Schneider 110mm Center Filter (#5) for 165mm f/8

This is a center filter used to correct illumination falloff on the Super Angulon 165/8 wide angle lens. It has a filter factor of 3x in the center (1.5 stops) and is clear at the edges. The mounting thread is 110mm x 1.0 with a front accessory thread of 125mm x 1.0 (discontinued filter size).