Instruction manual

Marlin Technical ManualV.2.7.0

137

Controlling image capture

Shutter modes The cameras support the SHUTTER_MODES specified in IIDC V1.3. For all models

this shutter is a global shutter; meaning that all pixels are exposed to the light

at the same moment and for the same time span.

Continuous mode In continuous modes the shutter is opened shortly before the vertical reset hap-

pens, thus acting in a frame-synchronous way.

External trigger Combined with an external trigger, it becomes asynchronous in the sense that it

occurs whenever the external trigger occurs. Individual images are recorded

when an external trigger impulse is present. This ensures that even fast moving

objects can be grabbed with no image lag and with minimal image blur.

Camera I/O The external trigger is fed as a TTL signal through Pin 4 of the camera I/O con-

nector.

CMOS sensors For CMOS sensors, a global shutter is not common. Normally a rolling curtain

shutter is used to shorten the exposure or integration time. The curtain's width

defines the integration time and the curtain sweeps with the frame readout time

over the image. Although this is appropriate for still images, image distortion

will be created with moving objects, because the upper image part is scanned

earlier than the lower image part. For this reason the Marlin F-131 features a non

pipelined global shutter only. A side effect of this type of global shutter is that

the integration or shutter time is added to the readout time, thus affecting the

frame rates to be achieved.

Trigger modi

Marlin cameras support IIDC conforming Trigger_Mode_0 and Trigger_Mode_1

and special Trigger_Mode_15 (bulk trigger).

Trigger Mode also known as Description

Trigger_Mode_0 Edge mode Sets the shutter time according to the value set in

the shutter (or extended shutter) register

Trigger_Mode_1 Level mode Sets the shutter time according to the active low

time of the pulse applied (or active high time in the

case of an inverting input)

Trigger_Mode_15 Programmable mode Is a bulk trigger, combining one external trigger

event with continuous or one-shot or multi-shot

internal trigger

Table 62: Trigger modi