SVS-Vistek exo174, Manual

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SVS-VISTEK
Feature description 23
5 Feature description
This chapter covers features of SVCam cameras. Not every feature might
be supported by your specific camera model. For information about the
features of your specific model, please refer to the specifications area with
your exact model.
5.1 Basics
5.1.1 Global shutter
The shutter is describing the functionality of exposing the light sensitive
pixels of the sensor to light for a limited time. With global shutter all pixels
are exposed to light at the same time for the same time.
All pixel will be exposed to light at the same starting point, and all pixel
light exposure will stop at the same time. Fast moving objects will be
captured without showing movement distortion, except motion blur if the
moving object is so fast that the same point of the object covers different
pixels at start and end while exposing.
Using flash with global shutter is straight forward: just make sure your
flash is on while shutter is open, thus all pixels are exposed to light the
same time. You might flash at any time within exposure time.
5.1.2 Rolling Shutter
Rolling shutter is a method of reading out a CMOS sensor, where the
whole scene is scanned line after line very rapidly. Despite the speed of
scanning one line after the other („rolling“) is very high, it is important to
note that the instant of imaging a single line will be different to the point
of time of the next line imaging. As this works out without any effect in the
final image with still sceneries, at moving objects you get geometric
distortions (see example of rotating propeller), showing fast moving
structures in an predictable, in the first moment yet surprising way.
As it takes some time to read out a whole sensor (and the whole sensor
has always to be read out!) you need to make sure that light conditions
are stable while reading the sensor. This restriction applies especially to
using PWM driven lights or flash lighting with rolling shutter. Unstable
light conditions will result in a horizontal line structured pattern noise.
Rolling shutter cameras in general are more sensitive in their light
response than global shutter ones.
propeller w/ rolling shutter artifacts