IDEC DATAVS1 Series - Manual (Page 82)

Instruction Manual SVS1 Series
77
14.9. Exposure
Exposure time determines how long the image acquisition device must remain exposed to light.
Image quality depends on this parameter, that is determined based on:
• Lens aperture;
• Exposure.
The term Lens aperture denotes the ratio of lens length to lens width. A longer lens (where light travels
a longer distance) will have a higher ratio and will provide less strength. Conversely, a shorter lens
features a lower ratio (fast lens).
The term exposure time is also known as "shutter opening time" and is directly proportional to the
quantity of light hitting the sensor: the greater the shutter opening time, the greater the quantity of
light, hence the brighter the acquired image.
A fast lens allows for shorter exposure time.
This is because exposure is a combination of aperture and exposure time: as these are inversely
proportional, doubling aperture allows for halved exposure time.
This determines correct exposure, which is the right quantity of light needed for details to be visible
both in the dark and bright areas of the image.
Underexposure will result in crushed blacks, i.e. loss of detail.
Overexposure will produce blown-out areas (bright, pale and flat).