Camera Controls
These adjust image acquisition parameters such as exposure, pixel binning, cropping and
lens control. Table 3.2 shows the full set of available ‘Camera’ controls.
Control Name
Min
Max
Step
Default
Auto Exposure
0
3
1
3
Exposure Time, Absolute
50
10000
1
166
Exposure, Dynamic Framerate
0
1
1
1
Pan, Absolute
-57600
57600
3600
0
Tilt, Absolute
-43200
43200
3600
0
Zoom, Absolute
0
3
1
0
Focus, Automatic Continuous
0
1
1
1
Focus, Absolute
0
1022
1
68
Table 3.2 ‘Camera Controls’ for the AF51 Camera. The minimum possible value, maximum possible value
and default setting value are shown as well as the minimum step change that is permitted.
Notes:
The ‘
Auto Exposure
’ can be set to 2 values: 1 (corresponding to ‘
Manual Mode
’) and 3
(corresponding to ‘
Aperture Priority Mode
’ which is the AEC). Although the camera
firmware reports that a range of 0-3 is possible the values 0 and 2 cannot be set in the
AF51 (they are redundant for this model).
The AF51 does not have a separate ‘gain’ control. The exposure setting (whether manual
or automatic) actually sets both the gain and exposure simultaneously. The relative
contribution of gain and exposure is calculated by means of an on-chip algorithm that is
designed to maximise the SNR for any given lighting condition. See below for details.
Manual mode provides a constant, fixed, gain value and exposure time. This is set via the
‘
Exposure Time, Absolute
’ control value. This value can only be set or changed while
the camera is in manual exposure mode (i.e. ‘Auto exposure’ is set to 1). Practical
experience shows that the gain component in manual mode tends to be lower (so there is
less noise) and the exposure component higher (slower frame rate) compared to an
equivalent low light level sensitivity achieved with the AEC. However the AEC can achieve
greater sensitivity overall than any manual setting (see below).
The ‘
Aperture Priority Mode
’ corresponds to automatic exposure (the characteristics of
which can be modified via the ‘Backlight Compensation’ setting as described in the
previous section) .
OptArc AF51 Camera Page 28 of 99 User Guide v1.02