Optical filter, method of making optical filter, light amount adjusting apparatus and optical equipment

摘要

An optical filter which can be manufactured at low cost and is excellent in optical characteristics is disclosed. The optical filter has a transparent substrate and a first layer which is formed on the surface of the transparent substrate. Here, the first layer has a first area which is substantially transparent and a second area which has colored ink and is light-amount adjustable, and the optical path lengths with respect to the first and the second areas are substantially equal.