Notes on Shutter Speed
The more that you know about what the shutter speed of a camera means the more knowledge you have when you are looking for a used camera, whether it is a classic camera or a digital camera. The following points will give you a good understanding of what camera shutter speed is all about.
The shutter of a camera is simply a mechanical device that lets light come into the body of the camera for a certain amount of time. More light will enter the camera the longer the shutter is open.
SLR cameras (single lens reflex) will usually have a shutter that is mechanical, however electronics can get the same effect by clearing the camera image sensor and then letting the sensor collect the light for the specified amount of time. Inexpensive cameras will have this type of shutter.
Most digital cameras will have a setting that is automatic to determine the right speed for the shutter. As well, you can manually set the shutter if you want more control artistically.
The shutter speed is calculated in combination with the camera aperture. The aperture is the size of the lens opening. These two settings will be used in combination so that you can control how much light reaches the image sensor.
A shutter speed that is fast will "freeze" the action. You can use long shutter speed when the light conditions are low. This allows any moving objects to blur a bit. This is an effect that can be used when you are photographing water that is running.
Because a shutter speed that is fast lets in less light than a shutter speed that is long and slow, it is often used with a bigger aperture setting so that the right amount of light reaches the image sensor. As well, shutter speeds that are long can be used with small apertures.
The speed of the shutter is calculated in fractions of a second using a 2:1 scale, begining with one second. The scale runs as this: 1 second, 1/2 second, 1/4 second, and then all the way to the fastest speed which is 1/8000 second. As well, many digital cameras will come with a "B" setting for the shutter. What this means is that the shutter will stay open for as long as the button is pressed. A "T" shutter setting will cause the shutter to stay open until the button is pressed again.
Settings for the aperture are calculated using the same 2:1 scale that the shutter uses. This lets the same total amount of light exposure be used, thus increasing the speed of the shutter by one notch while at the same time opening up the aperture by a notch. The light conditions for any scene that you are photographing will allow for different ranges of aperture/shutter mixings. There isn't a right or a wrong combination since it will all depend on what effect you are hoping for.
If you want to capture a subject that is moving, such as someone at a sporting event, you might normally use a shutter speed that is fast so that you can freeze the action. You will have to use the fast shutter speed in combination with the right aperture so that you can expose the picture in the right way.
You might want to use a shutter speed that is slow if you want to pan the camera so that you match the athlete in motion. This effect will be more dynamic as some areas of the image (in particular the background) will be slightly blurred. A slow shutter speed needs to be compensated for with aperture settings that are smaller.
Yet another photo effect is achieved by controlling the depth of the field so that you highlight the subject. Apertures that are larger will have a depth of field that is smaller. This means that the background and the foreground of the image will be nicely out of focus. If you want to achieve this you need to combine a larger setting of the aperture with a shutter speed that is fast.
Adding flash to the picture will add another dimension to the shutter-speed calculation. You can get some interesting effects when you use the flash to freeze the main action while at the same time letting some of this action be blurred by using a shutter speed that is slower.
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