The world’s major professional video manufacturers have
introduced a diverse range of low-cost tapeless HD camcorders and
tape-based HDV professional camcorders. Various design strategies
have been adopted by the manufacturers to decisively drive down
the costs of these HD acquisition systems. They include different
image format sizes, subsampled imagers, and contemporary digital
recording techniques. In support of these products Canon designed
an entire family of cost-effective HD ENG/EFP lenses that seek to
match both the performance and the costs of these diverse and still-emerging
HD acquisition systems. To distinguish this level of lens within
the overall Canon HD optical hierarchy they are identified by the
logo HDgc – to clearly differentiate them from the already
established high performance HDxs line of 2/3-inch portable lenses.
These acquisition systems have been developed in response to the
broadcast industry’s rapidly growing interest in transitioning
to HDTV Newsgathering, HD reality shows, and other lower-budget
HD productions. They also directly address the increasing adoption
of HD digital origination by the growing independent filmmaking
market sector. In addition, they are anticipated to foster growing
interest in HD within the broad B2B market sectors. To support this
extensive flexibility in HD acquisition systems, the new HDgc family
includes 2/3-inch, 1/2-inch, and 1/3-inch lenses.
The KH16ex5.7B IRSE standard lens is intended for users whose foremost
priority is a lens that delivers a generous range of focal lengths
combined with a wide field of view in a lightweight mobile package.
It was specifically designed for the Sony HD XDCAM camcorders, which
utilize three 1/2-inch 1440-element CCD imagers. It is an important
member of the HDgc family in terms of facilitating HD imaging with
equivalent operational capabilities as the established 2/3-inch
ABOUT THIS LENS
Canon’s breakthrough technologies and powerful computer-aided
design techniques produced the KH16ex5.7B IRSE, a standard HDTV
lens with an excellent performance-cost optimization. In addition,
it offers focal lengths of up to 91mm (or 182mm with extender) and
a wide field of view of 62.9 degrees. It is a design that directly
responds to the expressed creative desires of broadcasters and HD
producers for low-cost HD acquisition system.
The KH16ex5.7B IRSE represents a fine compromise between the demands
for mobility in a handheld HDTV camera system and the high imaging
performance requirements for HDTV production. The requisite optimization
strategies to achieve this balance sought a high MTF over the entire
image plane, minimization of chromatic aberrations, and maximization
of image contrast. Preservation of a high MTF at the wider-angle
focal lengths (where scene detail can be particularly high) was
a special priority.
Relative light distribution was optimized for the more open aperture
settings and this uniformity of brightness across the image plane
combined with the high contrast and excellent picture sharpness
produces vividly clear HD pictures. Contrast was extended by careful
control of black reproduction – with optical and mechanical
design innovations that substantially reduced flare, veiling glare,
and any internal reflections. Tight control of the geometric distortion
at wide-angle settings constituted another central design imperative.
The lens spectral transmittance characteristic was closely coordinated
with that of all of the major portable cameras to ensure adherence
to the HDTV colorimetric standards and to additionally support flexible
creative control of color reproduction.