Shinji Watanabe
-Product planning

Watanabe: The development concept of the S Series lenses called for four objectives: “uncompromised resolution performance,” “impressive depth expression and a beautiful bokeh effect,” “superb mobility” bolstered by the high-speed, high-precision AF system and high-performance image stabilizer function, and “excellent video shooting performance” capable of accommodating specifications beyond 4K. The first point, “resolution performance,” is generally the most demanded performance of interchangeable lenses. Needless to say, we attained high resolution performance without compromise in the development of the S Series lenses.
The second point, “impressive depth expression and a beautiful bokeh effect,” is a factor that gives a “sophisticated touch” to the image rendering performance of the S Series lenses.

In deciding on the development concept of the S Series lenses, we gave deep thoughts to exactly what “sophisticated touch” to the image rendering performance meant. Eventually, we came to a rather philosophical conclusion that we had to examine the true meaning of “capturing exactly what you see and feel.” Given this, we decided to work intensively on achieving the next point, “impressive depth expression and a beautiful bokeh effect.”

- It seems that the full-frame feature by itself would be suited for enhancing depth expression and a beautiful bokeh effect.

Watanabe: It was not so easy. Photographs must express the three-dimensional subjects on a two-dimensional surface. I think an ideal photo is one that accurately depicts a three-dimensional world with the image recorded on a two-dimensional surface. Even for a full-frame lens, whether the developers are conscious of this and how they intend to design image expressivity can change the optical design of the lens, and also determine the lens characteristics including “sophisticated touch.”
The same applies to the bokeh effect. We were very particular about creating a beautiful bokeh effect. We conducted hearings with professional photographers regarding the shape of bokeh, reduction of the “onion ring” effect, and what kind of bokeh is considered beautiful. We shared and discussed about the results of the hearings with the design team to realize the beautiful bokeh effect that only the LUMIX S Series lenses can offer.

 

- What was the key point in combining all those into a system?

Watanabe: As a system, we strove to achieve high levels of “superb mobility” backed by the high-speed, high-precision AF and image stabilizer function and “excellent video shooting performance” capable of accommodating specifications beyond 4K, both of which were called for by the development concept. To create a high-speed, high-precision AF, we utilized the ultrahigh-speed 480-fps AF control technology and incorporated new specifications and technologies including the ultrasonic assist system developed newly for the S Series, thus improving the auto focus speed and accuracy. Video shooting performance is one of LUMIX’s specialties. In the camera industry, at long last efforts are being made to achieve smooth exposure change during video shooting and to reduce lens focus breathing. LUMIX addressed those during the development of Micro Four Thirds System interchangeable lenses. The knowhow we have accumulated ahead of others is our advantage, and the S Series lenses take this advantage to the fullest.

Our aim was to recreate a three-dimensional world from two-dimensional images.

- What were you most particular about in the optical design of the LUMIX S Series lenses?

Bitou: As mentioned earlier by the member in charge of product planning, we were very particular about the beautiful bokeh effect, which we considered to be a must for the full-frame lenses, as well as about the impressive depth expression necessary for recreating a three-dimensional world from a two-dimensional image. Of course, lens functions and specifications are very important, but we regarded depth expression and bokeh effect as key factors for adding a special touch to the lens characteristics, which does not appear in the specifications.

 

- Just because a lens is full-frame does not guarantee it offers excellent depth expression or a beautiful bokeh effect, does it?

Tadakazu Bitou
-Lens optical technology

Bitou: No, it doesn’t. A full-frame lens has a shallower depth of field than, say, a Micro Four Thirds System lens. Therefore, if you are talking only about bokeh, a full-frame lens does give a greater bokeh effect. However, we realized that a beautiful bokeh effect and impressive depth expression cannot be achieved unless the optical designers were conscious of the lens characteristics from the early development stages.

- Can you tell us more about the points you were particular about?

Bitou: With respect to depth expression, we conducted evaluations of portraits. We successfully attained “impressive depth expression” by ensuring beautiful continuity of the bokeh, for example, by rendering smooth defocus gradation from the areas around the pupils to the areas near the ears when the focus is on the pupils and the aperture is fully open. Based on our belief that natural-looking depth expression is achieved by the accumulation of such detailed efforts, we strove to attain delicate expressivity that the specifications do not tell by going far beyond simple defocusing for “beautiful background bokeh.”

- What are the highlight results of the beautiful bokeh effect?

Bitou: Regarding the bokeh effect, we gave careful consideration to improving the quality of bokeh, for example, eliminating onion ring bokeh in spherical bokeh and preventing distortion of the bokeh shape near the image periphery. Designing the bokeh effect we wanted required not only optical design ingenuity but also large-diameter lenses, aspherical lenses with high surface accuracy and our company’s original manufacturing technology.

 

- I am so anxious to see pictures shot with the S Series lenses.

Bitou: We also employed other technological breakthroughs to achieve the high-speed, high-precision AF and outstanding video image quality. When a lens is made to provide higher image quality, the focus lens becomes heavier. So, it was a major challenge in both areas of optical design and lens mechanism design to achieve fast and accurate lens drive. We newly developed a double focus system and ultrasonic assist system to realize the high-speed, high-precision AF. The focus breathing suppression function and other features that improve video image quality are now becoming basic performance requirements for interchangeable lenses. LUMIX already addressed those technologies in the development of Micro Four Thirds System lenses. We have gained an advantage over others by accumulating knowhow ahead of them. This advantage was reflected and maximized in the S Series lenses. We would like customers to try the LUMIX S1R or S1 and check the operating feel. I am sure that they will feel and appreciate the high levels of function and operability, such as the fast auto focus and comfortable operation of the manual focus.

Watanabe: Today, cameras are required to provide not only higher picture taking performance but also greater video shooting performance. We developed the S Series lenses by looking many years ahead, so they have potential to satisfy future requirements. We confidently believe that the S Series will respond to the needs of not only professional photographers but also videographers and cinematographers and help them explore new image expression.