Selecting a Digital Camera


Lots of different digital cameras are available, and understanding the differences among these cameras can make a big difference as you begin to shop.

The most important distinguishing feature in a digital camera is the maximum resolution that it can take. The maximum resolution also affects the price of the camera.

Caution 

Don't base your purchasing decision on a single feature such as resolution. A camera with a high resolution and a poor dynamic range may not be the best bet.

Resolution in megapixels

Camera resolutions are measured in the number of megapixels that a camera can shoot. This value is a combination of the number of horizontal and vertical pixels for the image. For example, a digital camera that can capture 2500 horizontal pixels by 1900 vertical pixels can save the image in a 5.0 megapixel camera.

The preferred resolution depends on what you plan to do with the images you capture. The greater the resolution, the clearer the subtle details are. If you plan on simply sending the pictures you take over the Internet to share with relatives, then a lower resolution camera may be sufficient, but if you are planning on printing out your images, then larger resolutions are a must.

Note 

Some digital cameras report the interpolated resolution, which is the resolution they can produce after calculating the pixels positioned in between the captured pixels. This value isn't a direct measurement relative to what the camera actually captures.

Dynamic range

Related to the camera's resolution is dynamic range, which is the number of discreet grayscale levels that can be captured between the brightest and darkest areas of the image. A digital camera's dynamic range is controlled by the camera's sensor. If a camera has a poor dynamic range, then the images it captures are easily over- or under-developed. If this happens, then the amount of pixels that you can capture doesn't really matter because all the image's details are washed out in the shadows.

One way to check the image's dynamic range is to look at the image's histogram, which is a graph that shows the available levels for the image. Some digital cameras show the image's histogram on its LCD screen.

Camera lenses

A camera is only as good as the lens it has. More expensive cameras have finer, higher quality lenses. Most low-end digital cameras include an embedded lens, but for professional photography, look for a digital camera that can change lenses.

Lenses are measured by their focal length, which is measured in millimeters. This value determines the range that the camera lens can zoom in on a scene. A 35 mm lens is common for most shots, wide angle lens would be in the 24 mm range, and telephoto lenses would be in the 105 to 200 mm range. Camera lenses are another major expense for digital cameras.

Many high-end digital cameras can switch between different lenses, but lower-end digital cameras can simulate these different lens settings using a zoom feature. Cameras with a 3X zoom can provide wide angle and telephoto shots of the scene without changing position.

Digital cameras deal with zooming in two ways. An optical zoom feature includes a feature that actually moves the lens closer or further from the scene. A digital zoom feature zooms the image using logic programmed by software. Some cameras combine these two features to increase the amount of zoom power that a camera has.

Tip 

Cameras with an optical zoom feature are more expensive, but offer a greater chance to zoom in on the scene than those cameras with only a digital zoom feature.

Flash memory

The images taken with a digital camera are saved on a flash memory card. Some cameras have built-in memory, but memory cards are more common. You can switch out memory cards to save more images without having to download all the images off a camera. Once the images from a flash memory card are downloaded to a computer, you can clear the memory card and capture new images.

Flash memory cards come in different sizes; the larger the memory card, the more digital images it can hold. You can also alter the quality settings on your camera to take images with a reduced resolution. More smaller-resolution images can fit on a single memory card. For example, a 1GB flash memory card can hold 200 images that are 5MB in size, but the same memory card can hold 500 images if the resolution setting is reduced to capture 2MB images.

A number of different flash memory card formats are available and they aren't interchangeable. Only one type of memory card works with each specific digital camera. The available flash memory card formats include the following:

  • Compact Flash

  • Smart Media

  • xD-Picture

  • Secure Digital

  • Sony Memory Stick

Image formats

Digital cameras can save captured images in several different formats including RAW, TIF, and JPEG. The RAW format saves the actual data for the image without any digital processing. Photoshop can import RAW image data. The TIFF format works well and saves the image data without any degradation, but the file sizes can be large. Cameras that save images using the JPEG format can fit more images on a single memory card, but JPEG is a lossy image format meaning that it throws away some of the image data in order to get the file sizes smaller.

Note 

Although the JPEG image format throws away some image data to compress the image's size, it is very picky in which pixels it throws away so the image quality is retained.

Camera settings

Film cameras typically include several settings that can drastically change the resulting picture. Many digital cameras automatically control these settings for you with their point and shoot feature, but for some cases, you want access to manually control these settings.

The aperture setting controls the amount of light let into the camera through an opening, or aperture, in the lens; the aperture setting control (or commonly called the f-stop value) defines the size of the lens opening. It can also affect where the camera is in focus. The shutter speed controls how quickly the aperture opens and closes. For action shots with very fast moving figures, you want to set the shutter speed to act very quickly in order to capture the motion.

You can adjust an exposure control setting depending on whether you're shooting images inside or outside. Low light conditions need a longer exposure to capture the image. You can use color balance controls to control the tint of the image towards red, green, or blue.

Other features

Other features to consider when looking into the various digital cameras include the following:

  • Size: Some digital cameras are very small and unobtrusive. Higher-end cameras typically are much larger.

  • Sturdiness: If you need a digital camera that is waterproof or sturdy enough to take a fall, then look into a camera that is more rugged.

  • Battery power: Most of the smaller digital cameras use a set of double AA batteries, but they can run out of power quickly. Many cameras run on Lithium batteries providing longer battery life. Purchasing a set of rechargeable batteries is a good investment if you're planning on taking a lot of pictures.

  • LCD screen: Many people like to share their pictures when they take them and a larger LCD screen on the back of the camera makes this easier to do.

  • Auto Focus: Most lower-end digital cameras include features that automatically focus on the objects in front of you, but on some cameras, this feature focuses on the wrong items.

  • Flash: For indoor shots a flash can provide the needed lighting, but a built-in flash can quickly drain battery power. If the flash is disabled, it doesn't drain battery power.




PC User's Bible
PC Users Bible
ISBN: 0470088974
EAN: 2147483647
Year: 2007
Pages: 372

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