To try to avoid having too much light when you have long shutter speeds, one technique to keep in mind is adjusting your camera’s aperture to make it smaller. This is the process of changing the size of the hole that the light comes in through. Another technique is decreasing your ISO. A lower ISO will make the sensor less sensitive. Trying a neutral density filter is also another technique which decreases the amount of light passing through your lens, which allows you to use a slower shutter speed. The two last techniques to use are slow sync flash, which adds flash to longer shutter speeds so that some subjects in the photo are blurry and some are frozen, and panning, which is following a moving subject with your camera.