ACTi I51 User Manual download pdf (Page 75)

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Firmware User’s Manual V6.08.30

the shutter speed within the allowed range (set by user under Slowest Auto Shutter Speed) and

increase the signal gain.

Slowest Auto Shutter Speed is the user defined threshold for slowest allowed speed of auto

shutter. For example, if by default the shutter speed would vary between 1/5s ~ 1/2000s

depending on the lighting conditions, then setting the Slowest Auto Shutter Speed to 1/30s would

narrow down the auto shutter range to work between 1/30s ~ 1/2000s. The purpose of allowing

user to define the threshold for slowest speed is to avoid motion blur caused by too slow shutter

at night.

It is also important to know that very high shutter speed is not recommended for indoor solutions

with artificial light that flashes with certain frequency, as it may produce flickering effect,

regardless of Exposure mode.

In extreme low light conditions, the shutter speed is slown down to get more light into one image,

but not slower than the user defined threshold.

If the exposure time extends beyond the interval between frames (too slow shutter), (i.e. 1/30

second), then the frame rate will be automatically reduced. Longer time in this value gives

clearer images at night for slow moving objects, but more motion blur for fast moving

objects.

White balance refers to the capability of the camera to understand what “true white color is”.

When the camera knows the true white color, then the rest of the colors will be accurate, too.

While human eye can easily adapt to different lighting sources (even mixed sources, such as sun

light through the window and indoor lights turned on at the same time), the camera has to

understand what is the dominant light source in given scene and what is the “white color” of such

light source.

By default the camera is in auto white balance mode and attempts to recognize the light source

and its color spectrum automatically and adjusts the image accordingly. This function works

continuously in the background. It is re-evaluated for each frame, to make sure if there is any

change in dominant light source (e.g. the user closes the curtains to block the sun light and turns

on the indoor lights).

In most cases the auto white balance works perfectly and the user does not have to adjust

anything! In some rare installation cases, especially when there are no white color objects in the

field of view, and the light sources are mixed, the camera may have difficulty to identify the true

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ACTi I51 User Manual Page 75