Using your camera to create long exposures for night photography
Silky Ocean Water at Sunset – Little Compton, Rhode Island
A recent discussion in an online photography forum has gotten me thinking. The original discussion was about long exposure and night photography ,and what equipment you used when creating successful long exposures. I started to think about not just the equipment I used, but also the techniques that I used that help make the process of night photography easier and more enjoyable. The more I thought about, the more I thought about writing this article and sharing that information with you!
After the sun sets below the horizon, many photographers will pack up their equipment and head on home. To me this is one of the most exciting times to own a camera. Whether you are in the city or out in the country, the night is full of life. The moon, the stars, city lights and buildings all make for great night photography. Getting those great photos is not hard – you just need to use a few tools and apply a little knowledge and you will be well on your way.
In the simplest definition, photography is the recording of light over time. The light falls on a subject, bounces off of the subject and is recorded by the camera sensor. Night photography is no exception, there is just less light to record. When photographing at night we often leave the shutter open for several minutes at a time in order for the camera to record enough light to successfully capture the subject. Depending on how much light is in the scene minutes might not even be long enough!
The very first obstacle to overcome is keeping the camera still. During the several minutes that it can take to photograph the scene it is absolutely critical that the camera stays perfectly still. Any movement of the camera will result in photographs that will appear “soft”, or blurry. The edges of subjects in the scene will look fuzzy and unclear. To get crisp, sharp subjects the thing that we to do first is to lock your camera down. This means a good, solid tripod.
The second piece of equipment needed for night photography is a way to trigger the shutter. We all know that to take a photo we simply press and release the shutter button on the camera. We can still do that, but there are two catches to this. The first is that anytime you touch the camera we are going to move the camera, even if it is only slightly. A remote cable release is simply a cable between 2 and 3 feet long that plugs into the side of the camera and has a shutter button at the end of the cable. You hold the cable and push the button, triggering the shutter without actually touching the camera.
There is one thing that we need to understand about most modern dSLR cameras. They have a very wide, but not infinite, range of shutter speeds. Most offer a range of about 1/8,000 up to 30 seconds for exposure time selections. Wait a minute, how do we take a photo with an exposure time of several minutes if the camera has 30 seconds as the longest shutter speed? Enter bulb mode! Bulb is a shutter speed setting that allows the shutter to be open as long as the photographer wishes. The name comes from the days where the shutter was pneumatically actuated by squeezing a bulb to open the shutter and then releasing the bulb to close the shutter. With modern cameras, the shutter release cable acts as the bulb. Instead of holding the button in, there is a locking mechanism that holds the button in until you unlock it to release and close the shutter. This allows you to take a photograph of virtually any length that you would like!
Now if you really want to take your photography up a notch, you can get a cable release that is an intervalometer. An innerwhatchamacallit? An intervalometer is simply a device that counts time. In photography, this is a fancy cable release that you can program how long you want the exposure to be. This can come in REALLY handy! Instead of keeping track of the exposure length yourself, this tool will do it for you.
While not necessarily related to night photography, these little gadgets also do a whole lot more! You can program it to take a number of photographs, of a programmed exposure length with a programmed time in between. This can make time lapse photography a breeze! Much pricier then a standard cable release, but it also provides many more features. It is just up to you to decide if you need those features!
Now at the beginning of this article, I told you that I was going to talk about equipment and techniques to make night photography easier. I have talked about the gear, now lets spend some time on the techniques that I like to use.
Lets start with a technique to help you determine how long to your exposure needs to be. When working in Bulb mode you are creating the exposure on your own. The cameras internal exposure meter goes right out the window! So how do you know how long to keep your shutter open? Do you simply take a guess, and then look at the photo on the LCD and then try to guess how much more or less time you need? You could, but that is a pretty inefficient and tedious approach. This is a time that I really like to take advantage of the high ISO settings that are available on today’s dSLR cameras. By cranking my ISO up to 3200 or even higher I can switch back to manual mode and allow the meter to guide me.
To help understand this, lets walk thorough an actual example. One night at a beach this summer I was shooting well past sunset. There were some interesting rocks along the shore that I wanted to photograph. With the camera in Manual Mode, I set an Aperture of f/8.0 and my ISO to 3200. The meter indicated that a Shutter Speed of 4 seconds would give me a correct exposure. I took a photo, and looked at the result on the LCD on the back of the camera. The Histogram told me that the exposure was correct. Is this what I want to use for my final image? No, I want to shoot with an ISO as low as possible to help reduce noise at image creation time. But what I do have now is a baseline that I can use to calculate what my exposure time needs to be when I change my ISO back to 100. Keeping the Aperture at f/8.0, here are the equivalent exposure settings that I can use:
- ISO =3200, Shutter Speed = 4 seconds
- ISO =1600, Shutter Speed = 8 seconds
- ISO =800, Shutter Speed = 15 seconds
- ISO =400, Shutter Speed = 30 seconds
- ISO =200, Shutter Speed = 60 seconds
- ISO = 100, Shutter Speed = 120 seconds
This tells me that in order to get the same exposure at ISO 100 that I have at ISO 3200 I will need to change my shutter speed to 120 seconds. Now I can switch back into Bulb mode, lower my ISO to 100 and leave the shutter open for 120 seconds in order to create a proper exposure! No more guesswork, no more frustration! Precise, accurate long exposure shots that are right on the money!
There is a second advantage to this method. These high ISO, quick shutter speed photos are a fantastic aid when composing an image! By cranking my ISO up to 3200 I can now take a photo in a short amount of time (relatively speaking), and evaluate the composition on the LCD . This allows me to move the camera position and adjust the focal length to really nail down the composition. There is nothing worse then waiting 2 minutes to see the photograph on the LCD and then realizing that there is a something wrong with the composition, or something in the frame that you did not see.
Just like any skill, it will take a little bit of practice to become really comfortable with this approach. The great thing is that you don’t necessarily need to go out into the dead of night to practice. Set your camera up in a dimly lit room and you can run through this exercise right in the comfort of you own home. And believe me, you will be glad that you tried this out BEFORE you are out at a location in the dark trying to figure it out in the dark of night.
I hope that this article helps you to get out and create the long exposure shots that you are looking for!