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The Next Step
as printed in Fall/Winter 99 edition of Profiles
magazine.
Greetings from Roger Macie,
If you're a regular subscriber to ProSource's Profiles
magazine, you've already read this maintenance tip in their latest
fall/winter 99 edition, but we'll be posting more in between Profile
editions, and notifying you as they come.
In an earlier “Profiles”, I wrote “Call for Uniformity”
about the need for a broadcast industry camera alignment standard. The
next issue, “The Ultimate Standard” discussed that standard which was
developed using DSC Labs’ “Optical Signal Generator” and the SMPTE
specification, which would allow the popular broadcast field cameras to
produce near true color and also match each other.
It’s been over three years since “The Ultimate Standard”
and I have had a chance to reflect on its success. With well over a
thousand cameras set up, feedback has been totally positive. Not only
have crews spent less time with multi-camera setups. But producers also
have been very pleased with their video. Network news magazine producers
have been its biggest supporters because of the consistency amongst
crews with different cameras. What made this possible was accurate
preset gains, proper tracking of black levels, consistent gamma, and
improved colorimetry.
This brings us to the “Next Step” which is a result of
the new digital video revolution. With digital cameras replacing their
analog counterparts, another tool is now available to videographers’
scene files or set up cards. With most cameras’ alignment controls
becoming digital menu items, alignment parameters can be changed and
stored.
This ability to change camera alignment parameters now
allows videographers the ability to deal with difficult lighting
conditions. By changing gamma characteristics, white compression, and
black stretch adjustments, it is now possible to shoot acceptable video
in extreme high contrast lighting conditions such as sun/shade
situations. One videographer was able to get usable footage in a forest
with streaming sunlight which, without such a feature, would have been
impossible without expensive lighting equipment. Shooting in low
contrast conditions like snow and haze, and even desert scenes can be
improved with adjustments, which lower the camera’s gamma curve. Film
looks can be created to take the edge off of video while at the same
time extending the exposure latitude, both in the darks and the
highlights.
Can these specialty cards be purchased for all digital
cameras? That depends upon the consistency of matrix, firmware versions,
and lens files. Some digital cameras have colorimetry which varies from
camera to camera, and are not able to compensate presets gains and
flares for different lenses. Newer cameras such as the Ikegami HL-V59
have not only a lens file system, but also a consistent colorimetry
look, which can allow for looks to follow cards.
I have found that with all digital cameras without lens
files it is possible to create specialty set up cards once the initial
camera set up has been done with its working lenses. This allows for
preset gains to be set properly and flares to be set. Because of the
lack of lens files on some cameras, preset gains are set up to the
coolest looking lens. This assures either proper color balance or
slightly warmer video, depending on the lens used. Once the colorimetry
is set up, the base line for multiple looks is there, This is important
for those manufacturers who ship new cameras separate from their lenses.
Not only are flares and presets not set, but most alignments are left
zeroed out with generally less than pleasing results.
Take care,
Roger |
