I enjoy long exposure photography. The appeal of those silky smooth, milky photos of movement, I think, looks pretty amazing. The interesting thing is that despite it looking like it takes an incredible amount of technical knowledge to create such artistic masterpieces it is rather easy to accomplish. In fact, I think that for a “wow” factor and impressing family and friends this technique gives the most bang for the buck.
This technique is typically most notable with milky water features, smoothing cloud cover and long streaks of solid light in traffic scenes. Of course there are other neat things you can do with long exposure like disappear people out of a vacation shot. But for this post I am going to cover long exposure photography in daylight.
There are three things that a photographer can control with their camera: aperture, ISO and shutter speed. The one thing that can’t be controlled is the sun. If you were to try to capture, say, 30 seconds of a waterfall in order to blur the water movement then even if all your settings were correct you would simply end up with an over-exposed photo that would likely be solid white.
Which Neutral Density Filters to Use?
How do you correct for this over-exposure? A neutral density filter to the rescue. Like every other photography blog discussing long exposure I too will suggest that a ND filter is like “sunglasses for your camera”.
There are a staggering number of ND filters. ND2, ND4, ND8, etc., etc. Each ‘stop’ of an ND filter reduces the amount of light entering the camera by a factor of 2.
So 1 stop is equal to a ND2 filter. A 4 stop filter is equal to a ND16 filter. My favorite and almost 100% used filter is a 10 stop filter. A whopping ND1024.
How Long is the Shutter Speed?
In order to get the motion blur of a photograph you will have to expose the photo for multiple seconds. How do you know how long? The easiest thing to do is grab a ND filter calculator from your favorite app store. It makes it extremely easy to figure based on the ND filter used and the shutter setting you prefer, how long to keep the shutter open. The Long Exposure Calculator is free.
The hard way is math. For example if you take a test shot and you use a shutter speed of 1/30th of a second, adding 10 stops will require a shutter speed of approximately 30 seconds. Shooting at 1/60th of a second and adding 10 stops will require a shutter speed of 15 seconds. Seriously, a calculator is much easier to use.
Workflow of Long Exposure Photography
Putting all this together this is how I execute long exposure photography in daylight:
- I slap my camera on a tripod. You cannot adequately do long exposure photography without a tripod.
- Compose the image and lock down the focus. You will not be able to focus on your intended subject when you screw on the filter. I use manual focus to get things the way I want it.
- Take a test shot and record the shutter speed.
- Calculate how long the exposure must be in relation to your filter, in my case a 10 stop filter, and the shutter speed of the test shot.
- Screw the filter on.
- Take the shot with one caveat. You want to avoid camera shake. Either set a 2 second delay when you press the shutter button, assuming it’s under 30 seconds. Or, if the exposure is over 30 seconds then you have to change to ‘bulb’ mode and then you’ll need some kind of shutter release device.
With a little practice I think you will find long exposure photography to be quite rewarding and enjoyable. I prefer using a 10 stop neutral density filter but there are plenty of other options available to generate different movement shots in photos.