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Wednesday, October 26, 2016
  • CANON KH 21ex5.7 IRSE Lens

Canon KH 21ex5.7 IRSE Lens


Availability: Call for availability


Quick Overview

The KH21ex5.7 is a telephoto portable HDTV production lens within the 1/2-inch image format sector of the HDgc family.


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, broadcast and cable news photographers with the priority to be able to shoot over long distances combined with reasonably wide angle capture in a lightweight (4.1 lbs) mobile production lens system with very good HDTV performance. It was specifically designed for the new Sony HD XDCAM camcorders, 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.

The KH21ex5.7 mobilized the best in portable EFP optical design criteria to achieve a remarkable lens offering with 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 a 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.

Four significant technologies converge to produce the KH21ex5.7 portable HD production lens system that has been tailored to partner with today's highest performing HDTV portable cameras and camcorders:

Optical Technologies
Newly developed optical materials combined with the very latest lens element design innovations and multilayer coatings - that produce an unsurpassed pristine imaging system for the most discerning production team.

Internal Focus
A Canon design innovation that uses a floating optical system to better control chromatic aberrations

Digital Technologies
New third-generation enhanced digital servo systems using Canon-developed 16-bit optical rotary encoder devices introduce entirely new value-added creativity to handheld acquisition systems

Enhanced Digital Drive technology - encompasses a microcomputer driven servo control that embodies position memory and user-defined digital functionality to significantly empower the camera operator charged with creative shaping of the image presented to the camera sensors

16-bit rotary encoder for aperture control reports to the associated camera Iris control system (10-bit compatibility)

Maximum Zoom speed is 0.5 seconds and Focus is 1.5 seconds

Mechanical Technologies
Ergonomic mechanical design that produced this HD lens having the same size and weight as its SDTV predecessor

Compact digital servo drive unit is mounted to the lens at a 12.5 degree angle for comfort and balance

Magnesium alloy body for light weight and exceptional durability

Ecological Design
All contemporary Canon lenses avoid the use of materials and substances potentially harmful to the environment. Lead has been removed from all optics and other identified substances from all components comprising the composite lens system. 

Product Category ENG/EFP Lens
Product Series KH20ex5.7 IRSE
Image Composition
Object Image Format 1/2 inch
Aspect Ratio 16:9
Object Image size 6.97 mm (H) x 3.92 mm (V)
Zoom Ratio 21 X
Focal Length Range 5.7~120mm
Focal Length Range with Extender 11.4~240mm
Angular Field of View At 5.7mm
62.9 o (H) x 38.0 o (V)
At 120mm
3.3 o (H) x 1.9 o (V)
Angular Field of View with Extender At 11.4mm
31.5 o (H) x 19.0 o (V)
At 240mm
1.7 o (H) x 0.9 o (V)
Optical Brightness
Maximum Relative Aperture (F-Number) 1 : 1.4 at 5.7~86mm
1 : 1.95 at 120mm (Ramping Characteristic)
Maximum Relative Aperture (F-Number) with Extender 1 : 2.8 at 11.4~172mm
1 : 3.9 at 240mm (Ramping Characteristic)
Scene Composition
MOD From Front of Lens 0.8 Meter (10mm with Macro)
Scene Object Dimensions at MOD 92.2 cm x 51.9 cm at 5.7mm
4.3 cm x 2.4 cm at 120mm
Scene Object Dimensions at MOD with Extender 46.1 cm x 26.0 cm at 11.4mm
2.2 cm x 1.2 cm at 240mm
Physical Attributes 6.7in (169.4mm) 4.4in (111.9mm) 8.6in (217.5mm) 3.9lbs (1.79kg)
Width 6.7in (169.4mm)
Height 4.4in (111.9mm)
Length 8.6in (217.5mm)
Weight 3.9lbs (1.79kg)