There are times when you need to have a very long exposure – longer than the maximum (slowest) shutter speed setting a camera provides (typically around 30 seconds). It’s not hard to do –
- Switch your exposure mode to manual
- Adjust the shutter speed past the slowest available (like 30 seconds) – and the word Bulb appears
With the bulb setting, the shutter will remain open for as long as you hold down the shutter release. Note – you may want to get a remote shutter release that’s capable of locking the shutter open otherwise your finger is going to get mighty tired.
Why would you want to do this? Several instances come to mind like –
- Light painting which we covered here and
- Photographing lightning
Why would we use a long exposure to shoot lightning? Have you ever tried to anticipate a lightning bolt’s appearance and snapped the shutter at just the right time? Finding a needle in a haystack might be easier. Here’s a technique for solving that problem –
- It’s best if you can do this indoors through a window – for a variety of reasons. Note – indoor & outdoor lights may ruin the shot.
- Nighttime – during a thunderstorm
- Camera on tripod
- Manual focus at infinity
- Focal length to suit (try a few and see what happens)
- Shutter speed set to Bulb
- Frame a promising area of the sky
- Open the shutter – and wait
- Lightning bolt appears
- Close the shutter; you’re done
- Experiment with ISO, focal length, exposure compensation, framing…
- ISO=200, f/5.6 worked well for me
- If there is lots of brightening of the sky with no bolts, you may want to close & reopen the shutter every minute or so. If you don’t – depending on your settings – the image may end up too bright and the contrast between the sky and the lightning bolt – when it finally appears – will be too low. Again, experiment.