Heuston Station departure board shows the 0735 Galway train with connections to Mayo. I was heading to Foxford, one of the smallest stations on the route. I used a slow shutter speed to capture the LED sign. My exposure was f2.5 at 1/40th of a second. LEDs are not a constant light source and flicker on and off many times a second. While this isn’t perceptible to the naked eye, when photographed a higher shutter speeds the lights may be caught instead of on, which makes it hard to read the signs.