The Cokin Filter P073 Center Spot Wide Angle Grey 2 allows you to emphasize the centre of an image while darkening the surrounding area. This filter comes in two gradations: P072 Grey 1 and P073 Grey 2, with the 073 filter having a greater effect than the 072 filter. With the P072 filter you can give your photos a more dramatic look.
Working with the P073 filter
The filter is directly influenced by the set aperture and the focal length. If you use a larger aperture, the filter will have a softer effect on the photo. The size of the circular area that is rendered sharp becomes larger when using a longer focal length. Exposure metering must be done without the filter attached to the lens. If your camera has spot metering, you do not need to remove the filter from the lens to determine exposure.