Digital Cameras: The Top Five Features

By - Megapixel.net Staff | Posted August 06, 2007

This article is intended as a synopsis of desirable features to consider when selecting a digital camera. We have purposefully left out some items: the ergonomic design of a camera; the type of viewfinder; the size and resolution of the LCD monitor; etc. Instead, we have tried to distill those things we believe to be the most important elements.


Resolution
As of this writing, and excluding special application cameras, digital cameras are available with sensors that cover a range from 640 x 480 (307,200 pixels) up to 14 megapixel (14 million pixels). For most people though, the current economic limit is 8 megapixels.

A word of caution when considering resolution: The true resolution of the sensor is what matters, meaning the number of pixels physically present on the sensor and not the resolution of the image. If the image the camera produces is bigger than the number of pixels on the sensor, for instance if the CCD is 3 megapixels but the image size is 6 megapixels, the image is interpolated.

Strictly speaking, the higher the resolution, the greater the detail a camera can capture, meaning that an 8 megapixel image will always have more detail than a 1 megapixel image. Likewise, larger resolution images result in more detailed prints, and if desired, larger prints.

But when the gap in resolution is not as large, such as is the case between 3.2 megapixels and 4 megapixels, other factors can tip the balance toward a camera with a lower resolution, and its photos may end up being more detailed than those of the higher resolution model. One of the factors that can impact the amount of detail a camera captures is compression.

Compression and Image Formats
One of most important things to look for when purchasing a camera is the type and variety of image file formats it offers. The vast majority of images captured with digital cameras are stored in JPEG format. JPEG uses a lossy compression algorithm that reduces the color hues of the image in order to reduce its file size. That lessens both the time it takes to save it and the space it takes up on the memory card.

The downside of the JPEG format is that if the compression applied to the image is too strong, the quality degrades visibly, and images become much less detailed than they should be. It is therefore critical to ensure that any camera offer a good selection of compression settings.

A camera should offer at least three image compression settings, and one of these should offer a limited compression, creating files that are no less than 1/4 to 1/6 the uncompressed file size. If possible, an uncompressed format should also be available (TIFF) and/or a RAW format that simply stores the image captured by the sensor "as-is".


Lens
Most compact digital cameras have an optical zoom lens — not to be confused with a digital zoom — and zoom lenses should meet some basic minimums.

A lens should have a fairly bright maximum aperture — f2 or f2.8 — and should correct for distortion: barrel distortion at the wide-angle end, pincushion distortion at the telephoto end and chromatic aberration.

If you're considering a long telephoto lens, the maximum aperture available at the telephoto end should be checked. Lenses that have relatively small apertures at the maximum telephoto position may require a lot of ambient light to avoid camera shake. Alternatively, it may be advisable to look to a camera that offers a stabilized lens. Additionally, very long telephoto lenses tend to produce better image contrast when they're built with LD (Low Dispersion) glass.

Shutter Speed Range and Noise Reduction
The shutter speed range of the camera should be checked. Cameras that have the combination of bright lenses and high shutter speed are better at stopping fast action. Similarly, cameras that are capable of long exposure times — at least 8 seconds — are able to capture photos at night. Ideally, the shutter speed range of the camera should extend to both fast and slow shutter speeds. Moreover, a camera able to capture long exposures should offer a noise reduction feature.


Shooting Modes
The availability of a good range of shooting modes is an important element of a camera. People who want point-and-shoot simplicity should also look for cameras that provide a variety of Scene modes. Scene modes automatically set a number of shooting parameters for specific types of image types. While not all of these modes are useful, a handful of basic scene modes can be very handy:

•Portrait
•Night Scene
•Landscape
•Sports
•Beach/Snow
•Sunset

For people who want the flexibility to experiment with the way the camera captures images, the more "hands-on" Aperture Priority, Shutter Priority and Manual modes should be available. Moreover, the ease of use of the modes — the way shutter speeds or apertures are adjusted — should be checked.

Burst (also called Sequential) shooting modes should also be part of the package. These modes are designed to capture a series of images quickly so as to overcome the shutter lag of the camera. While many cameras nowadays exhibit very little shutter lag, autofocus and metering still require a bit of time. Burst modes go a long to overcoming this by allowing the photographer to capture as the action unfolds. 

Other Important Features

Adjustable ISO: This means that the camera can be forced to a specific sensitivity. This provides control over noise and can be useful as a tool to expand or contract the shutter speeds available to the camera.

White Balance: Just about every camera nowadays offers a control over white balance, that makes it possible to set the white point for a specific color of light (cloudy, shade, tungsten, fluorescent, etc.) should the Auto mode not be able to produce accurate colors.

One setting however is not yet universally offered, a Custom or User-set white balance that allows setting the white balance for a particular light source that is not part of the camera's presets. Yet, that feature should also be considered a necessity.

Exposure Compensation: Exposure compensation serves to adjust or tweak how the metering evaluates the subject. Most cameras offer compensation currently, and some go further and even offer Flash compensation. A range of ± (plus or minus) 2 EV is common, usually adjustable over 1/3 EV increments but sometimes in 1/2EV increments.

While exposure compensation may seem a bit daunting, it is in fact a very simple system that serves to shift where the metering assumes the "perfect" exposure point to be, by moving it slightly toward a brighter or darker image. Exposure compensation is useful in a variety of situations where the conditions might cause the metering to misjudge the light.

Exposure compensation, and if possible its automated version, Auto bracketing, should also be considered absolutely necessary.

Adapted from megapixel.net.

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