Tv mode gives you full control over the shutter speed—you pick the shutter speed and the camera determines the aperture. In many instances of sports and action photography, you will be working with very fast shutter speeds, and using the Tv mode will give you the control you need to capture high-speed images (Figure 6.4).
In order to use a fast shutter speed, you need to be in an environment with suffi cient light available for the speed you want to use. You might decide to set your aperture at a wide f-stop in order to bring more light into the sensor to balance the fast shutter speed. However, there may be times when your environment is just too dark for what you want to shoot—you’ll know this because the aperture value will fl ash on the top LCD Panel and also on the viewfi nder info screen. When the light is insuffi cient for the shutter speed and aperture combination you want to use, you’ll need to change your ISO settings.
What’s great about digital cameras is that they allow the user to change the ISO as often as needed. With fi lm, each individual roll of fi lm had a specifi c ISO number and couldn’t be changed from frame to frame, as can be done with digital cameras today. It can be diffi cult for new photographers to decide what ISO to use at fi rst, but once you understand how the process works, it’s much easier to make that decision.
When I’m on a photo shoot, I like to keep my ISO very low and usually shoot at its lowest setting (ISO 100). I do this because at low ISO numbers, the digital noise is insignifi cant and hardly visible. When you start cranking that number up, the camera’s sensor becomes more sensitive to light and you can increase your shutter speeds; however, the noise level will be much greater. For my line of work, I tend to keep my images as noise-free as possible, but in a photo where the subject and activity being photographed are more important than the technical quality of the pixels, having the ability to change the ISO is a big advantage. It’s a good option to have when you’re in an environment that you can’t control, and depending on the fi nal output (web, print, and so on), it may or may not make much difference in the overall quality of the image. With the 7D you can quickly adjust the ISO number as needed with just a few simple steps.
ADJUSTING YOUR ISO ON THE FLY
- Check for the blinking aperture readout in the bottom portion of your viewfi nder (A).
- A blinking aperture is an indication that your image will be underexposed. In this case the aperture is at its lowest setting, so your only option is to increase the ISO. To do so move your index fi nger back from the Shutter button and press the ISO button (B).
- Now move your fi nger forward to the Main dial and raise the ISO to the next highest level by rotating it right.
- Lightly press the Shutter button and check to see if the aperture is still blinking.
- If it’s not blinking, shoot away. If it is, repeat steps 2–4 until it is set correctly.
When photographing sports and action images, try to find new and creative ways to capture your subject. In this image (Figure 6.5), I knew that I would need a fast shutter speed to catch the basketball player mid-air, so I positioned myself facing the sun and silhouetted him as he was jumping up to take a shot. The bright light from the sun not only allowed me to use a fast enough shutter speed to catch the action but also added a unique quality to the scene.