Creative Field Techniques - Shutter Speed and Super Long Exposures
Recently, I visited Lake Superior in the upper peninsula of Michigan. Using photos shot during my visit, I can demonstrate how the appearance of the water can be altered dramatically by adjusting one setting on the camera, the shutter speed (exposure time). Take a look at the photo below. For this shot, I used a fast shutter speed of 1/60 of a second. This was fast enough to almost freeze the water action without blurring it, but it wasn’t exactly what I was going for.
Instead, I was inspired by the row of pilings and the brooding clouds to create a minimalistic scene using the water and sky as negative space. The water was very agitated and I wanted to smooth it out. To do that, I need a long exposure between 20 to 30 seconds. Wow, that’s quite a difference from 1/60 of a second! A shutter speed of 25 seconds was used for the shot below. That gave enough time for the water movement to blend together and take on a dreamy appearance.
Remember, the more time the shutter is open, the more light that comes in, thus overexposing the scene. In fact, the amount of light coming into the camera is doubled 10 times when going from 1/60 to 25 seconds! That’s a lot of light and normally, the scene would be rendered completely white. So, how did I avoid overexposing the scene? I used a filter in front of my lens. To achieve a shutter speed of 25 seconds, I needed a filter that was dark enough to cut the light in half 10 times (this is called a 10-stop filter and you can see it in the picture below). Simple! Reduce the light with a filter and bring back the same amount of light using a very slow shutter speed. For example, if I had used a filter that cut the light in half three times (3-stop filter), my shutter speed would have been adjusted from 1/60 of a second to 1/8 of a second:
1/60 to 1/30 doubles the light (1 stop)
1/60 to 1/30 to 1/15 doubles the light two times (2 stop)
1/60 to 1/30 to 1/15 to 1/8 doubles the light three times (3 stop)
One last thought -10-stop filters are not cheap, but fortunately they are not always necessary to achieve your creative goals. The Lake Superior shots above were taken at midday when sunlight is at its fullest. It would have been impossible to achieve the long exposure effect without a 10-stop filter. However, shooting just before sunrise or after sunset (during the blue hour) when there is considerably less sunlight will remove the need for a filter. It also helps to set the ISO to its lowest setting (typically 50 or 100) and close the aperture (from f8 to f16 cuts the light in half two times or 2 stops) to help you push that shutter speed into your creative zone.
Check out my previous blog on equipment necessary for long exposure waterscapes.
Here are some links for filter products:
If you lens is not 72mm, search adapter rings for the correct diameter (mm) size.
Here is a link for a 67mm lens adapter
Thanks for looking on and if you are interested in receiving tutorials in Photoshop or individualized workshops in the field, please check out my website and feel free to contact me at email@example.com.