Techniques
LONG EXPOSURE PHOTOGRAPHY
To increase exposure times in daylight a 6-stop or 10-stop ND filter is required. An ND graduated filter is also needed to darken the sky so that it falls within the dynamic range of the camera's sensor. The use of a tripod and remote release is essential.
When using this technique cloud movement will create dramatic effects and water will appear smooth and silky in the final image. Any structure in the composition such as architecture, bridges or rocks remain pin sharp.