Light Leaks in Images
Weird bands of color will appear in the image. They are also referred to as ‘light streaks’ because that’s what they look like – weird random bands of light. They could be horizontal as well as vertical. They are particularly exasperating for a landscape photographer, who may have had set his camera to shoot a slow shutter speed time-lapse and after several hours of shooting gets thousands of photos with light streaks on them. A truly annoying and frustrating experience!
Why Light Leaks Affect Long Exposures More Than Normal Exposures
When you make long exposures, there is that much more time for even a small amount of light leak to create strong streaks in the image. Normal exposures lasting for only a fraction of a second wouldn’t be enough for light leakage to really affect an image.
Since photographers normally shoot long exposure images using ND filters, these filters, or sometimes even lenses are usually blamed for this problem (yes, some lenses can potentially create light leaks as well, but that’s rare and typically happens on very long exposures).