To design a lens that can be fitted to the compact dimension of the XA body was one of the hardest problem of the XA development. Maitani insisted on a 35mm lens to be fitted into a body of 4cm thick. However, only a 31mm wide angle lens can be fitted into it by using the conventional design concept. Moreover, by shortening a Tessar type 35mm lens, the maximum shortening achieved is 1mm and not the required 4mm. The lens design team headed by Yoshisada Hayamizu finally came up with the idea of using a "Reverse Retrofocus Type" or "Telephoto Type" lens design. It was the first time that a "Reverse Retrofocus Type" 35mm wide angle lens was designed. (Normally, this type of lens design was used to make telephoto lens for slr cameras.) To provide focusing without extending the lens outward, an inner focusing mechanism was adopted.
