What Does the B on My Camera Mean?

After the letters P, S, A and M on the exposure dial, some cameras have another letter, B. This stands for Bulb mode. Other camera models place Bulb in the shutter speed control where it appears after the longest shutter speed the camera can time, usually 30 seconds (30").

The Bulb setting is appropriate for the times you need really long exposures, such as photographing fireworks or the night sky, performing light painting, or when working in any dim environment.

55 seconds, f/8, ISO 100
Light painting

When you set the camera to Bulb mode, the shutter opens when you press the shutter button and stays open until you let go of the shutter button. It gets its name from the early days of photography when some cameras had a pneumatic shutter release with a rubber bulb on the end. As long as the photographer squeezed the bulb, the shutter stayed open.

Camera set to Bulb (B) exposure mode

On today's digital cameras, keeping your finger on the shutter button for exposures longer than half a minute is bound to create camera movement and a blurry image. So you need some accessories to make the most of the Bulb setting.

First, you need a remote shutter release, which is a "shutter button on a string." One end attaches to a port on the side of the camera. The other end has a shutter button to trigger the exposure. To hold the shutter open in Bulb mode, you press and slide the button forward until it stops. A red outline warns you the shutter is locked open. To close the shutter, you press and slide the button back.

Wired remote shutter release in the locked position

You can use either a wireless or wired release; I prefer the wired models because they don't need batteries. These shutter releases are camera-model specific, so be sure the one you buy works with your camera.

Wired remote shutter release plugged into camera

Second, you need a way to measure the longer exposure time. You can set a timer on your smart phone, observe a sweep second-hand on a wrist watch, or even count off the seconds to yourself (one-thousand one, one-thousand two, etc.).

Finally, because you are making a very long exposure, your camera needs to be completely still. A tripod is the best way to accomplish this.

Tripod-mounted camera with attached shutter release
in the locked position.

You can see more examples of photos taken with Bulb mode in this post and examples of fireworks pictures done with Bulb mode here.

Learn more about your camera controls in my digital photography classes in Missoula, Montana. Click here for a list of upcoming courses and to register.