Shutter speed is the amount of time that you expose your film or your digital sensor to light. So, more light is let through as your shutter speed lengthens.
You may have noticed that the way the Milky Way and other nighttime imagery looks to your naked eye is much different from how it looks in photos. That’s because much of the color and light in the night sky is invisible to us. However, by using longer shutter speeds (and letting in more light), we can expose the light and color that our eyes miss.
Keep in mind that:
- The darker your scene, the longer your shutter speed needs to be for your camera to pick up on all of the details of the scene.
- The need for longer shutter speeds in night photography is one of the reasons that you must use a tripod — shutter speeds over 2-3 seconds make it easier for your photos of stars, planets, and constellations in particular to blur.
- When you’re shooting exceptionally dark scenes or creating stair trails, you’ll need to shoot at a shutter speed longer than the ones your camera provides. Use a remote shutter release to shoot at shutter speeds greater than 30 seconds or so. You’ll need shutter speeds as long as 3-4 minutes for many nighttime landscapes, for example.
ISO Camera Settings
Understanding ISO is crucial for long exposure photography, as ISO determines the sensitivity of your camera’s sensor to light.
- The less light you have, the higher you must set your ISO.
- The more light you have available (i.e., from the sun or from artificial light), the lower you set your ISO.
Keep in mind that a higher ISO means a higher chance of noise (grain or pixilation). So, generally, you’ll want to keep your ISO as low as you can by adjusting your aperture and shutter speed before touching your ISO.
“Noise” like this is often the result of a too-high ISO setting. Photo by josef.stuefer