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If you find yourself in a situation in which the lighting isn’t quite right for your picture, it’s time to bump up the camera’s ISO value. Remember that not all cameras come with ISO adjustments, so review your user manual to see if this applies to your particular model. You’ll probably find it in the onscreen menu system, displayed in the LCD screen on the back of your camera.
Here are some situations in which you might need to increase the ISO:

• You’re shooting in a low-light situation, such as early evening or indoors Naturallight photos have a certain appeal, and by increasing the light sensitivity of your camera you may be able to shoot a picture without using the flash at all. Using natural light can eliminate harsh shadows and produce more natural colors.
• Your subject is too far away for the flash to have any effect During the day you might be outdoors and want to take a picture of something, but there’s not quite enough light—such as in winter or during very overcast conditions. Your camera wants to use a flash, but your subject is just too far away. The flash on your digital camera has a very limited range. So to properly expose your picture, you need to use “faster film”—that is, increase the camera’s ISO setting.
• You’re shooting at night Most digital cameras have very little ability to take pictures at night or in near total darkness. A few models can extend the shutter to about half of a second, but that’s about it. As a result, if you want to capture anything at all with a night shot, you’ll need to increase the camera’s light sensitivity to maximum.

If night photography interests you, investigate what I refer to as “performance” digital cameras—cameras that include manually adjustable shutter speeds and apertures. Cameras like the Nikon CoolPix 995, the Olympus C-4040, and the Canon PowerShot G2 are the sorts of models that are better equipped to deal with very low light such as you’ll encounter at night. Using more full-featured cameras let you perform long exposures for light trails, glowing illuminated signage, and other special effects.

You can use the ISO control built into your digital camera to vary its sensitivity to light and thus mimic the effect of using different grades of 35mm film. This can come in handy in a number of situations, such as when you’re shooting in particularly high or low light levels. Remember a few key facts about your camera’s ISO ratings, though:

• It’s not a real ISO adjustment, in the sense that your camera doesn’t have real film. Each camera maker has a somewhat different way of implementing this feature, but they all use ISO numbers since that’s comparable to 35mm film, which most people are at least a little familiar with.
• Don’t leave your camera set at the highest ISO all the time. Some folks think that by setting their cameras to the highest sensitivity, they’ll be prepared for anything and won’t have to muck with the camera menu when they’re on the go, trying to take pictures. In reality, boosting your CCD’s sensitivity to light also increases the amount of digital noise you’re capturing. More ISO means more fringing, artifacts, and digital detritus. Sometimes that’s unavoidable, but stick with the lowest ISO value you can get away with most of the time.

All that talk about f/stops, shutter speed, and ISO settings may seem irrelevant to your digital camera, but it’s not—all cameras use these concepts, even though they’re sometimes disguised fairly well. The main difference between a digital camera and a chemical film camera, of course, is the fact that digicams don’t use film. That means you never load anything that has a specific ISO value into the camera. So how does the camera actually work? Simple. When light enters the camera at the moment of exposure, it doesn’t hit light-sensitive silver halides that are fixed in a chemical broth. Instead, the light hits a computer chip called a charge coupled device (CCD). The CCD is light sensitive, and each of its many pixels register changes in light just like the film’s many grains of silver react individually to light. In other words, the silver grains in film and the pixels in a CCD are essentially the same thing. They contribute to your picture in the same way, and both are the smallest components that make up your picture.
The CCD makes a picture by noting the variation in light rays that travel through the camera lens. The CCDs pass this information on to the camera’s microprocessor in the form of varying electrical charges. The image is transformed into digital bits and stored on a memory card. Your camera’s CCD functions like the film in a 35mm camera, except that it differs in one important way—you can’t swap the CCD out of your camera and insert one with more light sensitivity for low-light photography. The CCD is a permanent part of the camera. Camera makers understand that you might need to change the camera’s light sensitivity on occasion, though, and that’s why many cameras can have their ISO rating “adjusted” on the fly, whenever you want. In essence, what this does is allow you to “turn up” or “turn down” your camera’s sensitivity to light.

So far so good—but there’s one other aspect to consider, and that’s the fact that camera lenses can change the diameter of their aperture, thus letting in more or less light as needed. The size of a camera’s aperture at any given moment is called the f/stop, or sometimes referred to as the f number of the lens. F/stops are represented by numbers that start with f/—like f/2, f/5.6, and f/11. The larger the number, the smaller the opening, so an f22 is very, very small (not much light gets through to the film), while a lens set to f/1.2 is a huge opening that floods the film with light. Changing the camera setting by a “whole” f/stop, such as from f/5.6 to f/8 or from f/11 to f/16, doubles or halves the available light, depending upon which way you’re going.

If you adjust a lens from f/8 to f/11, for instance, you’ve reduced the light by half. As you reduce the shutter speed, you need to increase the diameter of the aperture in order to have enough light to take a properly exposed picture. Of course, there’s a relationship between aperture, shutter speed, and your film’s ISO rating. At a given film speed, you can take a picture with a specific aperture/shutter combination. If you double the film speed without changing the lighting conditions, though, you have to adjust the aperture and shutter speed so that you still get a properly exposed picture. And perhaps most importantly for us, suppose you are in the situation I describe next.

You want to take a picture of frolicking lions at the zoo near dusk. The aperture is wide open at f/2—it won’t open any farther. Nonetheless, your camera needs to use the relatively slow shutter speed of 1/15 second to take the shot. You know the image would be a blurry mess at that sluggish shutter speed, so what is there to do? Take a look at your film speed. It’s ISO 100 film. Well, you might be in luck. If you’re willing to pop the film out of your camera and put in film that’s two f/stops (often, just called “stops”) faster, you can keep the aperture at f/2 and change the shutter speed to 1/60. That’s probably good enough to get the shot. Just do it quickly—it isn’t getting any brighter out, and if you dally, you might find you need to increase the speed by three stops by the time you get the film loaded and ready to go.

As you no doubt know by shopping for film, not all canisters of 35mm film are alike. Film is differentiated principally by its speed, or ISO number.
A film’s ISO number refers to how sensitive it is to light. The lower the number, the less sensitive—requiring long exposures or very bright scenes.
The International Organization for Standardization (ISO) is the group that helped establish how the number scheme works. Film around the world uses ISO numbers, so you can buy it anywhere, and it’ll all work the same. In the United States, photographers used to call this system ASA, which stood for the American Standards Association. That term was essentially abandoned about 20 years ago, so if you want to be considered a gristled old geezer, you can refer to ISO numbers as “ASA.”
A fairly typical ISO number for ordinary daylight photography is ISO 100. Increasing the ISO to 200 doubles the sensitivity of the film; dropping back to an ISO of 50 halves the sensitivity of the film.
This film sensitivity has a tangible effect on the mechanics of photography. To see why, look at Figure 2-1; this diagram shows a typical camera body as a picture is taken. The lens is equipped with a diaphragm—called an aperture—that has a certain diameter and consequently is designed to allow a specific amount of light through to the film. With ISO 100 film in specific lighting conditions (say, at midday) the shutter might need to open for a 250th of a second (1/250) to adequately expose the picture.
But what happens if we instead try to take the same picture with ISO 200 film? The film is exactly twice as sensitive to light as the previous roll of film. And that means, all other things being equal, that we need to leave the shutter open for only half as long (a 500th of a second, or 1/500) to take the same picture.
That’s not all. Suppose you’re trying to take a picture in late afternoon—when there isn’t as much light available? You might need to leave the shutter open for 1/30 in that situation to gather enough light. That shutter speed is a bit on the slow side, though. Not only might you jiggle the camera as you’re taking the picture (it’s hard to hold a camera steady for 1/30), but your subject might move as well, causing a blurry picture. You can probably guess what the solution is—stepping up to ISO 200 film will enable you to grab that picture at a much more reasonable 1/60, and ISO 400 would halve the shutter speed yet again, to a crisp 1/125.

Traditional cameras rely on good old-fashioned film. But what is film, really? It’s just a strip of plastic that has been coated with a light-sensitive chemical. The chemical soup on the film is loaded with grains of silver halide. When exposed to light, the silver halide reacts, and that is the essence of photography. The longer the film is exposed to light, the more the silver is affected. The two kinds of film in common use today are negative and slide film. They work a little differently, but the end result is similar. When you use color negative film, also referred to as reversal film, the film itself becomes a “negative” image of the scene you photographed. After processing—which includes letting the film sit in a chemical bath that coaxes the grains of silver to visually materialize on the film—the negative is used to create positive prints of the scene. It’s a two-step process, and one that is highly subjective. When creating prints from negatives, photo-finishers often tweak the picture to improve its appearance. Of course, what the corner shop considers an “improvement” may not be what you were trying to achieve, and that explains why your pictures never seem to benefit from filters, exposure changes, or any of the other corrections you try to make when taking pictures.
But I digress. The other kind of film is simple slide film. This is a color positive development process—after fixing the slide film in its chemical bath, the film becomes slides that can be held up to the light to display images.
No matter what kind of film you have, it eventually needs to be exposed to light. When you take a picture, you obviously press the shutter release. The shutter release instructs the camera to open a diaphragm in the lens for a brief period of time and then close again. If all went well, that was just long enough to properly expose the film.
If you want to shoot with 35mm film, scan the results, and then edit and print the results on your PC, you might want to work with slide film. Slides are more exacting—they require you to nail the exposure fairly precisely, but they’ll better represent what you actually photographed instead of the local photo shop’s vision of what you photographed.

Every hobby has its accessories. I sometimes joke that my dive buddy only became interested in scuba diving after she discovered that scuba gear was a whole new way to spend money. While there’s no doubt some truth to that, it’s also true that there are some things you really need to buy to accompany any activity, and digital photography is no exception. Here’s a short shopping list of things you might consider buying as you get more into shooting digitally:

• A camera It goes without saying that you need a camera, but don’t rush into the purchase. You can even use a 35mm camera to begin with, and scan the images into the PC for editing and printing. If you’ve read the previous sections of this chapter and decided what features are important to you, you can shop like a pro.
• An adequate PC Crunching data to process digital images takes a bit more horsepower than you might be used to when working with Word or Excel. I suggest using a Pentium III–class PC with no less than 128MB of RAM. If you want to work with really big images—like 6-megapixel pictures—then consider 256MB of RAM. You might be surprised to learn that more memory is generally more useful than a faster processor.
• Batteries Digital cameras are power hogs. I highly recommend buying two sets of NiMH rechargeable batteries, since they’ll pay for themselves before you can say “alkaline.” If your camera didn’t come with an AC adapter, I suggest that you buy one from the camera vendor’s accessories store so you can power the camera when you’re transferring images to the PC or displaying images on a TV.
• Memory Buy the biggest memory card you can afford. The measly 8MB memory card that came with your camera won’t last a day when you’re on vacation, so having a 128MB or 256MB card is almost essential. A spare card, if it’s in the budget, can keep you going when you fill up your main card far away from your PC.
• Image editing software Your camera probably came with some rudimentary image editor, but it may not be up to the task. Try a few out, and buy the image editor that you like the best. I typically use Paint Shop Pro (from www.jasc.com), for instance.
• Printer Get a good color inkjet printer and premium photo paper. Don’t skimp on this step—when the time comes to print your pictures, why bother having a good camera, this book, and taking the time to improve your photo skills if you’re going to print pictures on a budget printer with lousy paper?
• Tripod If you want to extend your photography into the world of close-ups or long-range telephoto images, a tripod is a necessity. It needn’t be large or heavy, because most digital cameras are significantly lighter than their 35mm counterparts.
• Lenses and filters The time may come when you want to take pictures—like extreme close-ups, wide-angle shots, or extreme telephotos—that are beyond the range of the lens that came with your camera. Likewise, you might want to reduce glare or add other special effects to your images. If that’s the case, you want lenses and filters for your camera. You may not need them right now, but consider them an advanced purchase for later on.
• Camera bag Choose a bag that lets you arrange your camera and accessories in a way that they’re protected from theft and damage, but easy to use when the time comes to shoot a picture. Look for bags that don’t really look like they’re holding camera gear—that might make them less of a target for thieves.

Getting images out of your camera is just as important as taking the pictures to begin with. If you like to view your freshly shot images on a television or want to record them, slide show style, directly to a VCR, then you should definitely consider a camera with a video-out port. Using an ordinary RCA-style composite video cable, you can connect the camera to a TV, VCR, or some other video display unit. ages painlessly, especially compared to the more traditional (and now virtually obsolete) serial cable.
Some cameras include even more convenient solutions, like adapters that accept the removable media card and connect to the computer directly. The advantage with these devices is that you can transfer images without draining the camera batteries, and transfers are often easier to do, since you avoid using arcane transfer software and instead just drag and drop images from a folder on the Windows desktop.

Since digital cameras are part computer, they can be programmed to do some neat tricks that were inconceivable with traditional 35mm cameras. Few of these effects are necessary; in fact, I’d choose a camera based on solid features like the zoom, lens quality, and overall handling before I looked too hard at whether the camera included a video mode or sepia tint. Nonetheless, these are some of the effects you may see:

• Panorama mode This feature takes wide-screen-style images either by automatically cropping the top and bottom off an image or by letting you stitch together several pictures to create one oversized one.
• Movie mode Some cameras can capture short, low-resolution video clips as well as still images. Don’t confuse this with high-quality digital video, though—the results are strictly for Web pages.
• Tint modes With special settings, you can take black-and-white or sepia-tinted stills.

Remember, though, that you can achieve the same effect in an image editor on the PC after the picture is taken, so you aren’t losing anything if your camera lacks this feature. In fact, I’d say it’s better to start with a full-color image; that way you can do whatever you like to it later and always have the high-quality original to fall back on.

Almost all digital cameras come with a built-in flash. The real issue is how well the flash works. Check to see what the maximum range of the flash is and if it works when the camera is in macro, or close focus, mode. You might also want a flash with special features like these:

• Red eye reduction This mode preflashes the subject to try to minimize reflected light from the pupil known as red eye.
• Force/fill Force or fill flash is used to reduce shadows outdoors or in otherwise adequate lighting when the flash might not fire.
• Rear curtain flash This mode fires at the end of a long exposure. It comes in handy at night so that light trails precede the main subject, illuminated by the flash.

Some cameras also come with sync ports or hot shoes that allow you to connect more powerful, external flash units.