Interview with S5II/S5IIX Developers
We added Phase Hybrid AF to deliver faster, more accurate autofocus tracking
Tomohiro Ogami (AF)
─ Why is LUMIX S5II the first model with phase detection autofocus?
Ogami: High image quality has been a top priority in developing LUMIX cameras. Phase detection autofocus affects image quality, causing pixel loss and so on, so we used contrast autofocus and DFD technology to achieve fast and accurate autofocus. We knew that people had been asking why LUMIX so stubbornly refuses to add phase detection autofocus, but the reason we hadn’t was that we were prioritizing image quality. With LUMIX S5II we completely resolved all the image quality issues, so we decided to add phase detection autofocus.
─ How much faster is Phase Hybrid AF than contrast autofocus?
Ogami: For stills, we achieved high speed and accuracy thanks to DFD technology and processing that switches to a high frame rate during autofocus. The biggest improvement Phase Hybrid AF offers is the speed of autofocus when taking video. However, there is more to autofocus speed when taking video than simply making it fast. Previous LUMIX models allowed you to increase the autofocus speed in the custom autofocus settings, but at high speed the focus sometimes gets confused. Thanks to Phase Hybrid AF, the LUMIX S5II delivers stable autofocus at both high and low speeds, expanding the range of expressions for video.
─ Can Phase Hybrid AF be used with L-Mount lenses currently on the market?
Ogami: Phase Hybrid AF can be used with all LUMIX lenses and L-Mount lenses. The LUMIX S5II automatically switches between phase detection autofocus and contrast autofocus with DFD depending on the scene and shooting conditions.
─ Has adding Phase Hybrid AF changed the performance of low-light autofocus ?
Ogami: With the previous LUMIX S5 model, you could use low-light autofocus when taking stills down to -6 EV. This number is the same with LUMIX S5II. It has received high praise from users in real-life shooting—many have said it comes into focus even in dim lighting such as before dawn, for example. Low-light autofocus when taking video with the LUMIX S5II is markedly better than the previous model. One reason is Phase Hybrid AF, but another is its enhanced capability to detect people in low lighting in Automatic Detection mode.
─ Tell us about the recognition capabilities of the autofocus.
Ogami: LUMIX can recognize people (body, head, face, and eyes) and animals. Based on the assumption that 70-80% of scenes in video include people, we focused most effort on establishing technology that would achieve stable autofocus in recognizing people.
We provided LUMIX S5II with a new algorithm that uses distance information from phase detect and controls that help prevent switching to other people in scenes with two or three people. Going forward, we want to focus efforts on improving performance in shooting scenes of people, so that we can achieve stable performance even when there are large numbers of people.
Taking on the challenge of new possibilities of expression with an enhanced image stabilizer
Mikio Sakurai (Image Stabilization)
─ What are the features of Active I.S., the new image stabilization technology?
Sakurai: To put it briefly, it represents a great improvement in image stabilization performance when taking video while walking. In previous models, we allocated compensation to a certain extent to each direction—horizontal, vertical, and rotational—within the limits of the range of compensation when shooting video. LUMIX S5II’s Active I.S. adjusts the allocated percentage depending on the type of camera shake. For example, it strengthens vertical compensation when the camera is shaking in a vertical direction, horizontal when shaking horizontally, and rotational when shaking rotationally. Active I.S. has resulted in a significant improvement to compensation performance when shooting while walking.
─ Is it also effective with still photography?
Sakurai: Active I.S. is a feature specifically for video. For stills, the LUMIX S5II boasts the same number of stops of image stabilization performance specified by the CIPA as the LUMIX S5. We also made improvements to the application of the control algorithm, such as applying compensation to live view before shooting , so I think image stabilization has been significantly improved overall.
─ Are there limitations, such as narrowing the angle of view?
Sakurai: Active I.S. improves mechanical image stabilization control, so it does not narrow the angle of view. Body image stabilization can of course still be combined with electronic image stabilization as before. If you turn on electronic image stabilization, the angle of view becomes slightly narrower.
─ Are there certain angles of view that compensation works better with, such as wide angle or telephoto photography?
Sakurai: The main functional improvement we made was for shooting when walking. Users are sure to notice the effectiveness when shooting with a wide angle lens while walking. The enhanced control algorithm is also advantageous for fixed telephoto shots. And combining the technology with a lens that has lens image stabilization is more effective than our standard control systems.
─ Is it effective even when panning from side to side?
Sakurai: In marketing LUMIX S5II we have emphasized that compensation for shooting while walking has been enhanced with Active I.S., but actually, image stabilization in shooting video has been improved overall. When developing the camera, we repeatedly evaluated a variety of situations of shooting while walking, as well as for handheld shooting. This included situations when the panning speed is fast, the user suddenly changes their position, and the angle of view suddenly changes. As a result, we implemented a system that would deliver smooth compensation even in such situations.
─ Did greatly improving image stabilization affect the size of the camera?
Sakurai: The main thing we improved was the control algorithm. We kept mechanical revisions that would impact the size to a minimum. As you can see there is almost no difference in the size compared to the LUMIX S5.
Interview with S5II/S5IIX Developers