Lense Technology

●Advanced lens design
Four Thirds lenses have not been designed simply in pursuit of high-quality optical imaging, but instead are part of a comprehensive effort to optimize the imaging system as a whole, including the image sensor and image processor. This comprehensive approach has been indispensable to achieving the high-definition picture quality of the Four Thirds system. Our final goal was to develop technology that would minimize performance degradation in fabrication and ensure that only the finest products reach the user's hands. In addition, we created advanced simulations that take optical imaging performance and fabrication errors into consideration to guarantee the achievement of the quality targets from the design stage.

●Advanced coating technology
The Four Thirds system uses advanced lens coating technology in order to achieve optimum color balance and to reduce ghosts and flare. This coating reduces reflections regardless of the light incident angle and at a wide range of wavelengths, and has been independently optimized for each lens element. Care is also taken to prevent the digital-specific phenomenon of ghosts and flare due to reciprocal reflections between the image sensor and lens element surface. Together these refinements ensure accurate representation of natural light even in photographing against the light, providing excellent imaging performance with high contrast.

●Completely electronic mount
The Four Thirds mount supports completely electronic information communication between the lens and camera body. Every interchangeable lens, teleconverter and extension tube incorporates a CPU for two-way communication with the camera body, exchanging information on lens type, focal length and F-number.
With instantaneous, accurate communication of the information required for optimum imaging, this is an intelligent lens system that embodies the new digital age.
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●Fabrication technology supporting high performance

(1) Optical glass: Ultra-precision polishing technology
Fabrication of high-performance lenses requires optical glass material that can manifest unimaginably high accuracy and high quality. For instance, the front lens element used with ZUIKO DIGITAL ED 300mm F2.8 is fabricated with ultrahigh precision at the micrometric level through long hours of polishing. Its "process accuracy" does not allow, for example, a height irregularity comparable to the thickness of hair in an area the size of a baseball stadium. The Four Thirds system is the fruit of the fusion between the most advanced computerized design technology and the skilled craftsmanship required in high-precision optical glass polishing technology.

(2) Aspherical lens elements: Mass-production of double-sided aspherical lens elements with the largest diameters (over 50mm) of camera lenses
ZUIKO DIGITAL ED 7-14 mm F4.0 uses double-side aspherical concave lens elements and has succeeded in almost perfectly correcting the distortion specific to ultra-wide-angle lenses. Fabrication of large-diameter aspherical concave lenses has been accompanied with problems due to their properties, including; 1) cracking tendency; 2) difficulties in maintaining the profile irregularity. These problems were solved and a mass-production system was established thanks to the following developments.

1) Development of dedicated forming machine
Forming a large-diameter lens requires a long period for heating and cooling of the mold and glass. To prevent shrinkage by cooling, an original forming machine was developed with powerful heating/cooling functions, enabling control of the mold with high 1C accuracy at temperatures over 600C.

2) Development of a dedicated measuring machine
An eccentricity/profile irregularity evaluation instrument was developed independently, featuring the world's highest measuring accuracy suitable for large diameters and large contact angles.

3) Ultra-high-precision mold fabrication technology
Mold accuracy is the key to the production of high-accuracy aspherical lenses. Securing the accuracy of the molds for the double-side aspherical concave lens element used in ZUIKO DIGITAL ED 7-14mm F4.0 was especially difficult because its area is more than four times larger than previous lenses. However, the problem with mold accuracy was solved with the help of the most experience mold polishers in the industry. The result is the world's most precise molding system.

(3) Low dispersion lens
Compared to an ordinary optical glass lens, the low dispersion lens presents extremely small changes in refractivity in the wavelengths from blue to red. It can improve the imaging performance of lenses by reducing the chromatic aberration (a phenomenon caused by the dispersion of light produced by deviation of the focusing point due to color differences) that causes color fringing or contrast degradation (the low dispersion lens is called SLD glass by Sigma and ED lens by Panasonic/Olympus). By improving the optical characteristics of SLD glass and ED lens, the ELD glass or Super ED lens was created. This offers optical dispersion characteristics comparable to those obtained with fluorite. Optimum use of ED and Super ED lenses (or SLD or ELD glasses) makes it possible to effectively correct chromatic aberration. The Four Thirds system utilizes these low dispersion lenses extensively in telephoto and ultra-wide angle lenses to achieve sharp, high-contrast imaging performance.

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●High mobility

(1) Optical image stabilizer (MEGA O.I.S.)
Camera shake is the single biggest obstacle to capturing clear, sharp images. Panasonic developed MEGA O.I.S. to overcome this obstacle. Featured in the LEICA D VARIO-ELMARIT lens, MEGA O.I.S. uses gyro sensors to detect camera movement caused by handshake and shifts a corrective lens accordingly to adjust the optical axis. Blurring is eliminated or minimized. Panasonic's Venus Engine LSI enhances MEGA O.I.S. performance because it is incorporated directly into the lens. This high-speed processor helps provide highly precise shake detection at a rate of 4,000 times per second, so compensation is extremely accurate. MEGA O.I.S. makes it possible to capture clear, sharp images without a tripod when taking macro shots or shooting in dim lighting, so you get greater shooting flexibility.

(2) Hyper-Sonic Motor (HSM)
Sigma-original HSM is a system featuring high drive/stop response that can reduce the drive noise. A lens incorporating HSM is capable of autofocusing at high speed and low noise, and can also be used in full-time manual focusing operation with which fine focus adjustment is possible by simply turning the focusing ring after approximate focus has been obtained with autofocusing.
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●Other lens design knowledge

(1) Floating mechanism
This mechanism divides a part of lens system into groups according to the focusing distance and lets the groups act differently when adjusting the focus. This makes it possible to correct various aberrations optimally at any focusing distance and to shorten the closest focusing distance.

(2) Inner focusing & rear focusing mechanism
Inner focusing refers to focusing by moving the intermediate groups in a lens system, and rear focusing refers to focusing by moving the rearmost group. To reduce the closest focusing distance or improve the picture quality throughout the range from distant views to closest focusing distance, the Four Thirds lenses adopt the optimum focusing methods for each model, by combining a floating mechanism with an inner focusing or rear focusing mechanism.

(3) Circular aperture diaphragm
Defocusing in pictures is important when you want to make the main subject appear more prominent. The use of a circular aperture diaphragm is effective for representing defocusing mildly without peculiarities. A lens incorporating a circular aperture diaphragm is designed to shape the aperture almost circular from the open position to the second stop, so that tasteful defocusing can be obtained near the open aperture.
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