Long Exposures

Let me hit you with some knowledge.

Long exposure is another way of saying “keeping the shutter open for a long time”. This can be done for a few reasons – to compensate for low available light, as one of a many exposures for bracketing, or to capture the idea of motion on film…errr….sensor. Let’s look at all of these briefly, shall we?

Most DSLR cameras give us the ability to control how much light hits the camera’s sensor. We can do this by adjusting the aperture (size of the opening through which the light travels), or time value/length of exposure (the length of time the aforementioned opening stays open). The aperture size and length of time the shutter remains open will help determine the overall exposure of the image captured.

For example, this image was taken with an f/1.8, 50mm lens. The only available light was a street lamp on the other side of the road, diagonally across from the old abandoned gas station. Although this image was shot in RAW, I did not make any adjustments to the exposure while editing. The only thing I’ve done to this image is sharpen and reduce the vibrance in LR, as the original had a strong yellow cast from the lamp light. Despite being taken right around 9pm at night and being shot at 100 ISO, the wide open aperture and long exposure gave me plenty of data in the final image.  (See the final edit of this photo here.)

Settings: f/1.8, 8 seconds

The next scenario in which you might need a long exposure is when bracketing, something generally done when shooting for HDR. The short version – HDR is a high dynamic range image that is the product of several exposures of the same scene run through an algorithm that pulls the best data out of each and creates a composite final image. (Phew! Mouthful! And confusing. You can read more about that here.)

Lost in the Woods

The above photo is an example of an HDR image.  When I bracket exposures for an eventual HDR image, I use the same aperture, focal length, focus, etc for the entire series of exposures. The variable was the time length.

The smaller time value lets in less light to under-expose the scene, there will always be one standard exposure and at least one longer time value to over-expose the image.

Standard Exposure – f/22, 6 seconds

Over-exposed – f/22, 30 seconds

(The above two images were shot on a tripod to keep the camera stable and the images lined up while the shutter was open.)

The final scenario – one with infinite creative possibilities – is using a camera to capture the idea of motion, generally done by following the motion of an object within the frame. For example, the water in above photos is soft, because it moved while the shutter was open.

Main Street Diner

In this photo, the cars long since passed through the scene, but camera captured the trail of the tail lights as they moved through the frame. It was created by putting the image on a tripod, locking my focus and (using a timer to allow the camera vibrations to dissipate) opening the shutter for a long exposure.

Every camera is a little different, so you may have to look through your manual to learn how to adjust your time values. For Canon DSLR users, setting your camera to “TV” (time value) lets you set the time (and the camera will automatically compensate the aperture for correct exposure). Setting your Canon DSLR camera to “AV” in low light (to control your depth of field and the degree of sharpness of the image) will generally end up with a long exposure as well.

For a Nikon DSLR, you adjust the time value by turning the dial to “S” (shutter priority). The aperture is adjusted by turning the dial to “A” (aperture priority).

If you are confident in the philosophy behind each setting, we recommend taking the next step – shot in manual where you can control both! Eventually, you will find the ability to control both allows you to both fine tune your exposures and create more consistent images.

However you get to it, the key to this collaboration is to have a long exposure. Practicing this technique will also inherently teach you about the other settings within your camera, as aperture settings work in concert with time value, and adjusting one will affect the other.

These above examples are just a few of the many, many things you can accomplish with a long exposure image. Certainly, while Nick and I are happy to continue to give examples and inspiration, we are most excited about seeing you express yourselves creatively! We want to see what you do with this technique.

Show us what you can do, friends!