Long Exposure Photography Tutorial (How to Achieve a Smooth Effect for Motion)
Long exposure is a popular genre of photography that provides silky smooth, or smearing affect in photos. Most noticeable as a technique when capturing images around water, it allows the water to be rendered into a milky blurred image while the rest of the static parts of the photo are sharp and crisp.
The cool thing about this technique is that as impressive as it may look, it is by no means as difficult as one might think. In fact, if you consider the "wow factor" of impressing family and friends, this is about as good and easy as it gets. They will be impressed at your photography genius while you smile at how simple it really was.
Long Exposure in Daylight
There are three things you can control in photography; ISO, aperture and shutter speed. What you cannot control is the sun.
Using a neutral density filter will allow only a small amount of the light into the camera. Think of the ND filter as sunglasses for the camera. At least that's what all the other tutorials have said it was so I'll go with that analogy.
There are different ND filters that let in various amounts of light. Each ND filter 'stop' reduces light into the camera by a factor of 2. So if you want 3 stops of exposure then you'd use a ND8.
For my use a 10-stop neutral density filter is all I need. It covers a lot of exposure ground. If you want silky smooth clouds rushing against a sky or a milky waterfall then in most cases all you will need is a 10-stop neutral density filter for long exposures in daylight.
In order to get the motion blur of a photograph you will have to expose the photo for multiple seconds. Doing this in the middle of the day, as one might imagine, would create a highly blown out image no matter how little sun was out. In fact, the image would basically be all white as it would be completely exposed.
So how is this over-exposure solved?
Well, let's say I want a 1/30th second shutter speed for my photo. Using a 10-stop neutral density filter will require 30 seconds for the shot to be exposed. Plenty of time for the movement to blur. A 1/15th shutter speed will take 60 seconds.
The math can get complicated so fortunately there is little reason to be in the field figuring all this out. Just go to your favorite app store and download a neutral density calculator. The Long Exposure Calculator is free.
Avoid Camera Shake for Long Exposures
Whatever you are taking a photo of whether it's moving clouds or the movement of the water over a waterfall you will necessarily require a tripod or steady base to operate from. For up to 30 seconds the shutter on the camera will be open to allow the light to come through the filter. Any shake of the camera will be recorded onto your image.
So you though the whole point was to have a smeared blurred look. It is. But the image only looks silky smooth if there 1) is movement in the photo to record and 2) if the non moving parts are perfectly static.
The bottom line is you have to use a sturdy tripod.
Additionally a remote way of operating the camera must be used. For instance using the 'BULB' mode will allow the shutter to remain open as long as the shutter release is held. Unfortunately you don't want to hold the button for long as it will inevitably add shake to the photo.
A simple remote shutter release solves the problem. They can be as fancy or simple as you like but all you really need is a way to press the shutter and release the shutter off camera during those 30+ seconds of exposure.
Focus Before Adding the Neutral Density Filter
When you snap that 10-stop neutral density on your lens you will notice that you cannot see through it focus as normal. While that may be an annoyance remember that you are setting up for a 30-second shot. You can slow down and take your time to compose the shot and focus.
Before the neutral density filter is placed on the lens focus the shot. It's just that easy.
Composition of Long Exposure
If there is no movement then long exposure is mostly pointless. There needs to be something like clouds, water, cars or even people moving to add the blur that is desired.
All the typical methods of composition are at play during long exposures. Finding interesting places or things to photograph and composing into the rule of thirds or balanced elements or against an interesting pattern are still worth thinking about.
There are really two elements to a long exposure photograph and that is the part that is moving and the part that is static. You want to figure out how to make each as interesting to the eye as possible.
I love the look of motion blur from long exposure photography. It may take a bit of extra planing and new piece of kit to get the shot you want, but the results can be quite striking.
Motion blur will not cover up bad photography techniques but in this instance long exposure can enhance a blurred photo. Creating a silky smooth photo of motion is fun photography. I hope you give it a try.