Grasping the Technical Details 9
Choosing a Shooting Format
Some cameras offer you a choice between two image formats: JPEG and RAW.
JPEG (which stands for Joint Photographic Experts Group) is a format that
reduces the amount of information that makes up a picture. It throws away
information that the eye ordinarily can’t discern, and uses sophisticated meth-
ods to compress the information that does remain so that you can fit more
images into the camera’s storage.
RAW pictures, on the other hand, retain nearly all of the information that
came into the camera when you took them. As a result, RAW images take up
considerably more storage space than their JPEG-compressed equivalents:
often as much as 10 to 15 times as much storage. The advantage of RAW pic-
tures is that they offer you much finer control when you modify them with
image editing tools, such as the ones that iPhoto provides.
For casual photography, or to conserve storage space on your camera or your
Mac, you can use the JPEG format with no qualms. Many digital cameras, in
fact, offer only the JPEG format.
However, if you plan to make professional use of your pictures, or if you want
to have the maximum amount of control when you fine-tune your images, you
should consider the RAW format. Just make sure you have plenty of storage
space available.
Capturing GPS Data
Courtesy of the U.S. Department of Defense, dozens of satellites circle Earth as
part of the Global Positioning System, commonly known as GPS. These satellites
broadcast microwave signals that terrestrial devices can use to pinpoint their loca-
tions. The system is used by aircraft, automobile navigation systems, and even digi-
tal cameras, such as the one included in the iPhone 3G.
If you have a camera that includes GPS capability, the camera can obtain a
precise record of where a picture is taken, and it can store that location infor-
mation in the picture itself.
Usually, because the GPS receiver in a camera can use up a significant amount
of battery power, the GPS receiver can be turned on or off at your discretion.