The Cokin Oval Center Spot filters have an oval-shaped clear spot in the center and allow for the portrayal of an object in diffused surroundings. The black filter softens fine details with little change in contrast, while the white filter not only softens details BUT also lowers contrast. The filter effect is directly influenced by the f-stop and the focal length. The transformation is softer with wider apertures. The size of the clear circular area increases relatively with the selection of longer focal lengths.
The exposure determination should be done without the filter.
This filter measures 66 x 72mm and fits the Cokin A series holder.