Controlling image capture
MARLIN Technical Manual
V2.4.0
126
The following screenshot shows an example of broadcast commands sent with
the Firedemo example of FirePackage (version 1V51 or newer):
•
Line 1 shows the broadcast command, which stops all cameras con-
nected to the same IEEE 1394 bus. It is generated by holding the
Shift
key down while clicking on
Write
.
•
Line 2 generates a
broadcast one-shot
in the same way, which forces all
connected cameras to simultaneously grab one image.
Jitter at start of exposure
The following chapter discusses the latency time which exists for all CCD
models when either a hardware or software trigger is generated, until the
actual image exposure starts.
Owing to the well-known fact that an
Interline Transfer CCD
sensor has both
a light sensitive area and a separate storage area, it is common to interleave
image exposure of a new frame and output that of the previous one. It makes
continuous image flow possible, even with an external trigger.
CMOS
This is different to the way the
CMOS sensor of the Marlin F-131
works: the
image sensitive area is also the storage area, which means that it cannot be
used for the integration of the new frame until it has been read out.
Continuous image flow is thus only possible with the so-called rolling shut-
ter.
Asynchronous image acquisition only makes sense with the global shutter;
leading to a non-interleaving exposure - readout - exposure sequence. For
every exposure cycle the sensor is completely reset so that the camera needs
to be idle.
Figure 68: Broadcast one-shot