S-R2060_2

We also reanalyzed the functions required for the zoom lens barrel and strove to use the smallest parts possible and to minimize the number of parts. We conducted structural analysis simulation in reviewing the parts joining conditions, and we integrated multiple functions into a single part in efforts to reduce the size and weight. Downsizing required higher dimensional accuracy, so we forecasted the dimensions of the final molded parts by conducting flow analysis simulation of the resin flowing in the molds during the molding process. Thanks to these efforts, we have achieved a stunning dimensional accuracy with an error of only several microns or less.

As a result of diligently pursuing the target specifications based on the above mentioned optical design approach and mechanical design approach, we successfully attained the focal length of 20 to 60 mm, F3.5 to F5.6 and the barrel size of Φ77.4 mm x approx. 87.2 mm without compromising the S-R2060’s high optical performance. This means we have realized for the first time in the world a high-performance compact zoom lens covering from an ultra-wide-angle range to a standard range.

The next topic is closest focusing distance. The focusing distance for taking pictures for table photos is generally said to be 30 cm. However, we felt 30 cm was still too far for taking good pictures of food or small items from the sitting position, so we examined ways to reduce the closest focusing distance.

For the optical design, we opted for a 5-component zoom configuration for the correction of aberrations over the entire object distance range. In addition, we increased the space between the focus lens group and the final lens on the wide-angle side as much as possible to provide a sufficient focus stroke.

The LUMIX camera’s contrast detection system utilizes the AF control that operates 240 times a second using a stepping motor and the DFD technology to detect contrast peaks quickly for accurate and fast focusing. Therefore, high-speed drive control is possible even though the focus stroke is long.

We used both optical simulation and actual shot images to closely study the image rendering performance, and set the closest focusing distance to 15 cm because the resolution performance would be high enough to satisfy the users at this distance limit.
The tip of the lens can be brought as close as about 5 cm from the subject; however, at this distance the lens surface can accidentally contact the subject and gets dirty during macro shooting. To prevent adhesion of dirt, the surface of the lens closest to the subject has a fluorine coating.

Beautiful bokeh is one of the highlight features of the S series lenses. The S-R2060 lets the user add a dramatic bokeh effect to the background while taking advantage of the deep perspective unique to the wide-angle lens. To realize beautiful bokeh, we used our original image simulation tool that was created before for the development of our PRO lenses to reproduce images with bokeh and optimized the spherical aberration in order to achieve balance between resolution performance and bokeh effect. As a result, the S-R2060 offers beautiful bokeh effects and provides high resolution performance at the same time. It also realizes a near-circular bokeh shape with minimal vignetting even at the image periphery.

We also examined the mechanical design for improving the quality of bokeh. The S-R2060 features an iris diaphragm with nine aperture blades to create a natural, circular bokeh shape. When the number of aperture blades is increased, the shape of the diaphragm opening becomes closer to a perfect circle, thus making the bokeh rounder and more natural-looking. What’s more, the contours of the individual blades that form the opening are designed to resemble the shape of smoothly connected circles so that the nine same-shape blades create a nearer-perfect-circle opening.

In the next blog, we will discuss about the optical design for suppressing focus breathing and how we achieved both high design quality and excellent operability.