If you’ve ever played with your camera’s shutter speed, you may have seen the word ‘BULB’ appear on your LCD screen. But what does this mean and what does it do? BULB mode allows the photographer to use infinitely slow shutter speeds, offering the ability to work with very long exposures. The slowest built-in shutter speed on most cameras is 30 seconds, but the BULB mode lets you go beyond that and keep the shutter open for as long as you like. In simple terms, when taking a picture in BULB mode, the camera will keep taking a picture until your finger comes off the button.
Why Is It Called BULB?
The term ‘BULB’ mode comes from the days of old-school film cameras, which used a pneumatic valve bulb to control the shutter speed during very long exposures. When the bulb was pressed, it sent a blast of air to the camera, which kept the shutter open. Once the pressure on the bulb was released, the shutter would close. The disadvantage here was that in order for the shutter to remain open, constant pressure had to be applied to the bulb. So imagine doing an exposure of 10 minutes or longer – it would have gotten tiresome. Luckily, the modern BULB function automatically locks the shutter open until the release button is pressed for a second time, without having to hold your finger on the button.
How To Use BULB Mode
When shooting in BULB mode, your camera is working with very long exposures, and because of this there are two pieces of equipment that are crucial to bring along if you want to achieve crisp images. Aside from your camera (of course), you will need a tripod and a remote or cable release. The tripod will stop your camera moving during the exposure, as there is no way that you can hand hold a camera in BULB mode without getting severe camera shake. A remote or cable release will allow you to start and stop the exposure without touching the camera. This is important because even a tiny movement or shift in the camera (such as using your finger to press the shutter release button) will create blur in your image.
To access the BULB function, you need to have control over your shutter speed, so using Auto mode is not an option. Manual mode works best, as you also have control over the other settings such as ISO and aperture. To find BULB, make your camera’s shutter speed as slow as it will go. Most cameras will show 30 seconds as the slowest timed speed, and the next option after that is BULB mode. In BULB, you need to press the shutter release once to open the shutter, and then again when you want to close it. Many people like to use an external timer when shooting in BULB, so they can keep track of how long the exposure is. A stopwatch or a timer on your phone will work well for this. It’s useful to know how long your shutter speed is so that you can replicate the exposure for other shots, or make suitable adjustments, rather than just wildly guessing how long you should keep the shutter open.
When To Use BULB Mode
BULB mode is mostly used for night photography, as its main purpose it to allow photographers to use long exposures longer than 30 seconds. This includes shooting things such as star trails, light trails and when light painting (with sparklers or a torch), where the shutter needs to be open for several minutes (or sometimes hours).
However, there are lots of other ways that you can use the BULB function to push your creative skills:
Image taken by Chris Lundberg
Lightning: You may think that a fast shutter speed is needed to capture lighting (as it strikes quickly), but using BULB mode to capture it gives you a much higher chance of snapping that bolt of electricity. Just open the shutter and wait for the lighting to strike, then you can’t miss it! The advantage to using BULB mode is that you can close the shutter as soon as you need to, rather than capturing multiple strikes of lightning all within the same frame.
Fireworks: Bulb mode allows you to capture the entire movement of fireworks, colours included. Just like with lightning, you can snap fireworks separately without each burst being included all within one photo.
Image taken by Tom Bricker
Fog and clouds: Movement in clouds and fog can be captured beautifully using BULB mode, as they slowly rise, fall and shift. Taking several long exposures using different exposure times and comparing them will show you how varied your results can be.