Canon HJ21EX7.5B BROCHURE

Canon’s Philosophy

Canon has always developed new technology with four basic philosophies, "High Quality of Picture", "Ease of Operation", "High Specification" and "Minimize Environmental Impact". Canon's HDTV lenses are, so to speak, a compilation of our basic philosophies. Canon is the only manufacturer to offer a complete line of HDTV lenses to match our customers requirements. Complete "Customer Satisfaction" is our goal.

Overall Comparison Between HDTV and SDTV

Whereas one frame of the conventional SDTV (ie NTSC) system consists of 480 scanning lines, the number of scanning lines is more than 1.5 times that for the HDTV system. Furthermore the density of the scanning lines are even higher because the HDTV system has an aspect ratio of 16:9, which is wider and shorter in height than that of the normal SDTV (4:3 aspect ratio) system. The spatial frequency required for the HDTV system is about twice that required for the NTSC system. Overall, the resolution of the HDTV system is about twice that of the NTSC system and therefore, the lens requires much higher performance than the conventional lenses.

Canon’s Technology

2/3 inch							HDTV			SDTV
Image format							9.6 5.4			8.8 6.6
Nominal frequency							600TVL			400TVL
Spatial frequency							55line pairs/mm		30line pairs/mm
							HDTV	SDTV
								4:3
							16:9
6.6			5.4				11
							8.8
							9.6

Canon proudly offers our Broadcasting Lens Technology, . The technology consists of two meanings that start with the letter "e". One is the "ecological design", a design harmless to the environment. The other is the "enhanced digital" technology which improves the performance of the digital drive unit. Of course the new technology inherits all the advantages of its predecessor, the HDxs technology, which includes the advanced optical design concept, based on the X-Element technology.

Enhanced Optical Technology

Special Optical Elements

Canon has always made an effort to research special optical elements since our beginnings in this industry with the goal of minimizing chromatic aberration. These efforts have included an artificial element, "Fluorite", with extraordinary dispersion characteristics and the newly developed"Hi-UD"(high index ultra low dispersion) glass. Canon has succeeded in the practical use of special elements along with advanced design techniques like "separate achromatism". Canon TV zoom lenses carry a "Green Ring" on the focus barrel, a symbol of our high quality. Canon has developed a break through in optical design technology known as the "Power Optical System" whose heart is the "X-Element". By using the "X-Element" to its maximum power in the specially designed optical layout, higher specifications and quality can be achieved in smaller and lighter lenses. The lenses designed using the "Power Optical System" are known as the "XS-series".

Aberration Correction for HDTV Lenses

The pixel size is about half in the HDTV system, and therefore the spread of a point image caused by a spherical aberration, coma, etc. should be diminished to about half. Even if the image is slightly out of focus, MTF is greatly influenced. The graph 1 shows how MTF varies when the focus changes. Canon HDxs series lenses employ the HD version of the Power Optical System, which incorporates the X-Element. HDxs greatly contributes to correcting and minimizing these aberrations at the same time, maintaining high MTF throughout the edge of the picture (graph 2).

100
90
80
70
60
MTF(%)
50
40		NTSC 400TVL (30lp/mm)
30
		HDTV 600TVL (55lp/mm) F1.6
20
10
0
0.02		0.01	0		0.01	0.02
			Defocus(mm)
		<Graph 1>
100%					HD
			NTSC
MTF
0
Center		Middle			Corner	Edge

Image Hight

Enhanced Digital Drive	<Graph 2>

All lenses are equipped with an informational display and Digital Function Selector, an X-Y axis switch, so that the user can customize the enhanced digital functions much more easily and precisely. This new design enables the user to fully bring out the digital functions.

Main Features

Shuttle Shot

By memorizing any two focal lengths, the Digital Drive can automatically "shuttle" between the two points, moving in either direction.

Framing Preset

An angle of view can be preset in either of two memories and the lens will zoom to that position by pushing a simple button. During a performance, framing preset will reproduce the zoom position decided upon at the rehearsal. It's easy to repeat the same zoom as often as you like at the highest speed or in a preset zoom speed.

Speed Preset

A specific zoom speed can be preset in memory and it is possible to repeat the zoom speed as often as you like by pushing a simple button.