A Complete Guide to Buy a DC

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DC=Digital Camera

If you're still using a film camera, or have an older digital camera, it's time to upgrade. Technology has moved even faster in the digital camera arena than with PCs in the last couple years. Digital offers many advantages over film, such as direct computer download, no film or developing costs, immediate review of pictures to be sure you got the shot, and the ability to edit your images with software like Roxio's PhotoSuite. And the latest digital cameras even rival film for quality and features.

Perhaps the only catch is the staggering variety of options from which to choose. So here's a guide to help you decide if it's time to buy, and the key features to look for.

Category

Before looking at the details, decide on the general price range that's right for you.

Basic point-and-shoot digital cameras that are excellent for families, taking on trips and other uses can be had for $200-$400. These cameras are typically in the 1.3-to-3.3 megapixel range, and often quite compact in size.

Mid-to-high-end cameras with more resolution (typically 3.3-to-4 megapixels) and features such as manual controls, powerful zoom lenses, and flash hot shoes, cost about $400-$800.

At the top end of the spectrum, digital SLR cameras with interchangeable lenses just like their film counterparts, are starting to appear in the $2,000 price range and should continue to decrease in price. These cameras offer true film-like flexibility for the serious hobbyist, and resolutions up to 6 megapixels that rival that of film. If you don't need interchangeable lenses, cameras in the $1,000 price range offer similar features and image quality.

Resolution

Resolution (stated in megapixels) is a major determinant of both price and image quality. However, while it used to be a given that you should buy the highest resolution camera you could afford, with so many cameras now in the 4-to-6 megapixel range, it's arguable that resolution is no longer as much of a consideration. For the vast majority of people, a 4-megapixel camera is probably good enough for everything they need, including 8x10 prints. Only if you need to crop your images way down, or print them poster size, do you have to buy the highest resolution camera available.

High-res digital cameras (in the 5-to-6 megapixel range) can be very expensive ($700 to $1,000), but these cameras generally also have the best optics and feature sets. For $300 to $500, you can get a good 2-, 3- or even 4-megapixel camera with fewer bells and whistles.

Of course, when considering price, remember all the money you'll save on film and developing! (Prints can cost more, but you'll likely print far fewer images-just the ones you really like, for a net savings overall.) And even though a high-resolution camera may cost more now, you'll likely keep it longer.

Just what is a megapixel? It's short for millions of pixels, so a 2-megapixel camera produces an image with approx 2 million pixels (typically 1,600x1,200=1,920,000.)

How many pixels is enough? If you just want to display your pictures on a computer screen--to e-mail to friends, or put on CDs and Web pages--then 1,280-by-1,024, or about 1.3 megapixels, is all you can really use. Going with a slightly larger camera (2.1 megapixels) will give you the flexibility to crop your images, and get decent print quality, for relatively few additional bucks.

If print quality is your primary concern, things get more complicated. You'll need to decide on the maximum print size you expect to use (such as 5x8 or 8x10), and note the resolution of your printer (such as 600 or 720 dots per inch (dpi)). But you can't just multiply 8 and 10 inches by 600 dots to determine that you need an image file 4,800x6,000 pixels (which is lucky, since that is far beyond the capability of most digital cameras!).

Image file resolution is different from print resolution since most printers use solid-color dots (cyan, magenta or yellow) and each dot can only be one of these colors. With the camera image, a pixel can be any of 16 million colors. To create the illusion of more colors, the printer actually prints patterns of these dots (yellow and blue looks like green). So if you send a 720 pixel-per-inch image to a 720dpi printer, you'll be throwing away color data. For best results, the rule of thumb is to divide the resolution of your printer by 2 or 4 to get the image resolution you'll need. For example, for a 720dpi printer, your image file should have 360 or 180 pixels per inch. If your printer is 600dpi, use 300 or 150 pixels per inch.

You will see a small difference in print quality between divisors of 2 or 4, but the larger image will take you longer to manipulate and print. So do a test run on your printer to see the differences, and then decide which resolution you prefer.

Once you know the image resolution you need in pixels per inch, you just multiply it by print size to get the camera resolution you'll need. For example for an 8x10 print at 180dpi, you need a camera capable of shooting at least 1,800-by-1,440 pixels, or about 2.5 megapixels. Again, we recommend rounding up (in this case to 3 megapixels), so you can crop photos where needed.

Another important point is that sheer number of pixels is not the only component of resolution--image quality counts too. Two cameras producing the same image file size might produce very different quality in terms of image detail. Image quality at a given size can be affected by the quality of the lens, any manipulation done by the camera (rescaling and color calculations) and the compression used on the image.

Most cameras use some kind of compression, typically JPEG, when saving images, and have two or more different compression options (high, medium, or low quality, for example). No matter which setting you use, the resulting image size in pixels remains the same, but the file size (in kilobytes) will be smaller for the more-compressed images (lower quality). To compress the image, some resolution (detail) is thrown away. Of course, the more compression used, the more images you can capture before the memory card is filled.

Many of the high-end cameras include an uncompressed (usually TIF format) or a RAW file format option. Both promise the 'best' quality image the camera can produce, though the files are much larger, and will often take the camera much longer to save.
With the RAW format, the actual data from the cameras CCD is stored in the file. Because of the way cameras work, each pixel on a CCD only records one color (usually Red Green or Blue, or Cyan, Magenta or Yellow) rather than TIF or JPEG which stores three colors per pixel. During conversion to TIF or JPEG, the single color is combined with information from surrounding pixels to create an interpolated color for the pixel. Also, many cameras capture 12-bit information for a pixel (rather than 8-bit) and this information is saved in the RAW file. Usually you can't rewrite these RAW files, which prevents you from accidentally overwriting the original files. However it's a tradeoff whether to use these uncompressed formats or the highest quality JPEG format. You have to weigh the image quality difference with the performance and memory requirements of saving in uncompressed formats.

Generally, the better the optics and higher-priced the camera, the better image quality you will get. Which brings us to a discussion of lenses.

Lenses

Producing good quality optics for digital cameras can be a challenge. Considering the small size of most CCD imagers versus the size of a typical 35mm film frame, the digital cameras lens must be of very good quality to produce a good image. Most digital cameras are of the range-finder, fixed-lens type. The choices in lenses continue to increase, and you can also get add-on lenses for some cameras (notably wide-angle lenses for Nikon's CoolPix 900 family of cameras, and the add-on lens for the Olympus E-10/20) but add-ons aren't available for all cameras, and for the most flexibility you will want to look at the more expensive digital SLR cameras (like the Canon D-60 and Nikon D-100.)

Digital cameras have typically been less light-sensitive than film cameras, which means that for a given quality lens, you will not be able to get as much image detail, unless shooting in very bright light. So also check out the ISO ratings of the cameras you are considering. Some offer the ability to capture at 400 or 800, although the results may be noisy.

When comparing lenses, we are most interested in the field of view of a lens (how wide or narrow it is). Historically, the focal length of a lens has been used as an indication of field of view. For 35mm cameras, 50mm is considered "normal," 28mm is considered "wide," and 150mm is "long." While focal length is measured differently in a digital camera, most manufacturers quote 35mm equivalents.

The most common optical zoom lenses are 2X and 3X. The multiplier is the longest lens setting divided by the widest (i.e. 38 to 120 mm is 3X, 38 to 75 mm is 2X)

A few cameras come with truly long optical zoom lenses, 6X or 10X. However be aware that as the lens gets longer, it gets more difficult to hold the lens steady enough while the picture is being taken. At least one manufacturer includes an image stabilization system in their long lens camera precisely because of this problem. Also, some camera lenses are better than others. Many low-to-medium-end cameras suffer from problems with barrel distortion (the image sides appear to be slightly bowed.) This is most notable in the wide angle end of the lens, and you should check reviews for the cameras you are interested.

It's important to distinguish between optical and digital zoom. With optical zoom, lenses move to scale the image (technically speaking, the focal length of the lens is being changed), whereas digital zoom scales the image electronically, without actual additional picture information. There is therefore a big difference in quality between these two techniques. Optical zooms are always preferable, although many cameras offer a combination of both, using optical up to a point, then switching to digital. You can always scale your image later if needed with computer software, there is no need to do it in the camera.

Many digital cameras offer a Macro feature. This is the ability of the camera to focus on objects very close to the lens. If you plan to take close-ups you will want to make sure the camera has Macro capability.

Camera Speed

The other big difference between digital and film cameras is picture-taking speed. While film camera owners are used to snapping away repeatedly with no noticeable lag time between shots (except perhaps for flash recycling), digital cameras can be downright slow in comparison. These delays can be noticeable when turning the camera on (startup time), the time between depressing the shutter and taking the picture (lag time), and the time it takes to save the image and get ready to take another picture (recycles time.) Better (and higher-priced) cameras are speedier.

A startup time of a second or two is about as good as is currently possible, but some cameras take as much as ten seconds. Startup time can be influenced by the time it takes to charge the built-in flash, and can vary based on the charge in the batteries.

Lag time is the time between depressing the shutter release button, and the actual taking of the picture. A lag time of even a fraction of a second can mean missed pictures. For some cameras a proportion of this time is taken up by the camera focusing the lens and calculating exposure before taking the picture. It may be possible to reduce this time by depressing the shutter button halfway while framing your image, and before actually taking the picture. This makes the camera measure and pre-adjust focus so it is "ready" to take the picture when fully depressed.

Recycle time is the minimum time between pictures. This is the time it takes the camera to transfer the image to the memory card, recharge, and get ready for the next picture. Some cameras include a large amount of buffer memory within the camera for storing pictures temporarily before saving them to the card, which can reduce recycle time from 5 seconds or more, to a fraction of a second. However, there will still be a limit; after two or more pictures, you may have to wait while the buffer is emptied, which can cause missed shots. Note that while higher-resolution cameras usually have bigger buffers, they also have a lot more image information to save.

Viewfinders and LCDs

Most digital cameras use viewfinders and/or LCD displays to display the image to be captured. Viewfinders are optical systems that present a view very similar to what the lens actually sees. Viewfinders are usually more accurate the further the subject is from the camera; as you get very close to the object the accuracy will decrease dramatically.

By contrast, the LCD panels on most digital cameras let you see what the lens sees. This can be especially useful for close-up photography. LCDs also let you hold the camera away from your head while taking pictures from high or low angles. Unfortunately, LCDs are often difficult to see in bright sunlight. The SLRs also, let you see what is coming through the lens in the viewfinder; though at a price. When the picture is taken, the image is briefly obstructed.

Memory Cards

Most digital cameras use flash memory cards to store images. You then transfer the images to a computer, erase them from the card, and take more pictures. There are three major types of memory cards in use today; Compact Flash, SmartMedia and Memory Stick.

Unless you are already using a particular type of memory and have an investment in cards and readers, there's little reason to choose one over another in terms of performance or price. The one exception is that special high-performance memory cards are available at premium prices that will speed up the lag time between shots somewhat. These are generally only worthwhile if you have a high-end camera, and must take fast-paced shots.

Probably the most important point to make about memory cards is that nearly all cameras come with very small ones, often holding 20 or fewer pictures at highest resolution. Budget for enough memory to take at least 48 pics or so at your desired resolution and compression settings. Some camera that support CompactFlash, can also accept the IBM MicroDrive, an actual mini hard drive that can hold a full gigabyte of data, enough for a vacation's worth of pictures, even at high resolutions.

Battery Life and Flash Attachments

If you've used a digital camera before, you know how power-hungry they can be. Chances are, you've missed a lot of good shots because your battery went dead at a critical moment. The bad news is that the better the camera (in resolution, memory and features), typically the more power it requires. Large LCD screens are especially big memory hogs. The best defense here is to be prepared, and always have a second battery with you.
There have been notable improvements in battery design and performance; though this comes at a cost. Many cameras now use special custom rechargeable batteries that, while offering much longer times between recharging, cost more to buy if you want to have a second backup battery. If your camera uses a 'standard' AA size you can buy relatively inexpensive rechargeables as well as an AC adapter. If you do have a second battery, remember to keep it charged at all times!

Flash attachments can be used with some cameras, in addition to the built-in flash, which is often underpowered. Using a bounce flash on a hot shoe attachment (just like with a 35mm camera) eliminates annoying red-eye, which seems to happen even with the special red-eye reduction feature on many cameras. A more powerful flash can also illuminate more of the background, resulting in a more natural-looking shot with more image detail. Note that there are both hot-shoe and PC-sync connections available, and not all cameras feature both (or even one.) Also, many camera manufacturers recommend their own flash units with their cameras. While buying the same make of flash should ensure better communication between camera and flash unit, you may get good results with third-party units. If you're not sure, a trip to a camera store might be the safest way to check that your camera will communicate with the flash you want to buy.

Getting Pics Into Your Computer

Most cameras use USB cables to transfer pictures from camera to computer. This is a simple, hot-pluggable, process, once you install the USB driver. The latest cameras don't even require special download software, since their memory cards can be automatically read by the host operating system.

If you don't want to bother with plugging in your camera, or have multiple memory cards, another option is to buy a card reader or PC Card adapter. These cost anywhere from $25-$90, depending on features (some can read multiple card types).

The Bottom Line

We've covered the major digital camera features to look for. There are many other features in some cameras, such as automatic exposure settings for different lighting situations, manual exposure settings for serious photographers, and extras such as the ability to capture video sequences or audio along with pictures. Since technology is improving rapidly, we recommend buying close to the state of the art, if you can afford it. That way, you won't feel you need to replace the camera within a year or two. If not, decide what features are most important to you from the list above. As with most things in life, you get what you pay for in digital cameras.

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