How to Choose a Digital Camera
posted: November, 24 2004
By Becky Waring
Holiday time always brings out the cameras! If you're still using a film camera, or have an older digital camera, it's time to check out the new offerings. The latest digicams are so good, in quality and features, and prices have come down so far, it's hard to go wrong. 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 and share your images via email, Web, print and photo CD/DVD with fun software like Roxio's PhotoSuite 7 (sold separately and as part of the Easy Media Creator 7 package).
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, for yourself or a gift, and the key features to look for.
How much do you want to spend?
Before looking at specific features, decide on the general price range that's right for you:
1) Point-and-Shoot: These easy-to-use digital cameras are excellent for families (and kids!), vacations, and general use, and range from $100 to $500. These cameras are typically in the 3.2-to-5 megapixel range (more on what a megapixel is, below!), and often quite compact in size. Fewer megapixels can be had, but cameras are so cheap these days that there's no reason to compromise any more.
2) Mid-Range: Moving up a notch, we find cameras with more resolution (typically 5-to-8 megapixels, which lets you create great-looking enlargements) and pro-am features such as manual controls, powerful zoom lenses, and flash hot shoes, in the $400 to $800 range. These are the right cameras for people who really care about their images, but can't afford a digital SLR.
3) Digital SLRs: At the top end of the spectrum, digital SLR cameras with interchangeable lenses just like their film counterparts are in the $1,000-$2,000 price range and should continue to decrease in price. These cameras offer true film-like flexibility for the serious hobbyist, and resolutions from 6 to 8 megapixels. If you don't need interchangeable lenses, cameras in the $800 range offer similar resolution, features, and image quality. This is the gift for that very special someone, perhaps even yourself!
How many megapixels is enough?
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-to-6 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 need to get into the 8-to-12MP range.
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.
At 2.1 megapixels you can print 4x6 photos with results comparable to film. With a little more detail, 3MP will let you edit these photos and make computer manipulation more convenient. At 4 megapixels, there is usually enough detail for 8x10 prints. We'll tell you how to calculate how many pixels you need for your printer below.
If print quality is your primary concern, decide on the maximum print size you expect to use (such as 5x7 or 8x10), and note the true 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.
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 (ppi).
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 200ppi, you need a camera capable of shooting at least 1,600-by-2,000 pixels, or about 3.2 megapixels. Again, we recommend rounding up (in this case to 4 megapixels), so you can crop photos where needed.
Another important point is that 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, so use the least compression possible for the best quality. Of course, the more compression used, the more images you can capture before the memory card is filled.
Should you use fixed or interchangeable lenses?
Producing good quality optics for digital cameras can be a challenge. The CCD imagers used in these cameras have a much smaller capture area than a typical 35mm film frame, so lenses must be of very good quality to produce a good image. But choices in lenses continue to increase, and you can get add-on lenses for some cameras, such as wide-angle and close-up attachments. For the most flexibility (and highest quality) you will want to look at the more-expensive digital SLR cameras with interchangeable lenses.
When comparing lenses, we are most interested in the field of view of a lens (how wide or narrow it is). 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, such as 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. So look for an image stabilization system in a long lens camera. Also, many low-to-midrange zoom cameras suffer from problems with barrel distortion at the wide angle end (the image sides appear to be slightly bowed.) Check reviews for the cameras you are interested in.
Finally, it's important to distinguish between optical and digital zoom. With optical zoom, lenses move to scale the image, 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 also 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.
How does camera speed affect performance?
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 (recycle 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, 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 a few 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.
What's the difference between 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 an image 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 image sensor sees, or exactly what your final picture will look like. 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, and use a lot of power. Whenever possible, use the viewfinder to take your pictures to prolong battery life.
How much memory is enough?
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, Compact Flash, SmartMedia and Memory Stick, and a couple lesser ones.
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. We highly recommend getting a premium memory card. They only add a few dollars to your total, and can greatly improve the user experience with most digital cameras.
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 64 pics or so at your desired resolution and compression settings. If you are going on vacation without your computer to download images to, you'll want a card big enough to hold all your photos at once, perhaps 512MB or 1GB.
Which battery and flash options should you buy?
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. Sometimes things like the power zoom can fail when the battery is weak, as well. 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.
Many cameras use special custom rechargeable batteries that, while offering longer times between recharging, cost more to buy if you want to have a 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 (as with a 35mm camera) eliminates annoying red-eye, which seems to happen even with the special red-eye reduction button found on many consumer-level cameras. A powerful flash can also illuminate more of the background, resulting in a natural-looking shot with more image detail. 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 flash attachments. 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.
How do you get the pictures 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 (most can handle 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 the budget is tight, decide what features are most important to you from the list above. As with most things, you generally get what you pay for in a digital camera.