| 主权项 |
1. A barrel-based white balance filter, comprising a white balance unit, said white balance unit comprising a barrel and a white balance component axially adjustably mounted in said barrel, wherein:
said barrel is prepared from an opaque material and attachable to a camera lens of a camera directly or by means of an engagement thread thereof; the white balance component is a milky white or gray filter having a milky white or gray annular rim axially extended from the periphery thereof, and mounted in said barrel and axially movable relative to said barrel between an extended position and a fully received position, said milky white or gray annular rim being completely received in said barrel and protected by said opaque barrel against the radiation of vivid light or reflected light during a manual white balance operation when said white balance component is in said fully received position, enabling a manual white balance system of the camera using the barrel-based white balance filter to measure the average white balance value of the viewing scene accurately. |
