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Appendix
EV (Exposure Value)
An EV is a number that denotes exposure. EV=1 when the aperture setting is F1 and the
shutter speed is 1 second. Each time the exposure then halves, the EV number increases
by 1 (EV=2, EV=3...).
Conversely, when the exposure is double the EV=1 level, the EV becomes -1. When the
exposure is doubled again, EV=-2, and so on.
In general parlance, when we “change the exposure by 1 step” we are in fact referring to
this EV.
Exposure
This refers to the light of the image projected through the lens striking the camera’s CCD or
film for the optimum amount of time only. Generally speaking, exposure refers to the
combination of shutter speed and aperture setting that will give the correct image.
Flash
This is a device that produces a bright flash of light by releasing an internally stored high-
voltage current. Flash units use relatively large amounts of power and tend to deplete the
camera battery if used frequently.
Focal length
This is the distance from the center of the lens (secondary focal point) to the plane onto
which the image is projected (focal plane) when the image of a subject at an infinite distance
from the camera is clearly focused. The focal length of a lens relates to its magnification,
with longer focal lengths giving more enlarged images of distant objects.
Focus
This term refers to the focal point of a lens, but is more broadly used to refer to the condition
whereby the subject of a photograph is seen most clearly. When the focusing is correct and
the subject is clearly visible, the shot is said to be “in focus”. When this is not the case, the
shot is “out of focus”.
Format
The initialization of a memory card.
Infinity
Once the subject of a photograph is further than a set distance away from the camera lens,
moving still further away requires no adjustment to the focus. The distance at which the
subject is so far away that no change in the focus occurs is referred to as “infinity”.
Initialization (formatting)
This is a process that organizes the internal structure of a memory card so that data can be
recorded on the card. Initialization erases all the existing files on a memory card.
ISO (sensitivity)
This is a number that indicates the sensitivity of film to light, with higher values indicating
greater sensitivity. This is generally expressed as “ISO 100”, etc. Film with higher ISO
sensitivity is more sensitive to light and can be used to take pictures in low-light conditions.
Even in digital cameras, which do not use film, sensitivity is still expressed in terms of ISO
numbers.
JPEG (Joint Photographic Experts Group)
This is a file format used for compressing and saving color images. The compression ratio is
variable, with higher compression ratios giving smaller image file sizes but poorer image
quality.
