Controlling image capture
OSCAR Technical Manual
V2.4.0
111
Exposure time (shutter) and offset
The exposure (shutter) time for continuous mode and Trigger_Mode_0 is
based on the following formula:
Shutter register value x time base + offset
The register value is the value set in the corresponding IIDC register
(SHUTTER [81Ch]). This number is in the range between 1 and 4095.
The shutter register value is multiplied by the time base register value (see
Table 85: Advanced register: Time base
on page 184). The default value here
is set to 20 µs.
A camera-specific offset is also added to this value. It is different for the
camera models:
Exposure time offset
Example: Oscar F-510C
100 x 20 µs +
74
µs = 2074 µs exposure time
The minimum adjustable exposure time set by register is
20
µs.
The real minimum exposure time of an Oscar F-510C is then
20
µs +
74
µs = 94 µs in frame readout mode.
Camera model
Offset interlaced
Offset progressive
Oscar F-320C
46
µs
57
µs
Oscar F-510C
74
µs
83
µs
Oscar F-810C
98
µs
98
µs
Table 36: Camera-specific offset
Camera
Register value
Timebase
Oscar F-510C in interlaced (frame
readout) mode
100
20 µs
Table 37: Register value and time base for Oscar F-510C
Note
L
Generally all Oscar cameras enable certain image settings to
be modified on the fly, e.g. gain and shutter can be changed
by the host computer by writing into the gain and shutter
registers even during camera operation. An uncertainty of
one or two images remains, as the host is unaware of (espe-
cially with external trigger) when the next image will arrive.