Pyramid Imaging EXO Series, Manual

Page: 49 / 135

SVS-VISTEK
Feature-Set 49
Rolling Shutter Limitations
Due to the principles of rolling shutter, some standard features of SVS-
Vistek cameras are not applicable. This relates to following
Exposure Control with Rolling Shutter
In the graphics above, it is easy to see that external exposure control does
not make sense with rolling shutter. Exposure delay and Overlapping
Exposure as well is impossible with rolling shutter.
ROI with Rolling shutter
With Rolling shutter the whole sensor has to be read out – always. That
means applying ROI will reduce the amount of final data being
transmitted out of the camera (and the framerate might rise, due to the
limited bandwidth of the interface). Nonetheless, the maximum achievable
framerate with applied ROI will be the maximum framerate of the sensor
reading the full sensor area (internal full sensor speed), please refer to the
relating sensor specs.
Calculate Framerates
According to the calculation as below, the requested times for scanning
through all lines of the sensor will affect maximum framerate calculation
as well.
In this example, the camera is an exo183 with 3672 lines and 54 dummy
lines. Each line takes 22.2 ms readout time (depending on CameraLink
tap configuration). The camera does have about 300µs exposure time
delay at worst case.
Framerate calculation with exo183CCL with rolling shutter
lines 3672
dummy lines + 54
total lines 3726
readout time 1x3_1Y 22,2 µs * 3726 = 82717,2 µs
exp delay + 300 µs
frame readout time 83017,2 µs
This is minimum time for camera readout with 0s exposure time.
Exposure time has to be added:
frame readout time 83017,2 µs
exposure time 2500 µs
total frame time 85517,2 µs
maximum sensor acquisition time 1/ frame time 11,6936 fps
note: readout time 1x2_1Y = 32,63 µs