Using Shutter Priority (Tv) Mode to Stop Motion

In Chapter 3, we covered the shooting modes on the 6D. Tv, or Shutter Priority, mode gives you full control over the shutter speed but chooses the aperture for you. It’s commonly used in sports and action photography because it gives you the ability to adjust your shutter speed on the fly (Figure 4.4).

Figure 4.4. I used a fast shutter speed to capture this bald eagle on a tree branch in Alaska.

One of the biggest challenges of shooting images at fast shutter speeds is having enough light available. Remember that your shutter speed controls the duration that light is allowed to hit your sensor. With a fast shutter speed, you might need to use a wide-open aperture in order to counter the short time the shutter is open. There will, however, be times when it is just too dark to take an image when using Tv mode. This will be obvious because you will not be able to take the photo, and the aperture you have chosen will flash in the viewfinder and on the top LCD. In order to take one of these images, you will need to increase your ISO setting.

One of the best things about shooting with a DSLR is being able to easily change the ISO as often as you like. In the days of film cameras, every roll of film had a certain ISO speed. So if you bought ISO 400 film, that is the ISO you had to use for the duration of that roll. While it might be difficult to imagine being a Sports Illustrated photographer shooting the Super Bowl, imagine doing it 20 years ago with a film camera!

When I am out on a photo shoot, I generally try to keep my ISO as low as possible (ISO 100 in most instances). The reason for this is that as your sensor becomes more sensitive to light (higher ISO), it begins to degrade the quality of the color and add digital noise (pixelation) to your images. I recommend raising your ISO only as a last resort. This will ensure that you are always capturing the best color and lowest-possible noise—unless you have no other choice or you feel that digital noise will add to the atmosphere of the shot (a common practice for some black and white photographers). With the 6D, you can quickly adjust the ISO in just a few simple steps.

Adjusting Your ISO on the Fly

1. If the shutter speed is too fast for your aperture setting in Tv mode, you will see the aperture number blinking in your viewfinder or on the rear or top LCD panel (A). This is an indicator that your image will be underexposed and that the aperture on your lens cannot open any wider.

2. To change the ISO while looking through the viewfinder, use your index finger to press the ISO button on the top of your camera (B). (To help direct your finger, there is a bump in the middle of the button.)

3. Now move your finger back to the Main dial and move it to the right or left to increase or decrease your ISO, respectively.

4. Gently press the shutter button halfway to engage the light meter, and see if the aperture readout is still blinking.

5. If it’s not blinking, shoot away. If it is, repeat steps 2–4 until it is set correctly.

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Macro Photography and Shutter Speed

Most people do not realize that shutter speed plays such a vital role in macro photography. In the image in Figure 4.5, I knew that I wanted to get close to my subject to capture as much detail as possible. The challenge with macro photography is that even the smallest movement by your subject can result in an out-of-focus image. When I realized there was a soft breeze blowing this sunflower back and forth, I adjusted my shutter speed so that it was fast enough to freeze the movement in the scene.

Figure 4.5. By increasing my shutter speed, I was able get an in-focus shot even while the flower was moving back and forth in the wind.

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