As those that have gone on my tours know, I consider a neutral density filter (ND filter for short) mandatory equipment.  In fact, besides the camera, lens, and tripod, it is the only piece of mandatory equipment I have.  I am always preaching about using ND filters when there is water involved.  And there is a lot more water involved in landscape and cityscape photography than you might imagine.

But why?  Does it make that big of a difference?  And couldn’t you just change the camera settings to mimic the effect?   

Let’s take a look.

Photographing Water with Standard Settings (Not Good)

On a recent trip to New York, I found myself in Brooklyn Bridge park next to some old piers.  The spot is fairly famous and I had photographed it before.  It was daylight and a nice day, so there was a lot of light. 

Here was the first shot:

The settings are: shutter speed of 1/800 seconds, aperture of f/4, and an ISO of 100.  I should note that I kept the ISO at 100 for all of these, which is as low as my camera will go, so that will be the same throughout all of these pictures. 

As you can see there are a lot of ripples in the water.  To me, they are a big distraction and I want them to go away.  The way you make them disappear is to slow down the shutter speed in your camera.  When you do that, the water moves during the time you are exposing the shot, such that the water is blurred and the ripples go away.

Slowing Down the Shutter with Exposure Controls (inadequate)

With that in mind, let’s take some steps in that direction.  What we want to do is restrict the amount of light coming into the camera so that we can use a long shutter speed without overexposing the image.  We already have the ISO at its lowest setting, so the only thing we can change to restrict light is the aperture.  We were previously at f/4 (a very wide aperture) so let’s stop that down to f/22, which is the smallest aperture possible.  Here’s what that looks like:

It isn’t much different, is it?  I was only able to use a shutter speed of 1/50.  If I went any slower I would overexpose the image. 

The fact that there was so little change tells us that we need to restrict light further.  The bad news is that we cannot do that using our camera controls.   There is just too much light.  The ISO is already as low as it will go (100) and the aperture is as small as we can make it (f/22).  There’s nowhere left to go using our camera controls.

Adding the Neutral Density Filter (and saving the day)

Enter the neutral density filter.  If you aren’t familiar with them, I have a video about it here

In this case, I used a 10-stop neutral density filter.  After attaching it to the front of the lens, my camera tells me that the shutter speed for a proper exposure should be 25 seconds.  In other words, the neutral density filter has restricted the light allowed into the camera to such an extent that I have to hold the shutter open for 25 seconds for the camera to gather enough light to make a proper exposure. 

Here’s what that picture looks like:

Vastly different, isn’t it?  And to me, a world better.  Gone are the distracting ripples in the water.  Instead, I have a smooth, pleasing background.  It also adds emphasis where I want it – on the skyline and the piers. 

What if you don’t like this look?  I still think you ought to get an ND filter.  You don’t have to take it as far as I did here.  This is a 10-stop filter and they have less dramatic filters, for example at 6-stops (my favorite) and 3-stops.  This puts you in control of the water so you can create whatever effects you want.  As you just saw, you cannot do much with camera controls in the middle of the day.

More Info About Neutral Density Filters

So go get yourself a neutral density filter.  Hopefully this example shows the importance.  Before you do, watch this video about them, which will give you a little more info about them and also tell you some things to look out for as you are deciding.  

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