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| The aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size. |
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This lens provides high optical performance while maintaining a compactsize. For example, the 12-24 mm f/4.5-5.6 EX DG ASPHERICAL lens widensthe range of wide-angle lenses, and it provides distortion-free images withimage reproduction performance equivalent to that of a single-focal lengthlens. Aspherical lenses allow the production of high-quality images fromcompact, lightweight telephoto zoom lenses.
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| OS (Optical Stabilizer) Function |
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| This function utilizes a built-in mechanism that compensates for camera shake. It dramatically expands photographic possibilities by alleviating camera movement when shooting by hand held camera. |
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The OS function uses two sensors inside the lens to detect vertical andhorizontal movement of the camera and works by moving an optical imagestabilizing lens group to effectively compensate for camera shake. The OSfunction offers the equivalent of using a shutter speed 4 stops faster makingit suitable for telephoto and low lightphotography. As the stabilizing feature is built intothe lens, it can be designedspecifically to suit the characteristicsof that lens. This provides precisecompensation for camera shakethroughout the entire zoom range.This also enables the correctlystabilized image to appear in theviewfinder aiding autofocus andcomposition.
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Camera shake correction mechanism OFF
Camera shake correction mechanism ON |
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This lens uses a motor driven by ultrasonic waves to provide a quiet, highspeed AF.
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| To ensure stability in focusing, this lens moves the inner lens group or groups without changing the lens' physical length. |
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| This lens is equipped with a system that moves the rear lens group for highspeed , silent focusing. |
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| Conventional focusing has normallybeen performed by moving either all lens groups as a fixed unit or onlythe first lens group. AF cameras are now widely used, even for close-upphotography. Consequently, demand has arisen for a focusing system thatwill keep the length of the lens unchanged while showing little fluctuationof aberration. In response to this demand, SIGMA has developed a newinner focus system that moves two lens groups inside the telephoto andtelephoto MACRO lenses. This system has floating elements thatsubstantially improve the close-upcapability of the lens. The superwide angle lens having a large front-lens uses a rear focusing system tomove the rear-lens apparatus andenhance the floating effect, and the18-200mm F3.5-6.3 DC features aninner focusing system to move thesecondary lens group duringfocusing. This lens has a minimumfocusing distance of 45 cm / 17.7inch throughout entire zoom range.The rear focus system ensures high-speed focusing with the wide lens20mm F1.8 EX DG ASPHERICALRF. |
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 Although telephoto zoom lensescan be used closer to the objectthan fixed focal length telephotolenses, there is still a minimumshooting distance. SIGMA hasmade this minimum distance smaller and developed the zoom MACRO lensfor taking close-up photographs of the same quality as those taken with aregular MACRO lens, while maintaining the performance specific to anAPO lens. Rather than carrying around the cumbersome accessoriesrequired for close-up work, the photographer can now take photographs ata magnification of 1:2 (one halflifesize) using a telephoto lens, byquickly shifting from the normalsetting to the full macro setting. |
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| In order to attain the highest quality images, the APO lens has been made using special low-dispersion (SLD) glass and is designed to minimize color aberration. |
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| SIGMA's APO zoom lenses minimizecolor aberration. As the refractiveindex of glass depends on thewavelength of light,color aberrationoccurs when different colors formimages at different points. Thisproblem often occurs with telephotolenses,but the Special Low-Dispersion(SLD) glass and Extraordinary LowDispersion (ELD) used in SIGMA'sAPO lenses helps to compensate forcolor aberration, thereby allowingthem to produce of sharp images. |
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| Conv (APO Teleconverter EX) |
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This lens can be used with the APO Teleconverter EX. It can increase the focal length and will interface with the camera's AE (automatic exposure) function.
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The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.
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| These are high-performance lenses optimized for digital cameras. They are ideal not only for 35 mm digital SLR cameras and film digital SLR cameras but also for APS-C digital SLR cameras. They deliver superior image quality by correcting for all types of aberration, especially distortion, and they have high resolution capability because they minimize chromatic aberration of magnification, which is particularly a problem for digital cameras. What is more, these lenses incorporate optical designs optimized for digital cameras and Sigma's own Super Multi-Layer Coating technology, so they reduce flare and ghosting due to reflection between the image sensor and lens surfaces, and they provide high contrast and a wide range of tone. They also provide enough peripheral brightness with little vignetting. |
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These are dedicated digital SLR camera lenses with an image circle designed to suit image sensors that correspond to APS-C size. Inhouse technology accumulated through the development of our digital SLR camera was used to optimize optical performance for our digital lenses. This is a high-performance lens series that fuses technology such as lens power layout and coating design with the know-how Sigma has built up over many years of developing interchangeable lenses for SLR cameras. By reducing the diameter of the image circle, Sigma has achieved a more compact, lightweight lens series.
* An image sensor larger than those corresponding to the APS-C size cannot be used in digital SLR cameras, 35 mm SLR cameras, or APS film SLR cameras. If such an element is used, vignetting will occur on the picture surface.
The angle of view varies depending on which camera model the lens is used with.
35mm format is approximately 1.5 - 2.0 times the focal length of the lens being used.
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| The floating system is used to controlthe focus. This system moves thedifferent lens groups in the opticalsystem to different positions, thereby minimizing the telescoping distanceand the fluctuation of aberration atdifferent shooting distances. Thissystem is particularly effective formacro lenses (which encompass a widerange of shooting distances) and wide-angle lenses (for Single-Lens Reflexcameras) whose lens composition isasymmetric. SIGMA uses the floatingsystem for the MACRO 50 mm f/2.8 EXDG lens and the large-aperture wide-angle 28 mm f/1.8 EX DG ASPHERICALMACRO lenses. |
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| The DF (Dual Focus) system disengages the linkage between the internalfocusing mechanism and outer focusing ring when the focusing ring ismoved to the AF position. This system provides easy and precise handlingof the lens, since the focusing ring does not rotate during autofocusing. Thewide focusing ring also enables easy and accurate manual focusing. |
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