Your next electronic imager will let you shoot photos faster and better.

Most digital cameras today have megapixels galore, a large LCD viewer screen, and long battery life, and take fine pictures in good light. To stand out, new models are adding features to improve performance in more difficult shooting situations. These cameras claim to conquer such challenges as shooting that birthday cake with only the light from its candles, or capturing the detail in a face photographed in front of a bright window.

We upgraded our tests to address those more ambitious claims and higher expectations. The results revealed a wider range of performance than in past reports.

Our tests also revealed some overlap in performance between point-and-shoots,  comprising subcompact, compact, and superzoom cameras, and SLRs, the bigger and pricier cameras that use interchangeable lenses.

Here are some performance attributes we consider important and details about our new tests:

Image quality. Our new image quality scores combine the judgments of our experts with software analysis for sharpness; color accuracy in a variety of conditions, such as daylight and artificial light; and other attributes, including those covered below.

Dynamic range. A camera’s prowess at capturing gradations of light and dark can determine the success of shots that include widely varying light conditions. A new performance score, dynamic range, reflects that capability.

The best performers in our dynamic range tests are capable of rendering detail well in very dim as well as very bright areas of the image. The worst all but obliterated those finer points at both extremes.

Shooting in low light. The ISO setting is a performance specification that helps you gauge how well the camera can shoot indoors or at dusk. We now measure how high an ISO setting you can use on the camera without enlarged images becoming overly grainy, fuzzy, or speckled.

At ISO settings above a fairly modest 400, many point-and-shoots produced images that had flaws. Most SLRs produced images at 800 ISO that were good enough to yield a satisfying 8x10 print.

How versatile? Among other attributes, this judgment considers such useful features as the presence of an optical viewfinder, exposure compensation, and a movable LCD, and the range of ISO and other settings.

If you already know the features you’re looking for, you might want to skip ahead to our Ratings. If this is your first digital camera or you just want a refresher on what to look for, read on.

The leading brands are Canon, Casio, Fujifilm, HP, Kodak, Nikon, Olympus, Panasonic, Pentax, Samsung, and Sony. Other brands come from electronics, computer, and traditional camera companies. General Electric is a recent entrant.

A growing number of cameras are subcompacts that fit in a pocket. Prices for subcompacts have declined so much recently that they’re virtually the same as those for compacts. Another bright spot: The performance of subcompacts, which has lagged behind that of larger cameras, has improved. More than half the subcompacts we tested had excellent dynamic range (the ability to properly expose an image that displays the widest range of tonal gradations), a performance level better than many of the bigger cameras we tested. Price: $140 to $300.

Mainstream compacts are too big to pocket but small enough for most handbags. The ones we tested recently weigh 6 to 14 ounces. Price: $80 to $500.

Super-zoom cameras are characterized by a very long zoom range, 10x or greater, good for sports or nature shooting. While traditionally larger and heavier than compact digicams, a few new models are designed to be smaller and lighter than older models. Some models in our latest Ratings use light- weight parts to get their weights down to as little as 12 to 14 ounces. Price: $250 to $700.

More serious cameras have the versatility and power to capture fast action or create photographic art under the most demanding light conditions. SLRs, the largest and heaviest type, offer the most versatility and power, including interchangeable lenses. Price: $500 to $1,700 for consumer models; professional models can cost thousands.

Digital cameras are distinguished by their resolution, how many pixels, or picture elements, the image sensor contains. One mega--pixel equals 1 million picture elements. A 7-megapixel camera can make excellent 8x10s and pleasing 11x14s. There are also 8- to 12-megapixel models, including point-and-shoot ones. Those are well-suited for making larger prints or for maintaining sharpness if you want to use only a portion of the original image. Professional digital cameras use sensors with as many as 21 megapixels.

Most digital cameras are highly automated, with features such as automatic exposure control (which manages the shutter speed, aperture, or both according to available light) and autofocus.

Instead of film, digital cameras record their shots on flash-memory cards. CompactFlash (CF) and Secure Digital (SD) are the most widely used. Once quite expensive, these cards have tumbled in price, a 1-gigabyte (GB) card can now cost less than $15. Other types of memory cards used by cameras include Memory Stick Duo and xD.

To save images, you transfer them to a computer, typically by connecting the camera to the computer’s USB or FireWire port, or inserting the memory card into a special reader. Some printers can take memory cards and make prints without putting the images on a computer first. Image-handling software like ACDSee, Adobe Photoshop Elements, Corel Paint Shop Pro Photo, or Ulead PhotoImpact lets you resize, touch up, and crop digital images using your computer. All digital cameras work with Windows computers and Macs.

The file format commonly used for photos is JPEG, which is a compressed format. A select few high-end cameras can save photos in the uncompressed TIFF format, but this setting yields huge, storage-hogging files. Other high-end cameras have a RAW file format, which yields the image data with no processing from the camera and is often uncompressed.

The optical viewfinder is becoming increasingly rare, replaced by larger color LCD viewers. (Some are now as large as 3.5 inches.) These displays are accurate in framing the actual image you get, better than most optical viewfinders, but they might be hard to view in bright sunlight. You can also see shots you’ve already taken on the LCD viewer. Most digital cameras provide video output, so you can view your pictures on a TV screen. Some even include HDMI outputs (either on the camera body or the camera dock) that can be attached to an HDTV. But the cords or docks may cost extra.

Most point-and-shoots let you capture video and sound. Some record video in the high-quality MPEG4 format for up to 30 frames per second, up to the memory card’s capacity. The ability to record video in high-definition (HD) resolution (though not in MPEG4 format) is starting to show up.

A zoom lens provides flexibility in framing shots and closes the distance between you and your subject, ideal if you want to quickly switch to a close shot. The typical 3x zoom on mainstream cameras goes from a moderately wide-angle view (35 mm) to moderate telephoto (105 mm). You can find cameras with extended-zoom ranges between 10x and 20x, giving added versatility for outdoor photography. Other new cameras go down to 24 or 28 mm at the wide-angle end, making it easier to take in an entire scene in close quarters, such as a crowded party.

Optical zooms are better than digital zooms, which merely magnify the center of the frame without actually increasing picture detail. Sensors in digital cameras are typically about as light sensitive as ISO 100 film, though many let you increase that setting. (At ISO 100, you’ll probably need to use a flash indoors and in low outdoor light.) A camera’s flash range tells you how far from the camera the flash will provide proper exposure.

Red-eye reduction shines a light toward your subject just before the main flash. (Computer editing of the image can also correct the problem.) With automatic flash mode, the camera fires the flash whenever the light entering the camera registers as insufficient.

More and more cameras, including many with powerful telephoto lenses, now come with some form of image stabilizer. Stabilizers compensate for handheld camera shake, letting you use a slower shutter speed than you otherwise could without producing blur due to hand shake. But an image stabilizer won’t compensate for a subject’s motion.

Many new compacts come with full manual controls, including independent controls for shutter and aperture. That gives serious shutter-bugs control over depth of field, shooting action, or shooting scenes that have tricky lighting.

Face recognition is a handy feature that makes sure faces are in focus and properly lighted. Sony’s Smile Shutter feature takes face-detection technology a step further by shooting a photo of the subject only when he or she smiles.

You can’t always depend on salespeople to help you choose the right camera. CONSUMER REPORTS readers indicate that the quality of in-store help is all over the map. Indeed, when our reporter shopped at mass merchandisers, as many consumers do, one salesperson told him that there was no difference between digital and optical zoom (optical is far more useful). Here’s what you need to know:

Shop by brand. Before diving into specific models, consider some characteristics by brand, culled from our years of digital-camera tests. For example, Fujifilm offers image sensors with proprietary technology that produce high image quality at high ISO settings. Kodak emphasizes simplicity and ease of use. Canon, Nikon, and Olympus offer full lineups for every type of user.

Beware the megapixel wars. Despite the increasing prevalence of 8- , 10- , and 12-megapixel cameras, 7 megapixels is all the resolution most people need. Higher resolution doesn’t necessarily produce better prints. Lenses and other design factors are important, too. In our tests, some models with 7 megapixels had excellent print quality, while some with 10 megapixels had fair or good quality. If you often crop or drastically enlarge your images, get at least 8 megapixels.

If you need high resolution and impeccable quality, choose one of the compacts or SLRs that had excellent print or image quality in our tests. Shooting at a higher resolution without using a compressed format such as JPEG can fill your memory card and hard drive more quickly. Recently, though, more cameras can record on a new, higher-capacity card known as SDHC.

Weigh zoom trade-offs. Another feature to consider is an optical-zoom range greater than the 3x found on most cameras. (A zoom lens’s range is the ratio of its highest telephoto focal length to its lowest wide-angle length.)

Greater zoom means greater weight and bulk, though a few pricey compacts manage to squeeze 10x into a compact package. Don’t compromise on price, size, and weight for a zoom range greater than 3x unless you often shoot distant subjects such as wildlife and sporting events or need a very wide-angle lens for landscapes or group portraits.

A greater proportion of compacts and subcompacts have a range above 3x, with some as high as 7x, enough to make a distant figure fill the frame. Super-zoom cameras typically have a 10x or greater zoom range. An SLR’s zoom range depends on the lens mounted on it; the typical kit lens sold with most models offers about 3x magnification, though upgraded kit lenses offer more.

How much control do you want over exposure and composition? Cameras meant for automatic point-and-shoot photos, with a 3x zoom lens, will serve casual shooters as well as dedicated hobbyists much of the time. Super-zoom cameras with an optical zoom range of 10x or more, which lets you bring outdoor subjects close, are good for those who shoot sports and nature subjects.

Spring for an SLR if you want those attributes and more, and can afford a variety of lenses.

Among point-and-shoot cameras with built-in lenses, the highest ISO light-sensitivity setting has generally been 400, too low to make sharp, hand-held shots in dim light without a flash. Some modestly priced models have begun featuring settings of 1600 or even 3200, but results can be grainy and noticeably worse than those shot at equivalent settings using SLRs and the priciest point-and-shoots.

Battery type and life. All digital cameras run on rechargeable batteries, either an expensive battery pack or a set of AAs. In our tests, neither type had a clear performance advantage. The best-performing point-and-shoot cameras offer around 500 or more shots on a single charge, while the worst manage around 125. SLRs can record even more photos per charge.

For some users, it may be more convenient to own a camera that accepts AA batteries. You can buy economical, rechargeable cells (plus a charger) and drop in a set of disposable lithium or alkaline batteries if the rechargeables run down in the middle of shooting.

Forgo the extended warranty. Overall, digital cameras have been among the most reliable products in our subscriber surveys. Only about 5 percent of those purchased between 2004 and 2007 have been repaired or had a serious problem. We don’t think it pays to buy an extended warranty for a digital camera.

Once you’ve established the performance priorities that you need from a camera, consider these factors:

For point-and-shoot cameras:
Select the right type. If pocketability is a priority, get a lightweight subcompact. They’re not for serious shutterbugs, but they’re far more capable than a camera phone. If you want better image quality or more control over images, get a compact. More compacts than subcompacts had very good image quality, and more often zooms greater than 3x. If zoom is a priority, get a superzoom. They’re bulkier but have at least 10x zoom; some newer models go up to 20x.

Match performance to your needs. Image quality is a camera’s most important performance attribute. Differences in sharpness are what’s most noticeable among models of varying scores.

Consider what you’ll print. If you shoot mainly 4x6s and rarely crop pictures, most cameras that have 7 or 8 megapixels should be fine. If you print poster-sized shots or do major cropping, a 10- or 12-megapixel model makes more sense.

For SLRs:
Select an SLR level. If you’re thinking of trading up from a point-and-shoot, a basic SLR is the place to start. There are fewer controls, easier-to-read graphic interfaces, and fewer options. Advanced SLRs are more rugged, weather-resistant, and versatile, but also bulkier and heavier.

Know the system and brand. When you buy an SLR, you’re potentially buying into a family of lenses and integrated accessories, such as external flashes. Those from the camera maker are often pricier than ones made by other companies, but they will be compatible and will take full advantage of the camera’s features.

Don’t skimp on performance. While all the SLRs we tested are competent, narrow your choice to those models that are at least very good for image quality and versatility, and can shoot to at least 800 ISO without image flaws. That includes most rated models. Battery life is important too; most better performers offered more than 400 shots per charge.