The Cokin Filter P067 Center Spot Blue allows you to emphasize the centre of an image while blurring the surrounding area with a blue colour. With this filter you can give your pictures a dramatic colour effect.
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 should 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.