Just be prepared to succumb to lens lust, a strange malady that strikes all owners of dSLRs sooner or later. Before you know it, you'll find yourself convinced you must have optical goodies like the lens shown in Figure 1-1, a telephoto macro lens that's absolutely essential (you'll think) for taking photos of butterflies from enough of a distance to avoid scaring the timid creatures away.

If you're ready to say sayonara to film, adios to poorly exposed and poorly composed pictures, and auf Wiedersehen to cameras with sluggardly performance, it's time to get started.

The sections that follow (as well as other chapters in this part) introduce you to the technical advantages of the digital SLR and how to use the dSLR's features to their fullest. When you're ready to expand your photographic horizons even farther, Parts II, III, and IV help you master the basics of digital photography, go beyond the basics to conquer the mysteries of photo arenas such as action, flash, and portrait photography, and then discover how you can fine-tune your images, organizing them for sharing and printing.

Improving Your Photography with a dSLR

The differences between digital SLRs and the camera you were using before you saw the light will depend on where you're coming from. If your most recent camera was a point-and-shoot digital model, you know the advantages of being able to review your photos on an LCD an instant after you took them, and you also know the benefits of fine-tuning them in an image editor. If you're switching to a digital SLR from a film SLR, you are likely a photo enthusiast already and well aware that a single lens reflex offers you extra control over framing, using focus creatively, and choosing lenses to give the best perspective. And, if you're making the huge leap from a point-and-shoot non-SLR film camera to a digital SLR, you're in for some real revelations.

A digital SLR has (almost) all the good stuff available in a lesser digital camera, with some significant advantages that enable you to take your photo endeavors to a new, more glorious level of excellence. Certainly, you can take close-ups or sports photos with any good-quality film or digital camera. Low-light photography, travel pictures, or portraits are all within the capabilities of any camera. But digital SLRs let you capture these kinds of images more quickly, more flexibly, and with more creativity at your fingertips. Best of all (at least for Photoshop slaves), a digital SLR can solve problems that previously required working long hours over a hot keyboard.

Despite the comparisons you can make to other cameras, a digital SLR isn't just a simple upgrade from a conventional film camera or another type of digital camera. A dSLR is very different from a film SLR, too, even though some vendors offer film and dSLRs that look quite a bit alike and share similar exposure metering, automatic focusing, and other electronics. If you look closely, you find that the digital SLR camera is different, and how you use it to take pictures is different.

In the sections that follow, I introduce you to the advanced features and inner workings so that you can begin getting the most out of your dSLR.

Composing shots with a more accurate viewfinder

With non-SLR cameras, what you see isn't always what you get.

Theoretically, the LCD on the back of a point-and-shoot digital camera should show exactly what you'll get in the finished picture. After all, the same sensor that actually captures the photo produces the LCD image. In practice, the LCD might be difficult to view under bright light, and it's so small (a few LCDs are only 1.5 inches diagonally) that you'll feel like you're trying to judge your image by looking at a postage stamp that's gone through the wash a few times.

The view through a non-SLR camera's optical viewfinder is likely to be even worse: tiny, inaccurate enough to make chopping off heads alarmingly easy, and with no information about what's in focus and what is not.

More advanced cameras might use an electronic viewfinder (EVF), which is a second, internal LCD that the user views through a window. EVFs provide a larger image that's formed by the actual light falling on the sensor and can be used in full sunlight without washing out. However, they might not have enough pixels to accurately portray your subject and tend to degenerate into blurred, ghosted images if the camera or subject moves during framing. They also don't work well in low light levels. An EVF is a good compromise, but not as good as a dSLR for previewing an image.

A digital SLR's viewfinder, in contrast, closely duplicates what the sensor will see, even though the image is formed optically and not generated by the sensor itself. It's all done with mirrors (and other reflective surfaces) that bounce the light from the lens to your viewfinder, sampling only a little of the light to measure exposure, color, and focus. As a result, the viewfinder image is usually bigger and brighter - from 75 percent to 95 percent (or more) of life size using a dSLR "normal" lens or zoom position, compared with 25 percent or smaller with a point-and-shoot camera's optical or LCD viewfinder. You see 95 percent of the total area captured, too.

Check out Figure 1-2 and decide which view of your subject you'd rather work with. Even the 2.5-inch LCD on the point-and-shoot model in the upperleft corner is difficult to view in bright light; the electronic viewfinder in the upper-right corner can be fuzzy, making it hard to judge focus. The digital SLR's big bright viewfinder (bottom) is, as Goldilocks would say, just right.

A dSLR shows you approximately what is in sharp focus and what is not (the depth-of-field), either in general terms (all the time) or more precisely when you press a handy button called the depth-of-field preview. Your digital SLR viewing experience is likely to be more pleasant, more accurate, and better suited for your creative endeavors.

Flexing the more powerful sensor

Digital SLR sensors are much bigger than their point-and-shoot camera counterparts, and this gives them a larger area for capturing light and, potentially, much greater sensitivity to lower light levels.

A dSLR's extra sensitivity pays off when you want to

Within the Canon digital camera line alone, you find digital SLRs with 22.2-x-14.8mm to 24-x-36mm sensors (the size of a 35mm film frame). Some of Canon's digital point-and-shoot cameras use a sensor that measures only 7.8 x 5.32mm. Put in terms that make sense to human beings, the dSLR sensors have 8 to 20 times more area than their Lilliputian sensor-mates. Figure 1-3 gives you a better idea of the relative sizes.

If you think of a sensor as a rectangular bucket and the light falling on it as a soft drizzle of rain, you see that the larger buckets are going to collect more drops (or the particles of light called photons) more quickly than the smaller ones. Because a certain minimum number of photons is required to register a picture, a larger sensor can collect the required amount more quickly, making it more sensitive than a smaller sensor under the same conditions.

In photography, the sensitivity to light is measured by using a yardstick called ISO (International Standards Organization). Most point-and-shoot digital cameras have a sensitivity range of about ISO 50 to ISO 100 (at the low end) up to a maximum of ISO 400 (at the high end). Fuji has introduced a compact digicam with its SuperCCD sensor that includes two light-sensitive areas per pixel, and it boasts an ISO 1600 maximum sensitivity, but virtually all other non-SLR cameras top out at ISO 400.

REMEMBER

In contrast, digital SLRs - with their more sensitive sensors - commonly have ISO settings of up to ISO 800. Many are capable of ISO 1600 or even ISO 3200. There's a downside to this extra speed, as you see in the section "Reducing noise in your photos," but in general, the added sensitivity is a boon to people who want to shoot photos in dim light, take action pictures, or need to stretch the amount of depth-of-field available.

Reducing noise in your photos

Noise is that grainy look digital photos sometimes get, usually noticeable as multi-colored speckles most visible in the dark or shadow areas of an image. Although you can sometimes use noise as a creative effect, it's generally a bad thing that destroys detail in your image and might limit how much you can enlarge a photo before the graininess becomes obtrusive.

The most common types of noise are produced at higher sensitivity settings. That's because cameras achieve the loftier ISO numbers by amplifying the original electronic signal, and any background noise present in the signal is multiplied along with the image information. As you see in the Figure 1-4, a relatively low ISO value of 200 produces an image that's virtually free of the noise, but jumping the sensitivity to ISO 1600 produces a lot more noise - even though a person used a digital SLR for both pictures.

REMEMBER

One reason why point-and-shoot digicams rarely have ISO settings beyond ISO 400 is that the noise becomes excessive at higher ratings, sometimes even worse than you see in the lower example at right. However, you can boost the information that the bigger dSLR sensors capture to higher ISO settings with relatively lower overall noise. I've used digital SLRs that had less noise at ISO 800 than some poor-performing point-and-shoots displayed at ISO 100. Obviously, the larger sensors found in dSLRs score another slam-dunk in the noise department and make high ISO ratings feasible when you really, really need them.

Noise doesn't always result simply from using high ISO settings: Long exposures can cause another kind of noise. Although some techniques can reduce the amount of noise present in a photo (as you discover in Chapter 2), by and large, digital SLR cameras are far superior to their non-SLR counterparts when it comes to smooth, noise-free images.

REMEMBER

Thanks to the disparity in size alone, all sensors of a particular resolution are not created equal, and sensors with fewer megapixels might actually be superior to higher-resolution pixel-grabbers. For example, most older 6-megapixel dSLRs produce superior results to the newest 8-megapixel non-SLR digicams. I've seen results from one $3,500 4.3-megapixel pro-level dSLR that run rings around the best images possible from an $800 EVF model with an 8-megapixel sensor. So no matter how many megapixels a point-and-shoot camera's sensor can hoard, that sensor isn't as big as a dSLR's. And when it comes to reducing noise, the size of the sensor is one of the most important factors.

Reclaiming depth-of-field control

Depth-of-field is the range over which components of your image are acceptably sharp. In general, being able to control the amount of depth-of-field is a good thing, because having more or less depth-of-field gives you creative control over what is sharp and what is not. You might prefer to zero in on a specific subject and let everything else remain blurry. Or you might want to have everything in your frame as sharp as possible.

To understand how dSLR cameras give you more control over depth-of-field, you need to understand the three factors that control this range, which I outline in Table 1-1.

Point-and-shoot digital cameras offer very little control over depth-of-field, because, unless you're shooting an extreme close-up (see Factor 1 in Table 1-1), virtually everything is in sharp focus (despite Factor 2). This condition (which can be a bad thing if you're trying to use focus selectively) is due to Factor 3: Non-SLRs use that tiny sensor, which calls for lenses of a much shorter focal length.

So, a point-and-shoot digital camera might have a 7.5mm to 22.5mm 3X zoom lens that provides a slightly wide-angle to slightly telephoto field of view. A digital SLR with the largest (24 x 36mm) sensor might need a 35mm to 105mm zoom to provide the same perspective.

Yet, depth-of-field is dependent on the actual focal length, not the equivalent. So that point-and-shoot camera's lens, even at its longest telephoto position, provides more depth-of-field than the dSLR's same-perspective zoom at its widest angle. So much is in focus with a non-SLR digital camera that, in practice, you have very little control over depth-of-field, except when shooting close-up pictures from very short distances.

Even if you're shooting relatively close with a point-and-shoot camera, as in Figure 1-5, judging and using depth-of-field can be tricky. The house in the background is too sharp, and because this particular digicam didn't have great close-up capabilities, the ice-covered berries in the foreground aren't sharp enough. Shooting the same scene minutes later with a dSLR equipped with a macro lens shows how control over depth-of-field can be used creatively to isolate a subject (see Figure 1-6).

Because of the longer focal lengths mandated by the dSLR's larger sensors, these cameras offer the photographer an important creative tool.

In Chapter 6, I explain depth-of-field in more detail.

(Continues...)

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Excerpted from Digital SLR Cameras & Photography For Dummies by David D. Busch Excerpted by permission.
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