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Digital photographers contantly struggle with pattern moiré and aliasing caused by the interference between repeating patterns in the subject (such as tweed or denim fabrics) and the receptors on the CCD used to capture the image.
Originally developed to eliminate the scan lines when photographing TV screens, Caprock has modified these optical filters for use by digital photographers, to eliminate moiré. They are also effective in eliminating aliasing ("Christmas Tree light" effect). The filters are far more effective and rugged than the fragile (and exceedingly expensive) dichroic filters offered by some manufacturers.
Since they are used in front of the lens when making the shot via a 67mm thread, they eliminate the problem at the source, so there is no need for electronic re-touching.
Used with capture-backs by Phase One, Kodak DCS, MegaVision and others , the filters diffuse the source to eliminate the interference pattern (moiré) created between the CCD array and regular, repeating patterns. Since they are optical filters, rather than soft focus, image integrity and sharpness are maintained. They are also effective in eliminating aliasing (often referred to as "Christmas tree light" effect), caused by improper software interpolation of color receptor data.
Four filters are available, designated as follows: 4.0, 5.6, 8.0 and 11.0. Higher number filters provide greater sharpness at the cost of less elimination of moiré. The numbers do not correspond to f-stops, but rather to the diameter of the pattern of circles that make the filters work.
