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 KH13x4.5 KRS is a portable HDTV production lens within the 1/2-inch image format sector of the HDgc family. This particular lens is intended for users whose foremost priority is a lens that delivers a generous range of focal lengths combined with an exceptional wide field of view in a lightweight mobile package. It was specifically designed for the new cost-effective 1/2-inch acquisition systems. It is an important member of the emerging HDgc family in terms of facilitating HD imaging with equivalent operational capabilities as the established 2/3-inch SDTV systems.
ABOUT THIS LENS
Canon’s breakthrough technologies and powerful computer-aided design techniques produced the KH13x4.5 KRS, a standard HDTV lens with an excellent performance-cost optimization. In addition, it offers focal lengths of up to 59mm and a wide field of view of 75.7 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 KH13x4.5 KRS 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.