Limerick Junction: Photographing LED signals.

Yesterday, 13 October 2018, I exposed these views of an LED (light emitting diode) signal on Irish Rail at Limerick Junction.

Take a careful look at the yellow aspects in the respective images.

In the top photo, the yellow LEDs appear relatively dim (and much dimmer than they seemed in person). On the bottom photo these are brighter.

Exposed at 1/400th of a second.
1/60th of a second.

Many LEDs do not produce constant light output and flicker many times a second. Although you cannot see this with your naked eye and the light output appears constant, in fact the light is blinking. When you use a fast shutter speed the camera only captures a portion of the light emitted and so the signal lights seem too dim.

The key when photographing LED signals is to use a relatively low shutter speed. In this case 1/60thof second is much better than 1/400th.

Another tip when making effective LED signal photos is to make the most of subdued lighting which can make the signals seem brighter than the light around them.

 

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