have a shutter located just in front of the film or in the lens if the camera has a non-removable lens. In-lens shutters are “leaf” shutters, with leaves that open like a diaphragm to admit light. Larger format professional cameras also locate the shutter in the lens, so that each lens has its own shutter with specific shutter speed progressions.
Single lens reflex cameras have focal plane shutters. These work by having two blinds, one protecting the sensor or film from light until you take a picture. This blind then moves across the sensor, either vertically or horizontally, quickly followed by the second blind. A small gap between the two moving blinds lets light reach the sensor. The speed at which the second blind replaces the first and the width of the gap determines the shutter speed.
The shutter is just a mechanical barrier to prevent light from falling on the film or sensor until it is needed. When a picture is taken, the shutter is opened for a precisely measured amount of time determined by the camera’s light meter or your judgement depending on the amount of light and the aperture setting.The flash on your camera is timed to coincide with the gap between the two blinds.
Shutter speeds are a lot simpler to explain and understand than aperture settings. Shutter speeds are measured in seconds, and each setting is twice as fast (or slow) as the next. A typical shutter speed progression might look like this: 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60 … all the way up to 1/1000 or more.
Cameras have a range of shutter settings from seconds to thousandths of a second. Some can go as high as 1/8000th of a second, some can time a shutter release as long as 30 seconds and many also have a feature called a ‘B’ setting, in which the shutter stays open for as long as you hold the shutter release down ( ‘B’ stands for the air ‘bulb’ once used to work a remote shutter release); and a few even have a ‘T’ setting in which the shutter opens when the shutter release is pressed and stays open until it is pressed again.
If you let the camera control shutter and aperture (auto) your shutter speed will usually be set to between 1/125th and 1/1000th of a second, since the camera assumes your aim is to freeze most movement and to reduce the effects of camera shake.
As a rule, camera shake will not be a problem, even if you do not have an anti-shake system in your camera, until your shutter speed falls below the focal length of your lens. For example if you’re using a 100mm focal length (a typical 3x zoom compact at full telephoto is equivalent to 105mm) then you can take a sharp hand-held shot at a shutter speed 1/100th of a second or faster. If you’re using a 35mm focal length then 1/35th of a second is safe, and so on.
Anti shake systems can only steady your hand, not your subjects. Movement in the frame will be captured in the picture, resulting in motion blur. The solution is to choose a shutter speed fast enough to effectively stop the action.
With a fast enough shutter speed you can freeze even very fast-moving objects: the wings of insects, a drop of water striking a plate, a racing car or a thrown ball. But sometimes you might want to allow a degree of movement to show that the subject was in motion. In Shutter Priority you have several ways to accomplish this.
Panning is a technique which uses a slow shutter speed to emphasise fast motion. Set you camera to Tv and hold your subject in center frame (say a car) as it moves by. By “panning” the camera (moving it side-to-side) to follow the moving subject as you press the shutter, you will capture a sharp image against a blurred background. This works because the camera and subject were moving at the same pace in the same direction – motionless relative to each other, but not to the background. It is a technique that requires a bit of practice, but once you’ve got it, the results are very effective.
Creamy Water One of the most popular uses of long shutter speed is photographing flowing water. It works with anything where there is white splashing water, even a hose! If you just point the camera and shoot, you’ll end up with a picture that looks lpretty static. But set the camera on a tripod and set the shutter for 3 seconds and you have fairyland!
Fireworks can be taken in a similar way. Set your camera on a tripod some distance from the display. Don’t zoom in too close and set a shutter speed of two seconds or more. Point the camera at a part of the sky where the fireworks are dense, wait for the start of a launch and press the shutter. With a bit of luck, you will get several bursts in the one frame.
To boost the odds in your favour, set the shutter on ‘B’, hold a piece of card in front of the lens and hold down the shutter release. Every time you see a good burst in the part of the shy you are trained on, take the card away, then cover the lens again without letting go of the shutter release. When you have 4 or 5 nice fire-blossoms on the frame, let go of the button.
Light Trails Three sources of light become really interesting with long shutter speeds:streaking car lights at night, which are taken just like fireworks. With the camera on a solid support (preferably a tripod with a cable release) take a series of shots at several different shutter speeds, starting at four seconds and increasing by two seconds per shot. Bracketing exposures like this is the best way to ensure a good result.
Star Fields are captured the same way: a heavy tripod pointed at the heavens on a clear night well away from man-made light. Here, however, the exposure is measured in hours!
The third in this group is light patterns abstracts: place the camera on the floor below and just off centre from a light bulb swinging from the ceiling. Set the camera to 30secs, turn out the other lights, start the light bulb swinging and when it settles into a nice smooth pattern, trip the shutter button.
Two other very useful attributes of shutters: at high speed they allow us to examine objects in amazing detail, and in burst mode we can gain a quite new understanding of movement. Of course, the other value of burst mode (or continuous shooting) is that you are more likely to capture that fleeting moment where reflexes are not enough.
You want to catch that bird on the fence as she takes off, but you have been off just that much; hesitating a moment too long or firing too soon. Set continuous shooting and a high shutter speed, As soon as you detect the chance she might be off, hold down the shutter. Depending on your camera you will get anything from 3 to 11 frames per second and a great chance that one will be the very one you were after. What is more, at say 1/1000 of a second, you will see every detail.
I said you can control time through the shutter, and these technique do do that; but absolute mastery comes with time lapse photography. Choosing to place the camera in the exact spot at the same time every hour, or every day and exposing the same picture, then playing them back as if shot in a movie or video is the way those wonderful features of growing plants and the like are made.
In the third of this series I want to look at exposure compensation and the Program (‘P’) setting. By that time you should be totally confident with getting that camera off auto and onto Tv.
