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.
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 90D, 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 90D, 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 that 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.
Removing a lens
After turning the camera off, press and hold the lens-release button on the camera (refer to Figure 1-25), 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.
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 90D 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’s designed to provide smoother, quieter autofocusing.
USM: Refers to the ultrasonic motor. USM is an older technology than STM, but USM lenses still offers quick, professional-quality autofocusing.
The 18–55mm kit lens is an EF-S lens with both Image Stabilization and stepping motor technology. The 18–135mm kit lens is also an EF-S lens with Image Stabilization technology. Complete lens info can also be found on the ring surrounding the front element of the lens.
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 the tips in this section for buying and maintaining cards.
Buying SD cards
Again, you can use regular SD cards, which offer less than 4GB of storage space; SDHC cards (4GB–32GB); and SDXC cards (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-I, -II, or -III; 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.
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 that the card is properly prepared to record your pictures. See the upcoming section “Setup Menu 1” for more information about card formatting.
Removing a card
First, check the status of the memory card access light, found just above the card door on the right side of the camera. After making sure that the light is off, indicating that the camera has finished recording your most recent photo, turn off the camera. Open the memory card door by gently pressing inwards on it and sliding it to the rear of the camera, depress the memory card slightly, and then lift your finger. The card should pop up a bit, enabling you to grab and remove it.
Handling cards
Don’t touch the gold contacts on the back of the card (see the right card in Figure 1-26). 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 1-26, enables you to lock your card, which