Get your gear together.
The perfect long exposure takes practice and understanding of your camera and equipment. For a successful image, you want to avoid any kind of camera shake. “Your tripod is the most important thing. If you don’t have a sturdy tripod and the wind blows and it shakes your camera, it’s going to cause things to get blurry,” says photographer and professor Adam Long. Camera shake can occur when you simply push the shutter button on your camera. Using a shutter release button allows you to set your time and start your exposure without touching the camera.
Using manual mode.
Every camera is different, but DSLR and digital cameras have a manual mode, which allows photographers to choose their own aperture, shutter speed, and ISO. For long exposures, some cameras offer up to a 30-second-long shutter speed. For longer shutter speeds, you’ll need to use the bulb setting (sometimes called bulb mode) to get the right exposure. Using the bulb setting in your camera allows you to keep the shutter open for as long as you hold down the shutter release button.
Understanding aperture and ISO.
Shutter speed, aperture, and ISO are all closely related, and all affect the exposure of your image. When one setting changes, the others need to adjust to counter it. Using a high f-stop number makes the aperture (opening) in your lens very small, limiting the amount of light the sensor of your camera receives. A small aperture means you’ll need a longer shutter speed and exposure time, and you may need to increase your ISO, or light sensitivity. But increasing ISO can increase the graininess of your images.