Читать книгу Canon EOS Rebel T8i/850D For Dummies - King Julie Adair, Julie Adair King - Страница 30

If you’re never used a dSLR before, you may be unfamiliar with how to operate the lens. The following basics are specific to the 18–55mm kit lens sold with the T8i/850D, but they apply to many other lenses that support autofocusing with the camera. (You should explore the lens manual for specifics, of course.)

 Focusing: Set the lens to automatic or manual focusing by moving the AF/MF switch, labeled in Figure 1-32. Move the switch to the AF position for autofocusing and to MF for manual focusing. Then proceed as follows:Autofocusing: Press and hold the shutter button halfway or press the AF ON button. In Live View mode, you also have the option of tapping the touchscreen to focus. (You must enable this feature; Chapter 5 has details.)Manual focusing: After setting the AF/MF switch to MF, rotate the focusing ring on the lens until your subject appears sharp in the viewfinder or on the Live View screen. The position of the focusing ring varies depending on the lens; again, Figure 1-32 shows the ring as it appears on the 18–55mm kit lens. To save battery power, the focus motor in STM (stepping motor) lenses, such as the 18–55mm kit lens, automatically goes to sleep after a period of inactivity. While the lens is napping, manual focusing isn’t possible (the focusing ring is free to turn, but the lens does not focus). The same is true if the camera itself goes into sleep mode, which is determined by the Auto Power Off feature on Setup Menu 2. Either way, wake up the camera and lens by pressing the shutter button halfway.See Chapter 5 for more help with both automatic and manual focusing.

 Zooming: If you bought a zoom lens, it has a movable zoom ring. The location of the zoom ring on the kit lens is shown in Figure 1-32. To zoom in or out, rotate the ring. Zooming changes the lens focal length. (If you’re new to that term, the sidebar “Focal length and the crop factor,” later in this chapter, explains the subject.) On the kit lens, you can determine the focal length of the lens by looking at the number aligned with the bar that I labeled focal-length indicator in Figure 1-32.

 Enabling image stabilization: Many Canon lenses, including the kit lens, offer this feature, which compensates for small amounts of camera shake that can occur when you handhold the camera. Camera movement during the exposure can produce blurry images, so turning on image stabilization can help you get sharper handheld shots.FIGURE 1-32: Here are a few features that may be found on your lens. However, when you use a tripod, image stabilization can have detrimental effects because the system may try to adjust for movement that isn’t actually occurring. Although this problem shouldn’t be an issue with most Canon IS lenses, if you do see blurry images while using a tripod, try turning the feature off. (You also save battery power by turning off image stabilization.) If you use a monopod, leave image stabilization turned on so it can help compensate for any accidental movement of the monopod.On non-Canon lenses, image stabilization may go by another name: anti-shake, vibration compensation, and so on. In some cases, the manufacturers recommend that you leave the system turned on or select a special setting when you use a tripod, so check the lens manual for information.Whatever lens you use, image stabilization isn’t meant to eliminate the blur that can occur when your subject moves during the exposure. That problem is related to shutter speed, a topic you can explore in Chapter 4.

 Removing a lens: After turning the camera off, press and hold the lens-release button on the camera (refer to Figure 1-32), and turn the lens toward the shutter button side of the camera until the lens detaches from the lens mount. Put the rear protective cap onto the back of the lens and, if you aren’t putting another lens on the camera, cover the lens mount with its cap, too. Always switch lenses in a clean environment to reduce the risk of getting dust, dirt, and other contaminants inside the camera or lens. Changing lenses on a sandy beach, for example, isn’t a good idea. For added safety, point the camera body slightly down when performing this maneuver; doing so helps prevent any flotsam in the air from being drawn into the camera by gravity.

 Decoding Canon lens terminology: When you shop for Canon lenses, you encounter these lens specifications:EF and EF-S: EF stands for electro focus; the S stands for short back focus. And that simply means the rear element of the lens is closer to the sensor than with an EF lens. The good news is that your T8i/850D works with both of these Canon lens types.IS: Indicates that the lens offers image stabilization.STM: Refers to stepping motor technology, an autofocusing system that is designed to provide smoother, quieter autofocusing.The 18–55mm kit lens is an EF-S lens with both image stabilization and stepping motor technology. You can find complete lens info on the ring surrounding the front element of the lens.