Long exposure images with smooth water and streaking clouds are very popular at the moment, but if you’ve ever tried to shoot one during the day, especially in sunshine, you’ve probably discovered that even at its lowest sensitivity (ISO) setting and with a small aperture, it’s not possible to get the exposure that you’re looking for.
The secret is to use a neutral density (ND) filter to cut down the amount of light that enters your lens and reaches your camera’s sensor. This means that even though the light is bright, you can shoot with a long exposure.
ND filters come in a variety of strengths, but 10EV and 6EV filters like the Lee Filters Big Stopper and Little Stopper are the most popular. A 10EV filter increases the exposure by 1024x while a 6EV filter extends it by 960x.
Using a dense ND filter
Because 10EV and 6EV filters cut out so much light it’s often best to set-up you camera, compose the shot and focus on the subject before the filter is attached to the lens. When you’ve got the scene in sharp focus it’s a good idea to switch to manual focus to prevent the camera from making adjustments when the filter is in place.
Next, without the filter in place, set the camera to manual exposure mode, select the aperture that you want to use and measure the shutter speed that’s required. You need to multiply this value by 1024 or 960 to get the exposure time with the filter in place. If you don’t fancy doing the maths, there are smartphone apps available such as the free Lee Filters Big Stopper app that do the work for you.
The next step is to mount the filter on the end of the lens and set the exposure time. If this is over 30 seconds in length, most cameras will need to be set to Bulb mode. A tripod is essential to keep your camera stock-still during the exposure and a remote release that enables you to trip the shutter and lock it open without touching the camera is advisable.
In Bulb mode you need to press and lock the shutter open with the remote and time the exposure using a watch or your smartphone - the Lee Filters’ app can help with this as well. At the end of the exposure time, simply press and unlock the remote release to close the shutter.
If your camera’s long exposure noise reduction system is activated (we recommend that it is) it will take a second ‘dark’ exposure of the same duration as the imaging one to find where the noise is and extract it from your image. This means that you’ll have to wait a little while before you see the captured image on the back of the camera.
The last step is to check the image to verify that the exposure and that the degree of blur is what you want. If you’d like more blur, decrease the size of the aperture by one stop to double the exposure time.