Imperx Cheetah 3G-SDI User Manual page 62

Cheetah Pregius Camera User Manual | 3G-SDI Interface
Default limits
Gain Limits
Gain Minimum Limit
Gain Maximum Limit
Exposure Limits
Exposure Minimum
Limit
Exposure Maximum
Limit
Iris Limits
Iris Minimum Limit
Iris Maximum Limit
If AIC (for a P-Iris lens), AEC, and AGC modes are enabled together, the camera starts by
changing the iris position first. Depending on initial lighting conditions, the camera applies AIC,
AEC, and AGC algorithms according to either Case 1 or Case 2 shown below.
CASE 1
When the current image luminance is lower than the target image luminance, the camera
expands the iris opening allowing more light through the lens. When the iris is Fully Open, the
camera indicates the minimum iris limit (in steps) has been reached. (The iris is Fully Open when
the current iris position (in steps) is minimum.) The camera then increases the exposure until
the exposure reaches the maximum limit. The camera indicates the exposure maximum limit
has been reached and increases the gain until either the target image luminance is achieved, or
the maximum gain limit is reached.
The camera maintains these values until the lighting conditions change and starts by decreasing
the gain first to decrease the image luminosity. If the gain minimum limit is reached, the
cameras decreases the exposure until it reaches the minimum limit. The camera then indicates
the exposure minimum limit has been reached and closes the iris until either the target
luminosity is achieved, or the iris is Fully Closed (maximum iris limit is reached).
CASE 2
When the current image luminance is higher than the target image luminance, the camera
contracts the iris opening allowing less light through the lens. When the iris is Fully Closed
(maximum iris limit is reached), the camera indicates the maximum limit has been reached.
(The iris is Fully Closed when current P-Iris position (in steps) is maximum.) The camera then
April 14, 2021
Value Description
0 dB
48 dB
Varies Depends on camera model.
Varies Depends on current frame time.
0 steps The iris is Fully Open (max. aperture).
73 steps The iris is Fully Closed (min. aperture). The maximum limit varies
based on the lens model.
You may need to adjust the iris maximum limit if the maximum
number of steps of in the lens differs from 73 (73 is pre-set value
for the Kowa LM25JC5MM lens in default (factory)
configuration). Please refer to the documentation on your P-Iris
lens for this parameter or contact a lens distributor for more
information.
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