KH 21ex5.7 IRSE

In 2006 Canon is introducing a new family of portable HDTV lenses for EFP, ENG, and a range of corporate and business industrial applications. In so doing, an important hierarchy in HD optics is being created. It is important because of the highly innovative developments by the world’s major professional video manufacturers in their recent introduction of a diverse range of new 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 is designing an entire new family of cost-effective HD 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 being identified by the logo HDgc – to clearly differentiate them from the already established high performance HDxs line of 2/3-inch portable lenses.

These new 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 will include 2/3-inch, 1/2-inch, and 1/3-inch lenses.

The KH21ex5.7 is a telephoto portable HDTV production lens within the 1/2-inch image format sector of the HDgc family. This particular lens is intended for producers and broadcast and cable news photographers having as their foremost priority the ability to shoot over long distances combined with reasonably wide angle capture in a lightweight (4.1 lbs) mobile production lens system having very good HDTV performance. It was specifically designed for the new HD XDCAM camcorders of Sony, which utilize three 1/2-inch 1440-element CCD imagers. 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
The KH21ex5.7 mobilized the best in portable EFP optical design criteria to achieve a remarkable lens offering focal lengths up to 120mm (or 240mm with extender) and a wide-angle of almost 63 degrees horizontal. Combined with an exceptionally high sensitivity (F1.4 maximum aperture) this is a lens that can encompass an unusually broad range of shooting situations.

The KH21ex5.7 utilized breakthrough technologies and powerful computer-aided design techniques to produce a very wide-angle HDTV lens with an excellent performance-cost optimization. It is a design directly responding to the expressed creative desires of broadcasters and HD producers for low-cost HD acquisition system.

The KH21ex5.7 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. Relative light distribution was optimized for the more open aperture settings and this uniformity of brightness across the image plane combines with the high contrast and excellent picture sharpness to produce 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.