Digital Camera Master

In digital photography, not only are you faced with the traditional trade-offs between shutter speed and aperture size, but you also must choose from among a number of settings that determine file size (which ultimately is a trade-off between files that take less space to store and less computer processor cycles to edit) and image-quality. The five major factors determining image file size are image resolution, image format, compression level, ISO setting, and the subject. You can control the first four of those five factors with user-selectable settings that allow you to optimize image file size with image-quality to meet your needs.

Almost all digital cameras offer user-changeable settings for image resolution. For example, the Canon PowerShot G2 has a maximum image size of 2,272 × 1,704 pixels. It also has image resolution settings of 1,600 × 1,200, 1,024 × 768, and 640 × 480.

What image resolution setting should you use? The answer depends entirely on what you plan to do with the image, how much incamera storage and computer storage space you have, and how important image-quality is to you. Image resolution is costly in terms of file size—the higher the resolution, the more space required to store a single digital photo, and the more computer processor cycles required to edit it.

If you want to be able to make the best and largest print possible, you will always want to use the highest image resolution setting your camera offers. If you have a 4- or 5-megapixel or larger camera, you may not always want to use the highest image resolution setting if you intend to only print 4″ × 6″ photos.

Choosing a lower image resolution allows you to get more images on your digital photo storage media, and these smaller image files require less computing power than larger images would. Additionally, smaller images require less storage and backup space on your hard drive or removable media. So, when possible, a lower resolution setting is a good choice. To learn more about the different resolutions and their resulting file sizes, and the number of images that you can store on a specific digital photo storage media card, check the documentation that came with your camera—vendors usually provide a table with this information.

One reason against using any image resolution other than the maximum size is that a larger image may allow you to crop an image to show exactly what you want.

Image resolution settings are usually changed via a menu, or a button that changes the setting that is shown on an LCD.

WARNING
After you learn how to change the image resolution setting, be careful! I once drove with a photographer friend for several hours to get to a remote place where we had heard there were rare butterflies. After several hours of shooting these rare butterflies in the hot sun, my friend noticed that he had far more room on his digital photo storage media than he should have had considering the number of photos that he had already taken. A quick look at the image resolution setting showed why. A day earlier he changed the setting to shoot images for a Web page and he had forgotten to change the settings to the maximum image resolution! All of his wonderful shots of these rare butterflies were unprintable because he had been shooting 1,536 × 1,024 pixel images — not nearly enough f or the 8″ × 10″ prints that he wanted to make!