This paper introduces a design of telephoto zoom lens with the built-in teleconverter, focusing on the AF-S NIKKOR 180-400mm f/4E TC1.4 FL ED VR. In recent years, professional photographers are demanding more convenience and higher image quality. For these needs, we developed the AF-S NIKKOR 180-400mm f/4E TC1.4 FL ED VR telephoto zoom lens, by improving its usability and optical performance compared to the previous model. Especially in terms of optics, we 1) expanded the focal length of the wide-angle end from 200mm to 180mm, 2) integrated 1.4x teleconverter, 3) designed it in consideration of its usability (e.g. weight, torque of zoom or focusing ring, diameter of lens barrel) . The above features have achieved by using 4-group zoom type design consisting of PNPP (positive, negative, positive and positive), and separating the focus part from the zoom part.
It will further explain how we have simultaneously realized high optical performance and usability, especially focusing on optimized optical power distribution, lens configuration, glass material combination and layout of functional lens groups (e.g. image stabilization, the built-in teleconverter).