I don't know about you, but I really like the silky-smooth-waterfall effect,. It's not always that easy to achieve when you want to though. Here are a few tips:
- A good tripod is a must. Don't even try this when hand holding.
- Different shutter speeds will result in different effects, anywhere from slightly blurred to silky smooth. Think about what you want to achieve and use that as the basis of your shutter speed. Usually anywhere between a tenth of a second and a full second works best, but longer speeds can also be tried.
- Waterfalls in mixed lighting tend to work best. Even lighting (sun or shade) tends to result in pictures that lack contrast.
- Look for sections of the falls where the water splits into multiple streams. This creates different surfaces for the light to play against.
- Given a constant acceleration from gravity, the farther water falls the more velocity it will have acquired. To achieve the same effect, pick your shutter speed based on the volume and speed of the water going over the falls — shorter exposures for more water. Keep in mind though that fine spray will fall slower due to air resistance.
- It's better to choose a shutter speed that would result in a slight underexposure rather than risking the shot being overexposed. The brightness of the portions that are lit will build up during the exposure. If it ends up overexposed, you will loose all the texture in the image.
- Even with fine-grained slower-speed slide film, you will sometimes need to use neutral density filters (full frame screw on ones, not graduated) to get a long enough exposure. In a pinch, your polarizer can be used to darken the frame up to 2 stops.
- Above all, experiment, bracket, and have fun.