Monday, March 26, 2007
Choosing The Right Digital Camera For You
How to narrow the multitude of options? Consider your photography habits and the features you really need
Manual Capability. If you think you might want to control things like exposure, focus, shutter speed and aperture yourself, make sure your camera offers both easy manual and auto control of these features. How easy/difficult is it to focus the camera manually? I find focusing by rotating a focusing ring on the lens barrel much easier and more accurate than focusing via buttons on the camera body; you may prefer the more common button approach.
Focal Length. Lenses built into compact digital cameras actually have very short focal lengths: For example, the 10x zoom built into the popular Nikon Coolpix S10 is 6.3-63mm. The focal lengths are short because the image sensors in these cameras are very small compared to a full 35mm film frame. Because most photographers are familiar with the views provided by lenses on film cameras, digital-camera specs also give 35mm-equivalent focal lengths, indicating what film-camera focal lengths the digital camera's lens frames like. (For our example, the Coolpix S10, it's 38-380mm.)
Zoom Range. Compact digital cameras come in several varieties, lens-wise: fixed focal length (usually with a semi-wide-angle lens built-in), normal zoom (2x-5x or thereabouts) and wide-range zoom (at least 19 models with built-in zoom lenses of 10x or greater are available as of this writing).
Consider the widest focal length and the longest focal length provided. Most zoom compacts start at 35mm-equivalent focal lengths of 38mm or so-sort of wide-angle, but not very. If you like to do wide-angle work, find a camera that offers a wide-angle lens (true wide-angles are available for all of the D-SLRs). Accessory wide-angle adapters are available for many compact digital cameras. D-SLRs, of course, accept a wide range of interchangeable lenses. Check out what's available for the camera models you're considering, and make sure the lenses you'll need are available for those bodies.
Lens Speed. Lens speed refers to the size of the lens' maximum aperture. The larger the maximum aperture (i.e., the "faster" the lens), the more light it transmits. This gives you faster shutter speeds (or allows you to use lower ISO settings for better image quality) in any given light level.
Most built-in and lower-priced interchangeable zoom lenses are of the variable-aperture variety: The lens has a larger maximum aperture at its shortest focal length and a smaller maximum aperture at its longest focal length. For example, the popular Canon G7 camera has a 7.4-44mm ƒ/2.8-4.8 zoom, meaning its maximum aperture at the 7.4mm setting is ƒ/2.8 and at 44mm is ƒ/4.8.
Because of their very short actual focal lengths, lenses built into compact digital cameras tend to be faster than lenses built into compact film cameras, especially at the longer end of the zoom range. But keep in mind that the lens gets slower, requiring a slower shutter speed in any given light level, as you zoom to longer focal lengths, and camera shake becomes more evident as focal length increases.
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