Get Your Priorities Right
Today’s cameras offer so many different modes, it can be hard to keep up. Shelton Muller explains…
For many years, SLR cameras have included automatic exposure modes for speed and convenience. At first, exposure automation was strictly aperture priority. Then, camera manufacturers started switching things and offering shutter priority as an option. Then came multi-mode operation, program modes and then multi-program modes. Aaargggh! What does it all mean? When should you use which – and how? This article will sort it all out and help you get your priorities right.
Automatic modes are very useful, but which one do you use, for which photos - and when?
Photographers in all fields – fashion, portraiture, photojournalism, and landscape – once had to set their exposures manually. They selected their aperture manually. Then, they set the corresponding shutter speed manually – or vice versa. Dependent upon which was their priority, they would personally set the other to correspond. In automatic cameras, the same principle applies – only the camera sets it up for you. It is for this reason that the word “priority” is used. The photographer needs to decide which of the two exposure mechanisms is the most important and upon which the photograph is most reliant. In other words, is the aperture or the shutter speed your priority? Set the one and the camera automatically and correctly sets the other.
So, when do you use either?
Aperture Priority.
For portraits in which depth of field is an important factor, naturally aperture priority auto would be the logical choice…
As its name indicates, aperture priority mode means that the aperture is the more important of the two mechanisms in the photograph you are taking. It is often indicated as “A” or Av” in your screen or on your camera’s dial. Aperture priority automation is applicable in portraits and landscapes particularly, but there are many more uses for it than that.
In portraits, it is best to eliminate depth of field. A wide aperture ensures that this is done and the shutter speed is rarely a problem as a fully open aperture almost always ensures a corresponding shutter speed that is fast enough to handhold, let alone place upon a tripod.
Landscape photography, on the other hand, is quite different with respect to aperture selection. For landscape images, photographers often prefer smaller apertures in order to ensure greater depth of field. For most landscapes, shutter speed is usually an irrelevant issue as the camera is often mounted on a tripod and the scene has little if any moving subject matter.
Shutter speed priority.
Shutter speed priority automation (often shown as “S” or Tv” on your camera) assumes that the photographer is placing greater emphasis upon the correct shutter speed setting for the photograph. Therefore, landscape and portrait photographers may not necessarily benefit to the same degree as sport and action photographers would with this kind of exposure automation. However, shutter speed priority can also work in the reverse, where slow shutter speeds are actually preferred. This is true if movement or blur is a deliberate creative inclusion. This could even include sports and action photography of course.
You can achieve the desired result simply by moving your settings until the desired combination appears. However, this is where camera manufacturers saw the light and embarked upon an entirely new beast altogether – Program Mode.
Program Modes
As with all automated exposure operation, the photographer must be willing to allow the camera to take over to some degree. The photographer needs to trust the technology to provide the correct corresponding setting of either aperture or shutter. However, with ‘Program’ mode, the photographer submits entirely to the camera to decide the best possible combination of both.
For this to take place, the camera’s technology is designed to provide the best possible aperture for depth of field and the best possible shutter speed for hand holding. The camera’s metering system gathers all the information about the brightness of the photograph, the ISO of the film loaded and perhaps even the lens or flash attached. It then provides the best combination of aperture and shutter speed possible according to its inbuilt parameters and sets these the instant you press the shutter release button.
Most programmable SLR cameras today offer more than one program option. There are program modes for portraits, program modes for action, program modes for still life, landscape, flash and many more. In these more exact modes, the camera is told by the user to be programmed for a particular style of photography and meet its demands for the right shutter speed/aperture combination. For experienced photographers, this is most certainly an overkill situation. For others – perhaps those not so experienced – it is heaven sent.
Exposure automation has taken the fear from SLR photography and opened its doors for many who would not otherwise consider purchasing and using an SLR. The ‘knobs and dials’ that once frightened potential SLR users are now simplified to the point where the photographer simply needs to decide which automatic mode to use. SLR cameras today are as point-and-shoot engineered as compact cameras, but with the advantage of through-the-lens viewing and metering. For these reasons, the technology is welcomed. However, as with all technologies, an understanding of the benefits is still required – and human input is vital. Cameras don’t take good pictures. People do.
Shelton Muller can be contacted via his website at www.photographybyshelton.com
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March 31st, 2007
This is the best explanation of shutter and aperture priority I’ve come across so far, especially for an amateur like me. Thank you