How do I make the water silky in water/beach photography?

Question

I see beautiful photos of beaches or rivers/streams where the water looks like frosted glass...

How is this effect achieved?

Is it a longer exposure?

Answer 1

As others have said, it depends a lot on what kind of effect you want on the water and how much light is available.

What I usually do is decide on how milky I want the water and then find out the time needed to get there. Note that the speed and volume of water impacts the result, so the thinner the stream/flux is the more time you need.

Here is a shot that required six seconds in order to achieve the effect I wanted. Fortunately the scene was under the trees on a heavily cast day and I wanted to use a smaller aperture (8.0 in a Canon compact) resulting in a bigger depth of field, otherwise there would be too much light for the shot:

If you are shooting at night, you may use even longer times, 15 seconds for example, before overexposing the picture:

Note that on such long exposures, if you want someone to be part of the scene, be sure they stand really still. Here again, 15 seconds were used to make sure the water was milky enough:

If, on the other hand, your scene is in plain daylight (by noon, even worse), you will certainly need a powerful ND filter, in order to allow the same 15 seconds. Here two of them were used, an external one with 9 steps and the camera built in, with 3 more steps:

Answer 2

Yup, that's really all there is to it.

But it takes some experimentation in each case, because the way the water moves is always different. So I've got a variable ND filter that I use. It's trial and error until I get an exposure that I like.

It's not necessarily best to just go for the longest exposure possible. If you go for too long, it'll start to look like ice.

I just this morning posted to flickr a photo I took at Kent Falls in CT on Saturday. I think I've got here about the longest exposure possible before it starts to look too "hard". This was 0.7". I did some others as long as 10", and those longer ones were too extreme.

So the variable ND filter is good to dial-in the right amount of freeze. Although I guess you could also get control by changing aperture and ISO, if you didn't have a variable one.

Answer 3

Is it a longer exposure?

Yes.

Use a tripod or rest the camera on a rock to get a steady shot and choose a longer shutter speed (coupled with a smaller aperture if necessary).

Experiment with different shutter speeds to get different effects.

Answer 4

I was experimenting with this recently. Here are some pictures of a small cascade in western Massachussetts last fall.

1/2 second:

1 second:

4 seconds:

Yes, I know some highlights got blown. This was mostly so I'd have a record of different tradeoffs with flowing water. The tradeoffs might be different with a larger waterfall like what Chris showed since the water should be moving faster. Looks like I need to do a bit more experimenting.