Concept of HDgc Series
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Corresponding to the digital High Definition broadcasting and diversity of HDTV equipment, Canon has added a new series to its HDTV lens line up, the HDsc series. The new HDgc series supports the emergence of an important new generation of cost-effective HD acquisition systems. Adopting the advantages created by Canon's unique technology, the new HDgc lenses exhibit high MTF, high resolution and high contrast from the center of the image to its extreme edges, meanwhile maintaining its compact size and weight.
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Another important policy of Canon's is not to pollute the earth and the HDgc series succeeded in excluding harmful substances such as cadmium, PBBS, PBDPE or mercury from the mechanical parts, and at the same time incorporating lead free glass and reducing the amount of hazardous substances used in electrical parts.
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Optical Performance of HDgc Series Aberration Correction for HDgc Lenses
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In the HDTV system the pixel size is about half. Therefore, the spread of a point image caused by a spherical and even if the image is slightly out of focus, the MTF is greatly influenced as shown in Graph 1. HDgc greatly contributes to correcting and minimizing these aberrations at the same time maintaingng high MTF throughout the edge of the picture.
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Special Optical Elements
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With the goal of minimizing chromatic aberration, the HDgc series lenses utilizes special elements including an artificially re-crystalized element, 'Fluorite', with extraordinary dispersion characteristics and the newly developed 'Hi-UD' (high index ultra low dispersion) glass. Canon has succeeded in the practical use of special elements along with advanced design techniques like 'separate achromatism'.
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