Bulb Mode and Long Exposure: Using the Shutter Timer

What is bulb mode

Bulb mode is a shutter setting that keeps the shutter open for as long as the shutter button is held down. It exists because every camera has a maximum timed shutter speed, commonly 30 seconds, after which the built-in timer stops. Bulb mode bypasses that limit so you can expose for as long as you need, whether that is two minutes or twenty.

The name comes from early cameras that used a rubber bulb attached to an air tube to trigger the shutter remotely. Pressing the bulb opened the shutter, and releasing it closed the shutter, giving photographers a hands-free way to hold an exposure. Today the same principle is implemented electronically in nearly every interchangeable-lens camera and most advanced compacts. You select Bulb on the mode dial or within the shooting menu, and the camera holds the shutter open for the entire time the button is pressed, and for a short moment after you release it to allow the shutter to actually close.

In addition to bulb mode, many cameras offer a related setting often labeled Time mode. Time mode opens the shutter on the first press and closes it on the second press, so you do not need to hold the button down. That is convenient for very long exposures where holding a button for several minutes would introduce finger fatigue and the risk of nudging the camera.

For a deeper look at how shutter speed interacts with aperture and ISO, see our guide on the exposure triangle.

How to set bulb mode on your camera

The steps differ slightly between camera brands, but the general workflow is consistent. Start by placing the camera in Manual exposure mode. Then rotate the main command dial until the shutter speed display shows the word Bulb, sometimes abbreviated as B. On many cameras, you can also set the mode dial directly to the Bulb position. If you cannot find it, consult the manual that ships with the camera, since the location varies by brand and model.

Once bulb mode is active, the camera does not meter for a specific duration. It simply opens the shutter when you press the release and closes it when you press again or let go, depending on whether you are using bulb mode proper or time mode. You will need to determine the exposure length yourself, typically by taking a test shot, checking the histogram, and adjusting. The histogram and zebra guide explains how to read the result.

Some cameras offer a feature called long exposure noise reduction, which is worth enabling for exposures longer than a few seconds. After the main exposure, the camera takes a second dark frame of the same duration and subtracts hot pixels and noise from the final image. This doubles the time needed per shot, but it visibly improves the result. You can read more in the long exposure noise reduction article, and see how the ISO setting influences noise in the ISO sensitivity guide.

Remote releases and exposure timers

Pressing the shutter button by hand, even gently, introduces a small amount of camera movement that becomes visible at multi-second exposures. A tripod alone does not fully solve that. You also need a way to trigger the shutter without touching the camera. The simplest solution is a wired remote release that plugs into the camera body. With a remote, you can lock the shutter button open and walk away while the exposure runs. Some models also support the camera manufacturer's wireless smartphone app, which lets you trigger the shutter and view the scene on your phone.

An intervalometer is a more advanced remote that can trigger the shutter at set intervals for a set number of frames. It is the standard tool for time-lapses and for star trail photography where the photographer wants to capture many exposures and merge them later. Many modern cameras have a built-in intervalometer in the menu, which avoids buying a separate accessory. For a project that combines long exposures with time-lapses, read the intervalometer and time-lapse guide.

A remote release also frees the photographer to cover the viewfinder eyepiece if light can leak in through it, and to watch the scene rather than stand exactly at the camera. For night shoots, where you might be away from the camera operating a light source for light painting, a remote with a locking mechanism is especially practical.

When to use bulb mode for long exposures

Bulb mode is made for scenes that demand an exposure longer than the camera's standard maximum. The most common cases are night and low-light photography: a dark landscape under a full moon, the Milky Way, or a city skyline at twilight. At night, even with the aperture wide open and the ISO at a moderate value, you often need 30 to 60 seconds or more to capture a scene that the camera meters as almost completely dark.

Water is another classic subject. A several-second exposure smooths a waterfall or ocean waves into a silky mist, and a longer exposure of a lake can make the surface look like still glass. The same idea applies to skies: a 2-minute exposure makes stars appear as short trails instead of points, and a 10-minute exposure extends those trails further. The motion blur at these durations is entirely different from what is possible with a standard 1/60-second shot. To understand how focal length and cropping change the look, see the focal length and angle of view article.

Light painting is a third use. The photographer opens the shutter in bulb mode, walks into the dark scene with a flashlight, and draws shapes in the air or illuminates parts of the subject for a few seconds each. The shutter stays open the whole time, and the light builds up only where it is aimed. You can see the same technique used by photographers working with Leica cameras and lenses, a brand often chosen for its rugged manual controls and precise timers.

Finally, bulb mode is useful for intentionally long exposures in daylight when you are using a neutral density filter strong enough to cut light by many stops, allowing a properly exposed image at a very long shutter speed. This works for photographing busy streets with the people blurred away, or for making crowds disappear from a public square.

Key points to remember

Here are the essential points to keep in mind when you start shooting in bulb mode.

• Use a tripod rated for your camera and lens weight; the tripod mount and stabilization guide explains how to match them.
• Set the camera to Manual mode and select Bulb to reach exposures longer than 30 seconds.
• Trigger the shutter with a remote cable, a wireless app, or an intervalometer to prevent shake.
• Enable long exposure noise reduction for multi-second exposures to remove hot pixels.
• Check the histogram after each test shot and adjust the exposure time based on the result.
• Shoot in raw format to recover highlight and shadow detail that JPEG compression discards.

Which camera for bulb mode work

Any camera with a manual exposure mode supports bulb mode, so you do not need an expensive body to start. The practical differences come down to a few features. A camera with a top rear LCD or a live-view display that shows the shutter speed as B is easier to work with. A body with a wired or wireless remote release makes long exposures more convenient. A camera with good dynamic range holds up better in the deep shadows of a night scene.

Sensor size also matters for night work because larger sensors generally gather more light per pixel. A full-frame camera is the usual recommendation for astrophotography, but an APS-C camera is a good balance between capability and portability. For travelers, a compact with a 1-inch sensor is a far lighter option that still handles a 10-second exposure gracefully. The photographers who shoot cityscapes with bulb mode often pick a 4K-capable camera so they can also capture time-lapse video on the same trip at the same location.

In the table below, find your intended subject and the camera tier that supports it well.

What to pick for your use

Questions

How long can the shutter stay open in bulb mode?

There is no fixed limit. The shutter stays open as long as the shutter button or remote release is held (or as long as the battery supplies power in time mode). Some cameras cap the exposure at 30 minutes or automatically close the shutter when the battery runs low, so check the manual for your specific model.

Is bulb mode bad for the sensor?

No, a long exposure does not damage the sensor. It does increase sensor temperature and that raises the chance of hot pixels in the image. Enabling long exposure noise reduction helps remove them, and simply letting the camera cool between shots prevents buildup.

What is the difference between bulb mode and time mode?

In bulb mode you hold the button down to open the shutter and release it to close. In time mode, you press once to open and press again to close, which is useful for very long exposures. Many cameras offer both options, with different names depending on the maker.

Do I need a special lens for long exposures?

No. Any lens that can be stopped down to a small aperture, such as f/8 or f/11, works for most bulb-mode scenes. For daylight long exposures, you need a strong neutral density filter to cut the light. Some camera makers publish guides to lens filters; for example Nikon's tips and techniques section covers the basics.

Why are my bulb exposures blurry even on a tripod?

The blur is usually caused by pressing the shutter button by hand, by a tripod that is not fully rigid, by wind shaking the camera, or by not using a remote release. Using the camera's self-timer or a remote release solves most cases.

Can I use bulb mode for time-lapse?

Yes, if your camera has a built-in intervalometer or you use an external one. Set the intervalometer to trigger the shutter every few seconds, then merge the frames into a video later.