10 -12 photographs
You need the camera to be fixed in front of something that moves several times or continuously across your view. Water flowing over some rocks is one possibility, or a friend riding a bicycle a number of times in front of the camera. The subject and setting of the image above is a good example. Try and think of something by yourself but make sure that the setting – and in particular, the background – is simple and plain.
Set the camera on a tripod, if you have one, so that the flow of movement is across the view. If the subject is someone walking or riding, their image should fit just within the viewfinder frame. Make a series of exposures, from the fastest shutter speed on your camera to a very slow one, such as one second. Adjust the aperture each time, or have the camera set so that it automatically adjusts the aperture (see its instruction manual) so that the exposure stays the same, as in the last exercise. Keep a note of the shutter speed used for each frame. Compare the finished images and mark each one with the shutter speed that you used. Find the slowest shutter speed at which the movement is sharply frozen. With some kinds of movement, like a person walking or cycling, there will be different rates of movement at the same time: the bicycle, say, will be moving at one speed, while the legs may be moving faster. You should be able to see this, too. Make notes about each print in your learning log.
This exercise required me to take a series of images of a moving object at differing shutter speeds, I went to quite a few different venues before selecting the images I used for this exercise, I had taken and was set on using a series from my trip to Purford lock of the water flooding into the lock as it was operated by the people with their long boats, it was a chance trip to Bird World with my oldest daughter that gave me the final inspiration for this fountain which has a much more consistent shape for comparison with this exercise.
My first image was taken at 1/250 sec which is mostly fast enough to freeze the motion of the water:
The Final image was taken at 1/4 sec shutter speed you can dramatically see the difference between the two ends of the exercise the water is in motion and has blurred to a soft white foamy appearance while the surroundings remain in focus, this image gives much more of an impression of motion you can no longer pick out the individual droplets of water.
Looking at an image that is in the middle of the range at 1/50 sec shutter speed you can see a combination of both traits it is possible to pick out the droplets of water but they are blurred with motion this image gives an impression of rapid motion of the water while retaining some of the definition and shape of the individual parts of the water:
The next nine images show the rest of the sequence 1/160 sec, 1/125, 1/100
1/80sec, 1/40sec, 1/20sec
1/30sec, 1/10sec, 1/6sec
Looking at each image I think I prefer a slower shutter speed the higher speed shots look a little false as the human eye when looking at a fountain like this does not freeze the action in this way so I think som blur is preferable I think the 1/50sec shot looks more the way I remember the scene so more life-like, but artistically I love the more unnatural angel hair like quality of the slower shots.
If I were to pick a shot for realism it would be the 1/50sec but my personal favourite is 1/4 sec as I love both the shape and the soft nature of the water.
Clearly Shutter speed is a key consideration in the set up and composition of an image. at its basest level shutter speed controls the time window in which the camera captures the photons bouncing off our subject, if our subject is stationary such as a rock or building the more photons that are reflected into the camera the more the image is exposed so too slow a shutter speed would make too much light enter the camera and thus over expose the image the reverse is true for too fast an exposure that would result in a dark or under exposed image, This has to balance withe the elements of the last exercise the aperture which opens and closes the lens allowing more light or less light to flow in to the camera, much as a bigger pipe used at the same pressure as a smaller pipe would take less time to fill a swimming pool with water. In our still example of the rock or building our concern is for a correct exposure in the amount of light, as we will see in the next exercise this is not our only concern there is a case where the correct amount of light where the shutter speed and aperture balance do not necessarily make a harmonious image. This is where we add motion to the mix.