Understanding ispeed
90
i--SPEED LT, i--SPEED 2
` White Balance
The human eye automatically adjusts its colour processing in order
to make white objects look “white” in spite of varying ambient
lighting colour. When viewing video on a monitor, however, the eye
judges white based on the ambient around the monitor, not on the
ambient around the camera. For this reason, a colour camera must
also adjust its processing to compensate for the ambient lighting
and configure its output to produce the electronic version of pure
white (red = green = blue) when a white object is viewed. In this
way, the camera can render white objects as white on the monitor,
in spite of ambient light coloration. This function is called white
balance.
The Olympus i-- SPEED LT, i-- SPEED 2 provides two types of white
balance, pre --set and automatic. Several pre--set white balance
settings are provided, based on light source technologies found in
the Olympus range of industrial light sources.
The automatic function relies on the user placing a pure white
reference (sheet of paper etc.) if front of the camera, completely
filling the field of view and then pressing the WB Set button. When
this is done, the c amera will sample the reference and reconfigure
its processing electronics to render this as pure white. The
reference must not be removed until the white balance is complete,
so an on screen message shows the status of the white balance
process.
` Lighting
The Olympus i-- SPEED LT, i-- SPEED 2 has been designed to
remove most of the difficulty associated with taking high speed
video shots, but two areas of critical importance still remain, lenses
and lighting. In many cases, most of the time taken when working
with the Olympus i-- SPEED LT, i-- SPEED 2 will be used in setting
up the lighting, framing the shot and choosing the correct lens.
Earlier sections of this document have described how the shutter
time and speed setting of the camera dramatically increase the
requirement for light. The result of this is that most high speed
video applications require a large amount of lighting and this is a
common theme in the high speed video industry. As a rough guide,
most indoor shots require 500 to 2,000 watts of additional lighting.
This is traditionally provided by shining a few high power spot lights
on the target scene but, for smaller targets, the Olympus range of
industrial light sources and light guides provide ideal illumination.
Simply providing a large wattage of light is not suitable for most
applications. It is usually necessary to carefully focus and target
the light, so general purpose floodlights are not normally useful in
HSV work.
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