How do you create light trails?
This is why knowing how to use manual exposure is important. You need to keep your shutter OPEN for a period of time to capture the light. But, as the light is moving the camera can capture ALL the light from the light source (a touch). This creates a trail of light from the path the light moved from and too.
Getting the exposure right is a bit trial and error. To dark increase the ISO or Open up the aperture (smaller f number). Image to dark then decrease the ISO or Close the aperture (higher f number). You may ask why not just change the shutter speed? well, yes you can but that will mean you have to move the light around more slowly and could also result in having to wait longer for the exposure to finish. If you doing light trails on moving vehicles on a road, the time it takes for a car to reach the start point and the end point is calculated. This is you shutter speed, so you don't want to change that or the vehicle could only get half way down the road when the shutter closes. SO its good practice to only change the ISO or aperture.
Checkout the video >> HERE << on how this is done.
