SIGMA SD9 - Manual (Page 105)

EXPLANATION OF TERMS
AE
Auto Exposure; by using a built-in exposure meter, camera determines the correct
exposure value, which is combinations of shutter speed and/or aperture value.
AE Lock
The camera will fix and memorize the exposure value with AE lock. For example, if a
photographic subject is placed in the center and exposure value of the composition is
fixed, the brightness of the background will not influence the exposure, even if the
composition changes and the subject is moved from the center of a screen. (AE lock
button must be used).
AF
Auto Focus; by using a built-in sensor, camera adjusts the focusing automatically.
AF Lock
In AF shooting mode, you can lock the focus on the main subject. For instance,
compose the desired subject in the center of the viewfinder. With the focus fixed at
the same setting, you can re-compose the picture with the subject off-center and take
shots. (Please press the shutter button “Half-way” to use this feature with Sigma
SD9).
Aperture
The lens opening of the iris diaphragm inside the lens. The amount of light, which
strikes the image sensor, is adjusted by the iris diaphragm. The f-number (Focal
Length/Diameter of the Aperture Opening) describes the size of this opening, the size
of the hole can be made larger or smaller. Large aperture (low f-number) gives bright
results and, small aperture (high f-number) gives darker results.
Auto Power-Off
For saving the battery power, the SD9 camera can automatically turn itself off, if you
do not operate it.
CMOS
Complementary Metal Oxide Semiconductor (CMOS) can perform signal amplication
on a per-pixel basis. Significant current flows only during the switching operation.
Therefore a CMOS image sensor can scan data rapidly, sustain high-speed operation
and consume less energy. Recent technological and production improvements in
digital imaging systems are making CMOS more and more competitive in terms of
image quality and cost.
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