Canon UHD DIGISUPER 90 产品宣传册

Use of a zoom system and floating focus has reduced the variations 
in the optical aberrations associated with zooming and focusing, 
thereby achieving a level of aberration correction commensurate 
with 4K. Furthermore, through the use of fluorite and UD glass and 
by means of optimal lens element groupings, longitudinal chromatic 
aberration and lateral chromatic aberration have been minimized. 
This has resulted in visually pleasing images on large UHD screens 
with minimal loss of sharpness and minimized color fringing on high  
contrast edges.

In order to support the trend for 4K to offer ever-higher levels of 
definition, lens element surface precision higher than that for HD lenses 
is required. To this end, an advanced new lens processing technology and 
high-grade measuring technology that Canon had been developing were 
mobilized, enabling us to come up with the technology for mass-producing 
ultra-high-precision lenses that support large-aperture lenses in the 200 
mm-diameter class.

When it comes to 2/3” 4K, even the slightest dimensional errors or 
assembly errors in the components used can significantly affect the 
images obtained. Canon accordingly increased the precision of the key 
optical components and their individual mountings while simultaneously 
combining precision assembly tools and measuring equipment to improve 
the precision levels of assembly and adjustment.

With the emergence of high dynamic range (HDR) cameras the design of 
the associated lenses acquire a whole new importance. Very sophisticated 
multilayer optical coatings are deposited on every lens element surface to 
elevate the light transmission through the lens while curtailing the optical 
reflections that can contaminate scene black level with flare and veiling glare. 
The goal is to elevate the contrast level of the nominally exposed scene to 
the highest degree possible – a key aspect of increasing dynamic range. In 
addition, the lens must reproduce specular highlights within the scene as 
faithfully as possible without any attendant stimulation of optical ghosts. 
Here too, the optical anti-reflection coatings play a pivotal role. The separate 
optical ghosting that can be stimulated by off-axis highlights (from the sun 
and other excessive highlights) are carefully managed by a multi-strategic 
design entailing internal mechanical structures.

CANON’S TECHNOLOGIES THAT ACHIEVE 4K

Each 2/3” small-format 4K pixel is equivalent to approximately 2.5 m, which is one-half of the size of the 2/3” HD pixels. These 
are approximately 1/2.7 smaller than the pixel size of the 4K Super 35mm image sensor. This means that, for these lenses, it is 
extremely important to establish the high-grade design and production technologies that will help ensure the requisite 4K UHD 
image sharpness while minimizing optical aberrations. Described below are the latest technologies Canon has developed and is 
utilizing to achieve these goals.

The Canon 4K lenses employ internal lens-barrel designs as well as lens coating 
technologies that prevent reflections to minimize the occurrence of ghosting 
and flaring, enabling the capture of High-Dynamic Range (HDR) video, which 
has recently been growing in popularity. In particular, the minimization of 
chromatic aberration in the blue channel and red channel effectively works for 
a wide color gamut that is another important element required by HDR video.

In 2/3” 4K cameras, the image sensor pixels are smaller than those for HD 
cameras so the depth of field is shallower compared with that of HD cameras. 
As a consequence, the principle involved dictates that if the focal length, 
f-number and angle of view are the same, it will become tougher to achieve 
accuracy in focusing. Canon’s 4K broadcast lenses are the product of exacting 
design and careful manufacturing while high performance servo motors and 
high-resolution encoders are incorporated into the lens bodies and controllers 
to enable focusing with the high accuracy demanded by 4K shooting.