Danella Photographic

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High intensity discharge lighting (halcyon) is found in most indoor and some outdoor sports arenas. These venues often include high school and college basketball courts and hockey rinks.

The following information was passed to us by local ( Upstate NY ) commercial photographer David Tewksbury. The research can be credited to Guy Rhodes.

Discharge lights cycle at 60Hz (in the US) and as you can see in these images http://www.sportsshooter.com/guyrhodes/wbtests/
They vary in both intensity and color balance.

The third frame on this site shows very dramatically the shift in both brightness and color balance through the cycle. This is why with fast shutter speeds under these lights you get such a variation of exposure and color balance, and why people strobe arenas.

The same person who did these tests has put together an animated GIF that shows the cycling in a gym. Pretty dramatic changes.

http://www.guyrhodes.com/photo/flicker_lapse.gif

Here is the explanation associated with the animated GIF

The burst was shot @ 8fps, ISO 1600, 1/2000th @ 2.8. I had the camera in auto white balance mode. Lining these frames up next to each other (twelve total in the animation) allows us to see the problematic pulsing these lights produce.

I’ll remind everyone that this flickering, including in the gym where this was shot, is TOTALLY invisible to the naked eye.

Notice the exposure and color variations across every surface of the gym as lights flicker at different times (wired to different phases of the building’s power).

This is why shooting under these lights at fast shutter speeds is hit-or-miss. Sometimes you’ll catch the lights as they peak, other times, you’ll catch the bottom of the wave as the brightness / color are at their worst.

If you’re lucky, the electricians have spread the different phases of power across the entire group of lights, rather than wiring large neighboring areas of lights on the same phase. At E.C. Central’s gym (where the time lapse was shot), we’ve lucked out. You’ll notice lights seem to be wired to different phases every third fixture. This means that by the time the light reaches floor level, the pulsing becomes very manageable, and the light stays somewhat even.

I’ve been to football stadiums, however, where entire poles of lights are on the same phase (meaning they all flicker at the same time), leaving entire percentages of the field in near darkness at the “bottom” of the flicker when shot in a burst, depending on how the lights are focused.

So if you are shooting under discharge lighting and need a shutter speed faster than 1/60th be aware that variations in exposure and color balance will occur.

This entry was posted on Tuesday, January 9th, 2007 at 5:25 pm and is filed under Shooting Problems. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.