It can be daunting and confusing to depart from your camera’s ‘Auto’ mode and explore the capabilities of your digital camera. There is, however, a lot of power and flexibility hidden just behind these letters P Av Tv M (or P A S M depending on your brand of camera) once you learn a little and experiment with them. I had previously only dabbled with these modes on my first two digital cameras (P&S) for the first 6 years of my digital photography. Since I got my first DSLR, I’ve jumped in head-first trying to learn the finer points of my camera’s capabilities and why (and when) I might use these various modes. Experimenting with these modes and observing the results will both improve your understanding of photography and hopefully open doors into what you can capture creatively with your camera.
Full Auto - Just like it sounds: the camera will choose your shutter speed, aperture, focal points, ISO, metering mode, white balance and whether or not to use the flash without any input from you. This will result in a "correct" exposure and a decent picture most times. The modern camera is a machine with numerous sensors and intelligent brains, but it is basically responding to measurements from its sensors, not “comprehending” what it is taking a picture of or what your intended picture should look like (though more and more point-and-shoot cameras are including face recognition and even smile recognition.) It may deploy the flash when you would use a longer exposure and natural light, or it may over- or underexpose the image because of how it metered the scene instead of what you “meant” for the camera to capture. These unintended results can be controlled more accurately and creatively by learning how to control you camera in the different modes below.
P (Program AE (or Flexible Program) Mode) - I find it easiest to think of this as a semi-automatic mode that will allow you to make certain general adjustments to shutter speed and aperture. The camera calculates the shutter speed and aperture for “correct” exposure and allows you to choose from several different shutter speed/aperture combinations (with the main dial just behind your shutter release switch) that will all form a “correct” exposure. ISO, AF Mode, White Balance, Metering Mode, and Flash are all completely manual in this mode. This is a good mode to start exploring, it’s like the camera is guiding you, but still letting you make decisions to affect the outcome of the picture you are taking (you can choose a different exposure time or different aperture for a particular effect, for instance.)
A or Av (Aperture Priority AE Mode) - The camera will allow you to select an aperture (with the main dial) and it will automatically adjust the shutter speed to make a correct exposure. A wider aperture (that is a smaller f/number) will have a narrow depth-of field and a smaller aperture (a larger f/number) will have a larger depth-of-field. This allows you to control the range of objects in your photo that are in sharp focus and control the blur of the background in your photographs. Keep in mind the effect of the shutter speeds the camera is selecting in terms of freezing or blurring motion and minimizing camera shake. ISO, AF Mode, White Balance, Metering Mode, and Flash are all completely manual in this mode. As an exercise, try shooting a moderately close shot of a flower, a letter, or the back of a playing card. Shoot with a wide open aperture, a medium aperture, and a stopped down aperture. Notice the difference in effect on your resulting photograph. Here are some examples illustrating the concept of depth-of-field from my photography.
S or Tv (Shutter Priority AE Mode) - The camera will allow you to select a shutter speed (with the main dial) and will adjust the aperture automatically to make a correct exposure. Basically you’ll control the time the shutter is open and the camera will adjust the aperture setting to make a correct exposure. A faster shutter speed tends to freeze motion and reduces shake. A slower shutter speed allows photography in lower light settings, blurs motion, and may unintentionally reveal shaking of the camera operator. ISO, AF Mode, White Balance, Metering Mode, and Flash are all completely manual in this mode. Here are some examples of longer exposures from my photography.
M (Manual Exposure Mode) - ISO, AF Mode, White Balance, Metering Mode, and Flash are all completely manual in this mode. The exposure scale which usually shows your exposure compensation, acts as an exposure meter in real time. You must choose both the shutter speed and the aperture you want to take the picture with every time. If you don’t change the setting, it will use the setting from the previous picture or the previous session. Experiment with manual mode my noting what the camera is guiding you to use (especially the shutter speed and aperture settings) in Program (P), Aperture Priority (A), and Shutter Priority (S) modes and use them as a starting point. Manual mode can be very useful when shooting multi-part panoramas as it allows you to keep the exposure consistent as you pan through your shots, making the images easier to stitch together accurately and smoothly. This mode puts all the exposure/aperture decisions in your hands. The camera will indicate whether or not the exposure is correct, but won’t do anything to correct it, that’s your job (or you may be over-/under-exposing for a particular reason or to get a specific effect (silhouettes, for instance.)
Specialty Modes - Almost all cameras have a range of preset modes for Sports, Fireworks, Portrait, Landscape, Indoor, Snow, Beach, etc. Please read your owner’s manual for which modes your camera supports and how to use them. There are a large number of options on the average digital camera today, just remember that you’ll only be adjusting a handful of them at a time typically. Don’t get overwhelmed with all the choices. Take some time in a controlled environment with no time constraints to experiment with your camera. Play with shutter speeds and understand how they can freeze or blur motion. Take a series of the same shot with different apertures and notice how the depth of field changes. Experiment with Autofocus (AF) Modes and Metering Modes. Consider how and where you’d want to use the techniques you’ll discover. When it all clicks and you can understand and control this machine in your hands, it’s so much more than just hitting the shutter release and “hoping” for a good result. Please stop by and see more of my photography.