Canon EOS Rebel T8i/850D For Dummies. Julie Adair KingЧитать онлайн книгу.
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.
FOCAL LENGTH AND THE CROP FACTOR
The angle of view that a lens can capture is determined by its focal length, or in the case of a zoom lens, the range of focal lengths it offers. Focal length is measured in millimeters. The shorter the focal length, the wider the angle of view. As focal length increases, the angle of view narrows, and the subject occupies more of the frame.
Generally speaking, lenses with focal lengths shorter than 35mm are considered wide angle lenses and lenses with focal lengths greater than 80mm are considered telephoto lenses. Anything in the middle is a “normal” lens, suitable for shooting scenes that don’t require either a wide or narrow angle of view.
Note, however, that the focal lengths stated in this book and elsewhere are 35mm-equivalent focal lengths. Here’s the deal: When you put a standard lens on most dSLR cameras, including the T8i/850D, the available frame area is reduced, as if you took a picture on a camera that uses 35mm film negatives and cropped it. This crop factor varies depending on the camera, which is why the photo industry adopted the 35mm-equivalent measuring stick as a standard. With the T8i/850D, the crop factor is roughly 1.6x. In the figure here, the red frame indicates the portion of a 35mm frame that is captured at that crop factor.
When shopping for a lens, it’s important to remember this crop factor to make sure you get the focal length designed for the type of pictures you want to take. Just multiply the lens focal length by 1.6 to determine the actual angle of view.
Working with Memory Cards
As the medium that stores your picture files, the memory card is a critical component of your camera. See the steps at the start of this chapter for help installing a card; follow these tips for buying and maintaining cards:
Buying SD cards: SD (Secure Digital) cards carry slightly different names depending on their storage capacity: SD cards offer less than 4GB of storage space; SDHC cards can hold 4GB–32GB of data; and SDXC cards can store more than 32GB.Aside from card capacity, the other specification to note is card speed, which indicates how quickly data can be moved to and from the card. Card speed is indicated in several ways. The most common spec is SD Speed Class, which rates cards with a number between 2 and 10, with 10 being the fastest. Most cards also carry another designation, UHS-1, -2, or -3; UHS (Ultra High Speed) refers to a new technology designed to boost data transmission speeds above the normal Speed Class 10 rate. The number 1, 2, or 3 inside a little U symbol tells you the UHS rating. Your camera can use UHS-2 and -3 cards, but you won’t get any extra speed benefit; the speed advantage with the T8i/850D tops out at UHS-1.Some SD cards also are rated in terms of how they perform when used to record video — specifically, how many frames per second the card can handle. As with the other ratings, a higher video-speed number indicates a faster card.
Formatting a card: The first time you use a new memory card, format it by choosing the Format Card option on Setup Menu 1. This step ensures the card is properly prepared to record your pictures. See the upcoming section “Setup Menu 1” for more information.
Removing a card: First, check the status of the memory-card access lamp, found just above the card door on the back-right side of the camera. After making sure that the lamp is off, indicating that the camera has finished recording your most recent photo, turn off the camera. Open the memory card door, depress the memory card slightly and then lift your finger. The card should pop halfway out of the slot, enabling you to grab it by the tail and remove it.
Handling cards: Don’t touch the gold contacts on the back of the card. (See the right card in Figure 1-33.) When cards aren’t in use, store them in the protective cases they came in or in a memory card wallet. Keep cards away from extreme heat and cold as well.
Locking cards: The tiny switch on the side of the card, labeled “Lock switch” in Figure 1-33, enables you to lock your card, which prevents any data from being erased or recorded to the card. If you insert a locked card into the camera, a message on the monitor alerts you to that fact. You can safeguard individual images from accidental erasure by using the Protect Images option on Playback Menu 1; Chapter 10 tells you how. Note, though, that formatting the card does erase even protected pictures; the safety feature prevents erasure only when you use the camera’s Erase function, also covered in Chapter 10.
FIGURE 1-33: Avoid touching the gold contacts on the card.
Reviewing Basic Setup Options
Your camera offers scads of options for customizing its performance. Later chapters explain settings related to picture-taking, such as those that affect flash behavior and autofocusing. The rest of this chapter offers a quick rundown of options on the Setup menu, which are mainly (but not all) related to general camera operations. Some of these features deserve only a brief glance; others may require your attention on a regular basis. I’ve also included advice on a few additional pre-use options you may want to consider that aren’t found on the Setup menu.
