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S: Shutter Priority Mode


S mode is what we photographers commonly refer to as Shutter Priority mode. The nomenclature can vary between cameras—some manufacturers use the initial T (for Time) to indicate you are shooting in Shutter Priority mode. Luckily, the A7/A7R makes it easy on us. S stands for shutter; hence, Shutter Priority. It can’t be any more practical than that, right?

Like Program Auto mode, S mode gives us more freedom to control certain aspects of our photography. In this case, we are talking about shutter speed. The selected shutter speed determines just how long you expose your camera’s sensor to light. The longer it remains open, the more time your sensor has to gather light. The shutter speed also, to a large degree, determines how sharp your photographs are. This is different from the image being sharply in focus. Two of the major influences on the sharpness of an image are camera shake and the subject’s movement. Because a slower shutter speed means that light from your subject is hitting the sensor for a longer period of time, any movement by you or your subject will show up in your photos as blur.

When to use Shutter Priority (S) mode

  • When working with fast-moving subjects where you want to freeze the action (Figure 4.2); much more on this in Chapter 6

    Figure 4.2

    Figure 4.2 Fast-moving subjects in proximity to the camera can be frozen with the right shutter speed.

    ISO 200 • 1/1250 sec. • f/5.6 • 70–400mm lens at 400mm

  • When you want to emphasize movement in your subject with panning or with motion blur (Figure 4.3)

    Figure 4.3

    Figure 4.3 Slowing down the shutter speed allows your photographs to convey a sense of movement, indicated by the lateral blurring of the background in this pan.

    ISO 100 • 1/100 sec. • f/8 • 16–35mm lens at 16mm

  • When you want to use a long exposure to gather light over a long period of time (Figure 4.4); more on this in Chapter 8

    Figure 4.4

    Figure 4.4 Dusk is the perfect time to balance house lights with the color of the sky. Lock the camera down on a steady tripod to keep everything sharp.

    ISO 100 • 15 sec. • f/8 • 55mm lens

  • When you want to create smooth, flowing patterns in moving objects (Figure 4.5)

    Figure 4.5

    Figure 4.5 A long exposure creates a flowing pattern out of car taillights.

    ISO 100 • 2 sec. • f/9 • 24–70mm lens at 24mm

As you can see, the subject of your photo usually determines whether or not you will use S mode. It is important that you be able to visualize the result of using a particular shutter speed. The great thing about shooting with digital cameras is that you get instant feedback by checking your shot on the LCD screen. But what if your subject won’t give you a do-over? Such is often the case when shooting sporting events. It’s not like you can ask the quarterback to throw that touchdown pass again because your last shot was blurry from a slow shutter speed. This is why it’s important to know what those speeds represent in terms of their ability to stop the action and deliver a blur-free shot.

First, let’s examine just how much control you have over the shutter speeds. The A7/A7R has a shutter speed range from 1/8000 of a second all the way down to 30 seconds. With that much latitude, you should have enough control to capture almost any subject. The other thing to think about is that S mode is considered a “semiautomatic” mode. This means that you are taking control over one aspect of the total exposure while the camera handles the other. In this instance, you are controlling the shutter speed and the camera is controlling the aperture. This is important to know because there will be times that you want to use a particular shutter speed but your lens won’t be able to accommodate your request.

For example, you might encounter this problem when shooting in low-light situations: If you are shooting a fast-moving subject that will blur at a shutter speed slower than 1/125 of a second but your lens’s largest aperture is f/3.5, you might see your aperture display in the electronic viewfinder and the rear LCD panel begin to blink. This is your warning that there won’t be enough light available for the shot—due to the limitations of the lens—so your picture will be underexposed (too dark).

Another case where you might run into this situation is when you are shooting moving water. To get that look of silky, flowing water, it’s usually necessary to use a shutter speed of at least 1/15 of a second, if not longer. If your waterfall is in full sunlight, you may get that blinking aperture display once again because the lens you are using only closes down to f/22 at its smallest opening. In this instance, your camera is warning you that you will be overexposing your image (too light). There are workarounds for these problems, which we will discuss later (see Chapter 7), but it is important to know that there can be limitations when using S mode.

Setting up and shooting in S mode

  1. Turn your camera on, and then turn the Mode dial to align the S with the indicator line.
  2. To select your ISO, press the right side of the Control wheel (next to where it reads ISO), rotate the Control wheel to the desired setting, and press the middle of the wheel to select (the ISO selection will appear in the electronic viewfinder and the rear LCD panel).
  3. Point the camera at your subject, and then activate the camera meter by depressing the shutter button halfway.
  4. View the exposure information in the electronic viewfinder or on the rear LCD panel.
  5. While the meter is activated, use your thumb to roll the Control dial left and right to see the changed exposure values. Roll the dial to the right for faster shutter speeds and to the left for slower speeds.
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