Canon PowerShot G12, Av: Aperture Priority Mode

You wouldn’t know it from its name, but Av mode is one of the most useful and popular of the Creative modes. Av stands for Aperture Value and, like Time Value, it’s another term that you’ll never hear a photographer toss around. The mode, however, is one of my personal favorites, and I believe that it will quickly become one of yours as well. Av, more commonly referred to as Aperture Priority mode, is also deemed a semi- automatic mode because it allows you to once again control one factor of exposure while the camera adjusts for the other.

Why is this one of my favorite modes? It’s because the aperture of your lens dictates depth of field. Controlling depth of field lets you direct attention to what’s important in your image by specifying how much area in your image is sharp. If you want to isolate a subject from the background, such as when shooting a portrait, a large aperture keeps the focus (literally) on your subject and makes both the foreground and background blurry. If you want to keep the entire scene sharply focused, such as with a landscape scene, then using a small aperture will render the greatest amount of depth of field possible.

When to use Aperture Priority (Av) mode

  • When shooting macro, or close-up, photography (Figure 4.6)
  • When shooting portraits or wildlife (Figure 4.7)
  • When shooting architectural photography, which often benefits from a large depth of field (Figure 4.8)
  • When shooting most landscape photography

Aperture priority helps keep the foreground image in focus in macro photos. [Photo: Lynette Coates]
Figure 4.6 Aperture priority helps keep the foreground image in focus in macro photos. [Photo: Lynette Coates]
A large aperture created a blurry background so all the emphasis was left on the subject. [Photo: Anneliese Voigt]
Figure 4.7 A large aperture created a blurry background so all the emphasis was left on the subject. [Photo: Anneliese Voigt]
Using the camera’s smallest available aperture provides a large depth of field. [Photo: Jeff Carlson]
Figure 4.8 Using the camera’s smallest available aperture provides a large depth of field. [Photo: Jeff Carlson]
F-stops and aperture

As discussed earlier, when referring to the aperture value, you will find it described as an f-stop. The f-stop is one of those old photography terms that, technically, relates to the focal length of the lens (e.g., 200mm) divided by the effective aperture diameter. These measurements are defined as “stops” and work incrementally with your shutter speed to determine proper exposure. Older camera lenses used one-stop increments to assist in exposure adjustments, such as 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, and 22. Each stop represents about half the amount of light entering the lens iris as the larger stop before it. Today, all adjustments to this setting are performed via the camera’s electronics. The stops are also now typically divided into 1/3-stop increments to allow much finer adjustments to exposures.

So we have established that Aperture Priority (Av) mode is highly useful in controlling the depth of field in your image. But it’s also pivotal in determining the limits of available light that you can shoot in. The larger the maximum aperture, the less light you need in order to achieve an acceptably sharp image. You will recall that, when in Tv mode, there is a limit at which you can handhold your camera without introducing movement or hand shake, which causes blurriness in the final picture. A larger aperture lets in more light at once, which means that you can use a faster shutter speed. On the other hand, bright scenes require the use of a small aperture (such as f/8), especially if you want to use a slower shutter speed. That small opening reduces the amount of incoming light, and this reduction of light requires that the shutter stay
open longer.

Setting up and shooting in Av mode

  1. Turn your camera on and turn the Mode dial to Av.
  2. Select your ISO by rotating the ISO dial.
  3. Rotate the Front dial to choose an aperture setting, which appears at the bottom of the LCD. Roll the dial to the right for a smaller aperture (higher f-stop number) and to the left for a larger aperture (smaller f-stop number).
  4. Point the camera at your subject and then activate the camera meter by pressing the shutter button halfway to preview the exposure. As with the Shutter Priority mode, the orange light by the viewfinder will blink if the image is underexposed or overexposed.
  5. Release the button and adjust the Front dial to change the setting.
  6. Press the shutter button fully when you’re ready to shoot.

Canon PowerShot G12 Scene Modes

One problem with Auto mode is that it has no idea what type of subject you are photographing and therefore attempts to make a best-guess
reading of each situation. Many Scene modes are optimized for many of the shooting scenarios you’re likely to encounter, and some apply in-camera effects that would be difficult or time-consuming to replicate on a computer later.

Even if you’re planning to shoot most often using the camera’s advanced modes, the Scene modes can be a helpful training tool. Shoot a few shots using the Sports preset, for example, and note the shutter speed, aperture, and ISO settings that the camera chose. Then, fine-tune your own settings using the Scene values as a baseline.

Using the Scene Modes

  1. Set the Mode dial to the SCN setting.
  2. Press the Function/Set button. The Scene modes are selected at the top of the menu.
  3. Rotate the Control dial until your chosen scene icon appears.
  4. Press the Function/Set button to choose the scene.

Portrait

Shooting portraits is a perfect example of a common scene (Figure 3.2). This mode emphasizes skin tones and makes them a little softer to improve the skin’s look, avoiding the harsh, greenish cast that can occur under some types of lighting.

Portrait mode is a great choice for shots like this one. Positioning the subject to the side of the frame makes the shot stand out among portrait photos. [Photo: jvlphoto.com]
Figure 3.2 Portrait mode is a great choice for shots like this one. Positioning the subject to the side of the frame makes the shot stand out among portrait photos. [Photo: jvlphoto.com
Landscape

As you might have guessed, the Landscape scene has been optimized for shooting landscape images. The camera does its best to boost the greens and blues in the image (Figure 3.3). This makes sense, since the typical landscape would be outdoors where grass, trees, and skies should look more colorful. This mode also increases the sharpness that is applied during processing and utilizes the lowest ISO settings possible in order to keep digital noise to a minimum.

This type of scene just calls out for the Landscape mode. The vegetation and sky were given more saturation, and a medium aperture was used for greater depth of field. [Photo: Deak Wooten]
Figure 3.3 This type of scene just calls out for the Landscape mode. The vegetation and sky were given more saturation, and a medium aperture was used for greater depth of field. [Photo: Deak Wooten
Kids & Pets

It’s hard to get any more specific than this. Kids and pets have a habit of not always posing for the shot you want…or the shot you think you might get…if only they’d…just…stop…moving…for a moment. The Kids & Pets mode uses a fast shutter speed, wide aperture, and high ISO to freeze the action of these moving targets.

Sports

While this is called the Sports scene, you can use it for any moving subject that you are photographing. The mode is built on the principles of sports photography: continuous focusing and fast shutter speeds (Figure 3.4). To handle these requirements, the camera sets the drive mode to Continuous AF shooting and the ISO to Auto. Overall, these are sound settings that will capture most moving subjects well.

You can, however, run the risk of too much digital noise in your picture if the camera decides you need a very high ISO (such as 1600). Also, when using the Sports scene, you will need to frame your subject in the middle of the viewfinder so the center focus point is on them.

This is the type of shot that was made for Sports mode, where action-freezing shutter speeds and continuous focusing capture the moment. [Photo: Rick Lewis]
Figure 3.4 This is the type of shot that was made for Sports mode, where action-freezing shutter speeds and continuous focusing capture the moment. [Photo: Rick Lewis
Smart Shutter

Most of the Scene modes are easy to figure out from their names, but what’s so smart about Smart Shutter? It’s designed for getting good shots of people, especially when you’re shooting pictures of yourself in a group of people. Smart Shutter has three modes, accessible by pressing the Display button:

  • Smile: When you look at the camera and smile, a shot is taken—you don’t need to press the shutter release button at all.
  • Wink Self-Timer: As you frame your subjects, the G12 detects one person’s face. Press the shutter release button. The camera waits for that person to wink, then counts down a couple of seconds before taking the shot. (If it doesn’t detect a wink, the shot fires after 15 seconds.) You may need to wink with both eyes to trigger the shutter.
  • Face Self-Timer: Press the shutter release button and then look directly into the camera to start the self-timer countdown.

For each mode, you can set the camera to shoot up to 10 successive shots by pressing the up or down button.

Super Vivid, Poster Efect, Nostalg ic, and Fish-Eye

These four Scene modes replicate looks that you can achieve using post-processing software such as Adobe Photoshop Elements, iPhoto,
or other programs. The advantage to using them while shooting is that you don’t need to spend time applying the effects later. The disadvantage is that you’re stuck with the effect for the shot. Personally, I’d prefer to do the processing later in software using a “normal” shot where I have more control.

Color Accent & Color Swap

The Color Accent mode picks out one color in your scene and renders everything else black and white. Press the Display button and position the focus box on the color you want to preserve, and then press the left button to lock it in.

Color Swap works in a similar fashion, only in addition to setting a target color, you then point at a different color in your scene and press the Right button to set the replacement hue. Anything blue, for example, could appear red.

Again, however, I’d much rather do these adjustments in software later.

HDR

HDR, or High Dynamic Range, is a method of combining several shots at different exposures to bring out more detail than you could normally get with just one shot. For example, you could use HDR to shoot a scene where a person in the foreground might otherwise be put into silhouette by a bright sky in the background. HDR used to be possible only in software, but now the HDR Scene mode does the work in-camera.

For best results, mount the G12 on a tripod or other stationary surface, then press the shutter release button. The camera takes three shots and then combines them into one HDR image. It’s best to turn off the image stabilizer (IS) when using this mode; that sounds counterintuitive, but the camera could overcompensate and produce a blurry shot.

Miniature Efect

The Miniature Effect mode pulls off a neat trick: By selectively blurring areas of an image, the effect makes objects in the center look like miniature toys (Figure 3.5). Another term for this effect is tilt-shift, which is accomplished on DSLRs using expensive lenses with selective focus controls.

With the mode enabled, press the Display button to adjust how the focus is centered. Press Set to change the highlight rectangle from horizontal to vertical (or vice versa). Then, use the zoom control to make the area larger or smaller.

The Miniature Effect mode uses a tilt-shift effect to concentrate focus on one area, which makes otherwise normal scenes appear as if they’re miniatures. [Photo: Jeff Carlson]
Figure 3.5 The Miniature Effect mode uses a tilt-shift effect to concentrate focus on one area, which makes otherwise normal scenes appear as if they’re miniatures. [Photo: Jeff Carlson
 Beach and Snow

Shooting at the beach or in the snow, while representing opposite extremes of temperature, share a trait that’s problematic to digital cameras: The environments are often very bright from light reflecting off sand or snow, which can confuse a camera’s light meter. These modes compensate for the brightness.

Underwater

Fishy environments feature the opposite trait of the Beach and Snow modes. Often underlit and exhibiting blue-green color casts, underwater and aquarium shots can easily turn muddy. The Underwater mode reduces the blue-green coloring and enhance the other colors. (And for today’s obvious public service announcement, Canon wants you to know that it’s highly recommended that you put your G12 in a waterproof enclosure before submerging it.)

Foliage

I never paid as much attention to trees and flowers as I do now that I carry a camera everywhere. The Foliage scene boosts colors to make them more vivid, a welcome enhancement in the autumn or spring especially (Figure 3.6).

The Foliage scene brings out the color in flowers, leaves, and other natural subjects. [Photo: Jeff Carlson]
Figure 3.6 The Foliage scene brings out the color in flowers, leaves, and other natural subjects. [Photo: Jeff Carlson
Fireworks

With only a few opportunities each year to take photos of fireworks (unless you live at a Disney theme park), it seems odd that Canon would include a scene dedicated to the nighttime explosions. However, fireworks are tricky to photograph well. The Fireworks scene features long exposures and a narrow aperture to emphasize the bright colors against a dark sky (Figure 3.7).

Fireworks can be notoriously tricky to capture. [Photo: John Wayne Lucia III]
Figure 3.7 Fireworks can be notoriously tricky to capture. [Photo: John Wayne Lucia III

Canon PowerShot G12 Auto Mode

Auto mode is all about (mostly) thought-free photography. There is little to nothing for you to do in this mode except point and shoot. Your biggest concern when using Auto mode is focusing. The camera utilizes the automatic focusing modes to achieve the best possible focus for your picture. Press the shutter button down halfway while looking at the LCD, and you will see the autofocus frame light up over the subject. Now just press the shutter button the rest of the way to take the photo. It’s just that easy (Figure 3.1). The camera takes care of all your exposure decisions, including when to use flash. (In fact, most other functions are disabled.)

The G12 offers a bit more information about how it’s going to handle a shot when using the Auto mode. An icon appears at the upper-right corner of the screen indicating the type of scene it has detected.

Let’s face it: This is the lazy person’s mode. But sometimes it’s nice to be lazy and click away without giving thought to anything but preserving a memory. There are times, though, when you will want to start using your camera’s advanced features to improve your shots.

Auto works great when you just want to snap some shots and don’t want to think too much. This picture was taken during a stroll near my office in Seattle. [Photo: Jeff Carlson]
Figure 3.1 Auto works great when you just want to snap some shots and don’t want to think too much. This picture was taken during a stroll near my office in Seattle. [Photo: Jeff Carlson

Auto Tracking Mode

The Auto mode has a feature you may have missed while skimming the user manual. When you press the Metering Light button (above and to the right of the Control dial), the G12’s Tracking mode is enabled. Move the camera so the selection rectangle is over an object you want to keep in focus and press the shutter button halfway—a blue rectangle tracks with that object, even when you move the camera or the object moves. Press the shutter button fully to take the shot.