It is critical to have an understanding of long exposure photography if you are intending to shoot at nighttime. While flash photography is common in low light for ease-of-use, long exposure allows you more control and better results.
Long exposure is the act of leaving the shutter open for longer than a typical photo, say for 1 second, 5 seconds, 10 seconds, 30 seconds, or even longer. The duration depends on the available light and the intended brightness of the photo.
Imagine you are camping out in the wilderness with your DSLR and you want to photograph a nearby scene with a lake and a mountain in the distance. A flash will not help you in this situation; use a long exposure.
First things first
You will need is a tripod or a solid spot to lay your camera. Then, set your camera on a timer setting, so that your camera will settle after you press the shutter button and before it takes the photo. Even better, acquire a wireless shutter release to take the photo without touching the camera.
Next, you’ll want to get your focus correct. For most landscapes or night sky shots, you are safe focusing to infinity on your lens. Move your manual focus element to the “infinity” symbol on the focusing display, if your lens supports it. You want to focus your camera as far out as possible because the subjects are far away. For the more dedicated photographers, set up your camera during the day and acquire the focus, then leave the camera still until nighttime.
Now, for the camera settings, set your desired f-stop, which will often be somewhere between f8 and f22, depending on the available light. The higher your f-stop, the longer you can keep the shutter open without overexposure.
Extra tip: specifically for photographing starry nights, use a lower f-stop paired with a faster shutter speed (such as f2.8 and 1/250 shutter). A slow shutter speed will blur the stars, which is sometimes ideal if you want “star trails.”
Trial and error
As with many forms of photography, trial and error is king. You will undoubtedly need to readjust your camera settings before you can get an ideal shot. Just have fun!