Silicon Imaging SI-2K User Manual page 30

Look Control
The idea behind Iridas Looks is to SIMULATE the color characteristics of the
target medium such as a Filmprint or even an HD Monitor, since the RAW im-
age itself looks flat.
Please note
that this is only a tool to simulate colors inside the SiliconDVR without affecting
the RAW Image itself! Iridas .look files represent non-destructive color meta-
data based on 3D look up tables in a 32-bit floating point environment.
These can be modified with the integrated Iridas Speedgrade Version, which
can be accessed through the hot spot button upper middle of the preview im-
age.
Optional the .look files can be generated with the IRIDAS Software such as the
Speedgrade Product Family and imported to the SI-2K Recoding Unit through
USB connection.
SiliconDVR already carries preset .look files (C:Program Files\ Silicon Imag-
ing\Silicon DVR\Data\*.look
Exposure Control
ISO Rating
The CMOS sensor in the SI-2K is approximately „daylight" balanced for 5600K
at ISO 160.
When shooting green-screen or blue-screen footage, in order to prevent higher
digital gains (that in-turn produce higher noise) in the blue and green channels
in order to match the response of the red channel, it is suggested to shoot
with daylight balanced light-sources. Also daylight balanced light-sources will
extend the „useable" dynamic range of the image around 1/3 to 1/2 f-stop (be-
cause the red-channel will not clip first).
With Tungsten Lighting and shooting at 3200K the sensitivity is approx. ISO
250.
Shutter
To convert from a shutter based on a time-based method (such as 1/Xth of a
second) to a shutter based on a degree angle correlating to the spinning reflex
mirror of a film camera, use this equation:
1 / [ ( 360 degrees / Target angle ) * Target Frame Rate ] = Time based shutter
(in 1/Xth of a second format)
So for instance, a 180 degree shutter at 24fps will equate to:
1 / [ ( 360 degrees / 180 degress ) * 24 ] = 1/48th of a second
A 144 degree shutter angle at 24fps will equate to:
1 / [ ( 360 degrees / 144 degrees ) * 24 ] = 1/60th of a second
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