Exposure in Detail

On the basics page the shutter speed or exposure time was described as the amount of time the camera lets light in.  We know the shorter amount of time we let in light the darker the picture will turn out.  What we want to concentrate on for exposure time is what effect on the contents of the picture will be.  Remember we can change the ISO settings on digital cameras at will, adjusting how light or dark a picture turn out is easy.

The primary factor of exposure time this article is going to cover is motion.  The faster your shutter speed the clearer your photo will be and less blur.  Remember dancing under a strobe light? Your eyes could only see for the short amount of time the light was on.  It would appear all motion was 
stopped. Fast shutter speed.  When you look out the side window of a car at 70 mph, the world is a blur. Slow shutter speed. The sample picture shows the fast exposure on the left, catches the individual drops of water.  The one second long exposure on the right makes the water appear to be long unbroken streams.  When shooting with a flash, an exposure of 60 (1/60th second) is standard.  If you are shooting with the camera in your hands and not on a tripod, you will want faster exposure times.  If you are shooting anything with action, you need faster exposures to prevent blurring.

Most cameras give the ability to freeze time with extremely fast shutter speeds of 1/3200 of a second or faster.  These high speeds were used to take the pictures of fire posted on this site. The far opposite is the bulb mode, in which you must manually close the shutter after minutes if you choose.  Bulb mode is used for night photography and special trick shots.

Move your camera's mode selector from 'Auto' to 'S'. This setting is usually referred to as 'Shutter Priority'. The camera will allow you to set the shutter speed manually while automatically setting your aperture.  This makes it easy for you to warp time in your pictures. Remember you must use a tripod with slow exposures.

Common uses:
Set your camera to one second (1") for:
    The classic 'fluffy' water fall.  Set your camera on a tripod focused on an area of splashing water in a stream.  The long exposure time will allow multiple splashes to blend into one, giving that 'fluffy' look.
    Long red lines of tail lights.  Set your camera on a tripod, looking down on a busy highway.  With a nice long exposure, all the cars will blur together and you will only see the path the cars took as a set of streaked red lines.

Set your camera to 1/2000th of a second (2000) for:  
    A crisp detailed look at the top of a cresting wave.  On a nice sunny day at the beach, use a fast exposure and tight zoom to catch the tiny droplets of mist peeling back off a toppling wave.
    Hummingbirds.  I am not an ornithologist, but I think hummingbird wings move somewhere near the speed of light. If you want to see the beauty of this delicate creature, you need a fast shutter. (And a bit of luck)