UHDTV has entered the practical stage, as exemplified by the start of 4K/8K satellite broadcasting in December 2018 in Japan. Advancements in broadcast television camera systems is remarkable with 2/3-inch tri-sensor cameras evolving from HDTV to 4K, while at the same time 4K optical performance has been achieved for the associated interchangeable lenses. A contemporary requirement for broadcast television lenses is extra high zoom ratios that offer dynamic and seamless moving image expression, while avoiding lens exchange during live productions such as sports broadcasts and concert stage performances. <p> </p>In this paper, we introduce the optical design concept applied to the latest 2/3-inch 4K zoom lens having a higher than 80x zoom range. The paper will further explain how Canon has realized 4K optical performance – while maintaining physical size and zoom ratio equivalent to the latest HDTV lenses – by referring to patent-pending technologies encompassing optical power layout, lens construction, and glass material combinations.
Central to the rapid evolution of 4K image capture technology in the past few years, deployment of large-format cameras with Super35mm Single Sensors is increasing in TV production for diverse shows such as dramas, documentaries, wildlife, and sports. While large format image capture has been the standard in the cinema world for quite some time, the recent experiences within the broadcast industry have revealed a variety of requirement differences for large format lenses compared to those of the cinema industry. A typical requirement for a broadcast lens is a considerably higher zoom ratio in order to avoid changing lenses in the middle of a live event, which is mostly not the case for traditional cinema productions. Another example is the need for compact size, light weight, and servo operability for a single camera operator shooting in a shoulder-mount ENG style. On the other hand, there are new requirements that are common to both worlds, such as smooth and seamless change in angle of view throughout the long zoom range, which potentially offers new image expression that never existed in the past. This paper will discuss the requirements from the two industries of cinema and broadcast, while at the same time introducing the new technologies and new optical design concepts applied to our latest “CINE-SERVO” lens series which presently consists of two models, CN7x17KAS-S and CN20x50IAS-H. It will further explain how Canon has realized 4K optical performance and fast servo control while simultaneously achieving compact size, light weight and high zoom ratio, by referring to patent-pending technologies such as the optical power layout, lens construction, and glass material combinations.