A layman’s guide to Bulb Mode

In our latest layman’s guide we explain the camera setting that gives you control over the shutter, your camera’s Bulb Mode.

What is Bulb Mode?

It’s a function that allows you to control how long your shutter is open for. It’s not something you’d use regularly, but when you want to make an exposure that lasts longer than 30 seconds, using the Bulb mode is the way to do it.

Where do I find my camera’s Bulb Mode?

That depends on your camera model. On lots of cameras, the Bulb mode can be found on the main command dial and is normally denoted by the capital letter B. However, if your camera doesn’t have this, all is not lost.

Switch the command dial to Manual and work your way down through the shutter speeds, getting slower and slower. There, beyond 30 seconds, you’ll find Bulb!

What is Bulb Mode useful for?

Think of ultra-long exposures with ND filters like the Big Stopper or anything shot in darkness, such as firework images, pictures of traffic trails, astrophotography or painting with light using torches.

In these circumstances, being able to hold the shutter open for as long as you want can be extremely beneficial.

SEE MORE: 8 things you may not know about long exposures, but should

Can you use Bulb Mode for durations of less than 30 seconds?

Yes, of course. If you are painting with light, for example, you may choose to lock the shutter open, work your scene with a torch and close the shutter when you are done – even if that’s less than 30 seconds.

For traffic trails or fireworks, you can keep the shutter open using Bulb but carefully block the lens with a black card, only exposing again when there is a car on the road or a firework in the sky.

So although the shutter is open for longer than 30 seconds the actual time that light is being recorded is a lot less.

What about aperture?

With Bulb, you have to set the aperture manually – f/8 is always a very good starting point!

So I just set the camera to Bulb and then press the shutter button?

No, you will need to use a cable/remote release of some sort that allows you to lock the exposure open for the period you want and then close it when you have finished.

If you use the shutter button then you would have to keep your finger pressed down on it to keep the shutter open.

This would cause movement on the camera, plus it would mean you’d be unable to move!

Obviously you need to work with the camera fixed on a tripod too, in order to minimise any movement or camera shake.

SEE MORE: 3 photos made easier by a tripod and remote release

How do I know that I have got my exposure right?

You don’t always know this, so a certain amount of trial and error is required with those shots where Bulb mode is  being used.

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