Learn the secrets of getting great, clear photographs no matter what the situation. This guide teaches you the fundamentals of digital photography, and reveals the tricks pro photographers use to get great images of people, objects, live action, and much more.
Basic camera controls
Your first step as a photographer should be to evaluate your subject, the setting, and your camera's capabilities. You then can figure out how to bring those components together to create a tasty visual treat.
This section provides an overview of all the major digital camera controls, explaining the creative impact of each option and offers recommendations about which settings to use in various shooting scenarios. As you read, you may want to have your camera manual handy so that you can confirm whether your camera offers a particular option, and if so, how you activate that feature.
Exposure modes | White balance | Digital zoom
Image resolution
The resolution control determines the number of pixels that your camera uses to produce a picture. Your camera likely offers three or more resolution settings, each delivering a different pixel count. You may see your options presented in terms of pixel dimensions, such as 2288×1712, with the horizontal pixel count listed first, followed by the number of vertical pixels. However, some manufacturers refer to the total number of pixels when labelling resolution options, using the term megapixel to mean one million pixels. For example, if you multiply 2288×1712 pixels, you get roughly 3.9 million pixels, or 3.9 megapixels which the folks in the camera marketing department round up to 4 megapixels).
Creative impact
If you're an experienced film photographer, you know that the larger the film negative, the more you can enlarge the photo without losing sharpness and detail. You can make a similar connection between pixel count and print size. The more pixels you capture, the larger you can print your photo without a noticeable loss of quality.
At snapshot size, the 3-megapixel tulip (left)
doesn't look much different from the 1-megapixel version (right).
When the print size is doubled, the 3-megapixel image (left)
offers significantly higher quality than the 1-megapixel photo (right).
Compression
Compression is a bit of software manipulation done to reduce the file size of a digital image. When you record an image in the standard digital camera file format -- JPEG -- the photo undergoes lossy compression, which means that some image data is eliminated in the name of smaller files. You can significantly lower file size by applying lossy compression. Some cameras also enable you to store pictures in the TIFF format, which applies either no compression or lossless compression. Lossless compression tosses only redundant data and therefore doesn't shrink file size much.
On most cameras, the compression option is labelled Picture Quality or something similar, and the available settings have vague names, such as High, Fine, Normal, and Basic. The type and amount of compression that these settings apply vary from camera to camera, so look in your manual for details about your model. Compression enables you to fit more pictures into your available camera memory. Be aware, however, that the more compression you apply, the more you sacrifice image quality.
As is the case with a low-resolution image, a highly compressed image may appear only slightly degraded if printed at a small size and on uncoated paper stock. But if you enlarge the images or print them on glossy, high-grade stock, the impact of too much compression can become noticeable.
Manual exposure controls
When you take a picture, three camera components affect exposure:
- Aperture: The aperture is an iris in the lens that can be adjusted in size to control how much light enters through the lens. Aperture size is represented by f-numbers and written with the letter f followed by a slash and the f-number -- for example, f/2.8 The higher the f-number, the smaller the aperture size. The aperture settings themselves are referred to as f-stops.
- Shutter speed: The shutter is like a window shade behind the camera lens. When you take a picture, the shutter opens briefly to allow light to enter through the lens and strike the camera's image sensor. Shutter speed refers to how long the shutter remains open. The slower the shutter speed, the more light the sensor soaks up.
- ISO rating: ISO ratings are used to indicate the light sensitivity of the image sensor. The higher the ISO number, the greater the light sensitivity, and the less light is required to expose the image.
Exposure modes
Digital cameras, like point-and-shoot film cameras and some film single-lens reflex (SLR) cameras, offer programmed autoexposure -- AE for short. In this mode, the camera automatically chooses the proper combination of aperture (f-stop) and shutter speed needed to produce a good exposure. In addition to programmed AE, advanced cameras typically provide two variations on the theme:
Tip: When you use any autoexposure camera, you must press the shutter button in a certain way for the exposure mechanism to work properly. After framing the shot, press the shutter button halfway down and wait for the camera to signal you that it's analysed the scene -- usually, by sounding a beep or displaying a light near the viewfinder. Then press the button the rest of the way down to capture the image.
- Aperture-priority AE: Chooses the shutter speed automatically after you set the aperture.
- Shutter-priority AE: Sets the aperture automatically based on your selected shutter speed. Your camera may also offer a manual exposure setting that gives you complete control over both aperture and shutter speed.
Just as a movie director uses lighting to set the mood of a scene, you can use your camera's exposure controls to convey a certain feeling in the image. You can purposely underexpose an image to give the subject an air of mystery, for example. Beyond the obvious balance of light and dark in a photograph, however, you can alter other aspects of an image by taking control of aperture and shutter speed.
For example, you can adjust depth of field, or the range of the picture that's in sharp focus, by changing the aperture. The larger the aperture, the smaller the depth of field. Depth-of-field shifts get more noticeable as you zoom in or bring the camera closer to the subject.
WA large aperture produces shorter depth of field (left);
a small aperture brings a greater area into sharp focus (right).
White balance
White balance is purely a digital animal when it comes to still photography, but this control may be familiar to you if you're experienced with video cameras. As with a video camera, the white balance control addresses the fact that different light sources -- daylight, fluorescent light, incandescent bulbs, and so on -- have different colour temperatures. (Colour temperature is a measure of the hue emitted by a particular light source.) White balance enables the camera to compensate for any colour cast that may be created by the light source.
Digital zoom
Digital zoom is nothing like having a true, optical zoom lens. Digital zoom simply enlarges the existing image and crops away the outer edges, just as if you had taken the same steps in a photo editor. The quality of the resulting picture is reduced because you have fewer pixels in your "zoomed" image. So why do manufacturers offer this feature? Simple. Most people don't understand the difference between digital and optical zoom, and they think they're getting something important when they see "digital zoom" on the camera box. Or they may see only the part of the camera ad that claims "28X total zoom!" and completely miss the fine print, which reveals that the model in fact offers an optical zoom factor of only 3X, with the rest of that 28-times magnification being produced by digital trickery. Camera salespeople will sometimes say that a cheaper camera with only a digital zoom is better than a more expensive model with an optical zoom -- because the magnification number (that X factor) is higher on the model with the digital zoom. This is simply not true.
Content adapted from Shoot Like a Pro!: Digital Photography Techniques, McGraw-Hill Publishing, and used with permission: CNET Networks © 2007, and McGraw-Hill © 2007.
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