155Reference10Basic TerminologyApertureThe aperture value (f/number) indicates the size of theaperture opening in the lens. It is equal to the focal lengthdevided by the aperture diameter. It adjusts the amount oflight striking the CMOS sensor. The aperture value isdisplayed on the camera’s top LCD panel and in theviewfinder. It can range anywhere from 1.0 to 91,depending on the lens attached to the camera.Shutter speedThe shutter speed is the length of time the camera’s shutter opens to expose the CMOSsensor to the light coming through the lens. It adjusts the amount of light striking the CMOSsensor.FormatWhen you format a CF card, it prepares the card to store data in it. It also erases any datastored on the card. Before formatting a CF card, be sure it has no valuable data.File namesA file name is assigned automatically to each imageyou capture. The file name consists of a unique, four-character camera code preset at the factory and a filenumber assigned automatically. The camera codecannot be changed. The file number is assignedautomatically according to the numbering method youselected (→p.56).The extension will be “JPG” for JPEG images or “TIF” for RAW images. For sound files, theextension will be “WAV.”FirmwareThis is software containing various camera control instructions. The EOS-1Ds uses thefirmware for shooting and image processing. Although the firmware is preinstalled in thecamera, you can later install the latest version of the firmware when it becomes available.5F9Z0001.JPGExtensionFile numberCamera code(Example)
