Some Digital Camera basics you need to know before buying one
November 26th, 2007
- 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.
If you haven’t yet made your digital camera purchase—or if you are planning to upgrade - you’re in luck. The field has never been more crowded with excellent choices, and as I
mentioned earlier, technology advances keep making these cameras better each year.
Even though the camera field is evolving all the time, the basics really don’t change. The
next few sections cover the most important elements to consider when shopping for a camera.
1. Resolution of your camera
First and foremost, figure out how much resolution you need. This should be the first decision you make, because it determines what cameras you will be evaluating. Use this handy table to decide what megapixel range you need:
Megapixels Actual Print Size
Sub-megapixel (VGA) Onscreen only (Web, email)
1 megapixel 3 × 5-inch prints
2 megapixel 5 × 7-inch prints
3 megapixel 8 × 10-inch prints
6 megapixel 13 × 19-inch prints, prints from small crop areas of the original image
Remember that even if you choose a 6-megapixel camera, you can set it to capture lower resolution images—even a mere 640 × 480 pixels—making your camera quite versatile. Or you can capture a high-resolution image and reduce its size on the PC in an image-editing program. The higher the resolution, the fewer pictures you can
store at a given time, so there is a bit of a trade-off. If you buy a camera with too little resolution, though, you can’t ever add information to a picture, and trying to “blow it up” to print beyond its ideal size will generate a pixely, grainy mess.
2. Learning about Optics
It is a camera, after all—not a computer. Don’t forget to weigh the optics carefully. Your camera’s optics should be made of glass, not plastic, and multiple “elements” help keep everything in sharp focus through the camera’s entire zoom range.
Also consider what kind of pictures you want to take. A fairly wide-angle lens is good for
landscapes, indoor shots, and general-purpose photography. If you want to take portraits or wildlife shots, a longer reach is important. But take a look at the specs for a digital camera - what the heck is a 9.3mm lens? Is that wide angle? Who knows? That’s why most digital cameras also advertise their focal length in “35mm equivalents”—in other words, if this digital camera were a 35mm camera, its 9.3mm lens would give you the same picture as a 50mm camera, for instance.
Making sense of all this can be a pain. Worse, there’s no one formula you can use to convert digital camera focal lengths into 35mm equivalents. That’s because the focal length of a camera lens is based on the size of the film, which in the case of a digital camera is the CCD chip. CCDs vary in size, and there’s no industry-wide consensus on standardizing the size of the CCD in all cameras. So, your best bet is to check out the equivalency figures on the camera box or on the manufacturer’s Web site. I’ve also concocted a formula you can use in a pinch to convert digital camera focal lengths to their 35mm equivalents. Since CCD sizes vary, this is only an approximation. In the following formula, AFL is the actual focal length of the digital camera’s lens, usually a small number like 5mm or 10mm:
35mm equivalent focal length = AFL / .19
So if the camera has a 6.5mm lens, for instance, you can run it through this handy little
equation and determine that it will work like a 35mm lens.
3. Flash
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:
4. Transfer Mechanism
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.
Those were some bare basics you need to be aware of before buying a camera. I admit that those are not just the only points you need to know but they are after all some basics. If you have more points to share, please let us know.
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