Techniques to avoid having too much light when using long shutter speeds: Using small apertures: because longer shutter speeds gives more time for light to get in a way to limit the amount of light that gets in can be by setting a small aperture (a smaller hole for the light to come through). Decreasing ISO: additionally, to limit the amount of light that gets in with longer shutter speeds you can lower your ISO, which makes the camera less sensitive to light. Neutral Density Filter: finally in order to limit the light that gets in when using longer shutter speeds one can use a filter that cuts down on some of the light that gets in through the lens.