The Cokin H250A Gradual ND Kit consists of a set of three grey-gradient filters to balance light intensity within a scene. This is especially true in situations where you do not have total control over light, such as in high-contrast landscapes. Often in strong sunlight, the sky will start to fade and the foreground will become too dark, losing detail. The Cokin Gradual Gray Filter eliminates the difference in light intensity, resulting in a balanced exposure.
Included filters
The kit includes the Cokin 121L filter, which has a gentle gradient and a density of one stop of light. The 121M filter has the same gradual gradient as the 121L, but at twice the intensity. This filter requires two stops of compensation. And finally the 121S filter. This filter has twice the intensity of the 121M and the grey runs to three quarters of the filter. This filter requires three stops of compensation.
Filter holder
To attach the supplied Cokin P-series filter holder to your lens, you will need an adapter ring. This is not included, but should be purchased separately.