[/caption] Several people have asked me how I created images such as this one of Khounagsi waterfall, about 30km from Luang Prabang. How did I get such a silky effect to the water? What did I do in Photoshop? Well the answer to the latter question is nothing. This image has never been near Photoshop. The simple answer to the first question is, with a tripod and it's very simple to do. You could achieve this without a tripod, but you'd need to find some way of keeping your camera completely steady for a few seconds. The secret is to use a long enough exposure to smooth out the appearance of water - as the water flows over the falls in an irregular pattern, if you use a long enough exposure then these irregularities are layered thus producing a smooth, silky feel to the water. This exposure was made at F16 for 1 second.
Using a similar technique, I shot this image of worshippers departing from the Holysee service in the city of Tay Ninh, Vietnam. Camera mounted on a tripod and shutter triggered with a cable release to prevent any kind of camera shake. The exposure here was 4 seconds at F9
The secret is to take your camera off Auto, and head for either Shutter Priority or full Manual (Aperture Priority will do, but you're setting your aperture to get the shutter speed you need). In Shutter priority (S on Nikon, Tv on Canon), you want to dial in a shutter speed that will blur the movement appropriately. So anything from a couple of seconds upwards will suffice depending on the level of blur you want to create.
Now for the more advanced, if your scene is brightly lit your camera may end up stopping down to F22 or beyond, or if you're shooting in broad daylight your camera may not even let you have a slow enough shutter speed to create the necessary effect. If you do end up with a very narrow aperture then you'll have to bear in mind that this may not produce a completely tack sharp image (most modern DSLR lenses produce their sharpest images at 2-3 stops in from their widest setting). So this is where Neutral Density filters come in. These are essentially darkened pieces of glass that will reduce the amount of light hitting your sensor, thus allowing you a slower shutter speed, whilst still achieving a decent aperture. The Singh-Ray vari-ND is my variable Neutral Density filter of choice, but there are plenty others out there.