Because the light is low at that time, the sensor needs to be exposed for longer.
However this technique can also be used during daylight to add special effects to your images. It can capture and blur movement in clouds and water. Choppy seas or lakes will turn smooth, calm and sometimes with an almost milky appearance. Deeper colours will be captured in sunsets. Traffic headlights will become light trails.
The photo above demonstrates some of the uses of this effect. The clouds assume an almost painterly feel, the waves in the lake have been blurred and appear calm and peaceful. However the boat remains sharp.
It can also create a dream-like fantasy environment in your photographs.
To take a long exposure photo there are a few prerequisites. First and foremost, you must use a tripod. Without this you images will be a blurry mess.
You need to choose an appropriate subject. Moving objects such as rushing water, waves, clouds or traffic headlights all work well.
You will need to experiment. Start with an exposure of a few seconds and take it from there. There should be a setting in your camera called "Bulb" or "B". This setting lets you keep the shutter open as long as you want.
Use a remote control to trip the shutter. If you press the button, it may shake the camera and cause unwanted blur. Use a small aperture and the minimum ISO to get the best results.
During the day you will need filters to hold back the light. Without them, your photos will be over exposed and ruined. Think of long exposure photography as the same amount of light getting into your camera but over a longer period of time.
I use various filters. Circular Polarisers and Graduated Neutral Density filters are needed. I also use an ND110 or Big Stopper filter. With this you need to set up everything first and then attach the ND110 to your lens. It's just not possible to see through the viewfinder when this lens is attached. This allow exposures of many minutes long.
Yes, you will need patience.
I shoot RAW and apply noise reduction, either in camera or afterwards in ACR because the longer the exposure is, the more noise you will get.
In the above photo of a boat moored at Beltra Lough in Glenisland, a 30 second exposure sharply captured the still elements while blurring the water into a mist-like appearance. The clouds look like they were painted in afterwards.
I feel that rather than capture an image, this effect captured an amount of time. As a result, it creates movement and gives an almost 3 dimensional feel in the photo.
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