If one wants to shoot long exposures of over 30 seconds then it will be necessary to shoot in bulb mode. What bulb mode allows us to do is to increase the shutter time from 30 seconds to infinity and for this task, we need a steady tripod, an ND filter and a remote release shutter cable. With an ND filter, we will know how much light we are blocking and then it becomes easier to calculate the new shutter speed. For example when composing the initial frame, if the shutter is 1/4 second and aperture is set to f/11, on using a 10 stop ND filter will increase the shutter to 4 minutes 16 seconds. For this we will need a shutter remote.