The best way to click long exposures is to mount an ND filter over the front element of your lens. What if you do not have one?
ND filter (neutral-density filter) reduces the amount of light entering the camera, through the lens. This allows you to capture long exposure photos which otherwise can be challenging. The ND filter also allows you to capture long exposures while the aperture is wide open.
Do you know you can capture long exposures without using the ND filter and manage to get well-exposed photos? Well, I am not saying that the points I am going to discuss will eliminate the use of ND filter, but it can surely allow you to slow down the shutter speed of your camera to capture long exposures.
In order to get the slowest possible shutter speed, you should always use the minimum ISO sensitivity number available in your camera. In the majority of cameras, the lowest ISO is 100.
While clicking landscapes and cityscapes, the ideal aperture value range is f/11 – f/16 in order to get desired depth of field and sharpness. The moment you increase the aperture value on your camera, the shutter speed reduces in order to let in more light. This is the trick.
In order to slow down the shutter speed, maintaining the correct exposure, try and increase the aperture value on your camera.
E.g.: If clicking at f/8 is giving your the shutter speed of 1/20 second, increase the aperture value to f/11 (1 stop) will reduce the shutter speed to 1/10 second (1 stop).
This tip can work best for clicking photos during sunrise and sunset, as the light is not that harsh.
When your camera is clicking photos at a slow shutter speed, using a steady tripod is a must. Make sure that the VR/IS switch is turned-off on your lens to minimize the camera shake. To further reduce the camera shake, turn-on the mirror lock-up feature in your camera.
Here is one of the lone exposure shot I clicked recently without the use of ND filter. To give the milky flow effect of water, i had to use a slow shutter speed.
Shutter speed: 10 sec
Hope this helps you click long exposure shots with the help of ND filter. But the ND filter has its own benefits.