HBEff You can adjust aperture and shutter speed only in P, Tv, Av, and M exposure modes. In A-DEP mode, the camera forces you to use its selected exposure settings. (You can, however, tweak the exposure by using the exposure-compensation feature discussed in the next section.)
To see the current exposure settings, start by pressing the shutter button halfway. The following activities then take place:
✓ The exposure meter comes to life. If autofocus is enabled, focus is also set at this point.
✓ The current aperture and shutter speed appear in the viewfinder and Shooting Settings display. In Live View mode, the settings appear under the image preview on the monitor.
✓ In manual exposure mode, the exposure meter also lets you know whether the current settings will expose the image properly. In the other advanced exposure modes — Tv, Av, P, and A-DEP — the camera indicates an exposure problem not with the meter, but by flashing either the shutter speed or f-stop value. (See the section "Monitoring Exposure Settings," earlier in this chapter, for details.)
Noise, the digital defect that gives your pictures a speckled look (refer to Figure 5-7), can occur for two reasons: a high ISO speed and a long exposure time.
The Rebel XS/1000D offers two noise-removal filters, one designed to help eradicate ISO-related noise and another to dampen the type of noise that occurs during long exposures. Both filters are provided through Custom Functions, however, which means that you can access them only in the advanced exposure modes.
To enable High ISO noise reduction, visit Setup Menu 3, select Custom Functions, press Set, and then use the right or left cross key to select Custom Function 4, as shown in the left figure here. (The Custom Function number appears in the upper-right corner of the screen.) Press Set to activate the options, highlight On, and press Set again.
For long-exposure noise reduction, select Custom Function 3 and press Set. You then can choose from these settings, shown in the right figure below. The options work as follows:
✓ Off: No noise reduction is applied. This is the default setting.
✓ Auto: Noise reduction is applied when you use a shutter speed of 1 second or longer, but only if the camera detects the type of noise that's caused by long exposures.
✓ On: Noise reduction is always applied at exposures of 1 second or longer.
Before you enable noise reduction, be aware that doing so has a few disadvantages. First, the filter is applied after you take the picture, as the camera processes the image data and records it to your memory card. The time needed to apply the filter is about the same as the original exposure time, which slows down your shooting speed.
Second, noise-reduction filters work primarily by applying a slight blur to the image. Don't expect this process to totally eliminate noise, and do expect some resulting image softness. You may be able to get better results by using the blur tools or noise-removal filters found in many photo editors because then you can blur just the parts of the image where noise is most noticeable — usually in areas of flat color or little detail, such as skies.
Finally, if you enable ISO noise reduction, you lose the option of continuous shooting (enabled through the Drive mode setting, covered in Chapter 2) and White Balance Bracketing (an advanced color feature you can explore in Chapter 6).
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Compared to film cameras, digital cameras are easy to use, fun and extremely versatile. Every day there’s more features being designed. Whether you have the cheapest model or a high end model, digital cameras can do an endless number of things. Let’s look at how to get the most out of your digital camera.